TECHNICAL FIELD

The present invention relates to a foldable bicycle frame, and in particular but not exclusively to a foldable bicycle frame having improved rigidity and resistance to flexion.

BACKGROUND

Bicycles experience twisting forces during cornering and during alternate left-right force loading of the pedalling cycle.

However, if the structure of the bicycle is not of sufficient rigidity, the inability to resist riding forces results in flexion preventing the wheels from tracking in the same plane or preventing rider contact points (for example, the pedals, handlebars and saddle) moving relative to one another (either longitudinally along a length of the bicycle, or laterally). That flexion undermines confidence in the cornering, pedalling, accelerating and braking stability of the bicycle, making the ride unpredictable.

Conventional folding bicycles are especially poor at resisting twisting flexion due to the presence of hinges within the bicycle frame which facilitate folding. When a conventional folding bicycle hinge is under load, the flexion can result in one face of the hinge sliding against the other.

The present invention has been devised with the foregoing in mind.

SUMMARY OF INVENTION

According to a first aspect, there is provided a foldable bicycle frame. The foldable bicycle frame may comprise a plurality of frame portions pivotably connected to one another such that the frame is operable between a folded configuration and unfolded configuration. At least one of the frame portions may comprise a monocoque construction.

A monocoque or “structural skin” construction is one in which loads are primarily supported by a structure’s external shell or skin rather than by a frame of tubes, beams or rods. A foldable bicycle frame having one or more frame portions comprising a monocoque constmction may provide a stiff, lightweight structure having a greater rigidity than a conventional foldable bicycle frame comprising a plurality of tubes or beams connected (e.g., welded) to one another. Use of a ‘structural skin’ or external shell allows material to be provided where structurally required, and removed or not included where not structurally required, as the structure or design of the frame portions is not limited by simply adding or removing tubes, beams or rods. That may increase rigidity (for example, in one or more of compression, extension and torsion), reduce weight and improve portability of the foldable bicycle frame.

A greater rigidity may enable the foldable bicycle frame to better resist flexion (for example, both torsion acting to cause twisting of the bicycle frame, and compression or tension acting to elongate or compress the bicycle frame) during operation than a conventional foldable bicycle frame, which may improve ride stability. In particular, the increased rigidity of the bicycle frame may enable greater dimensional stability of rider contact points (such as the pedals, handlebars and saddle) and a more consistent spatial arrangement of the rider contact points relative to one another in use.

The frame may comprise a front frame portion and a rear frame portion each pivotably connected to a mid frame portion.

At least one of the front frame portion, mid frame portion and rear frame portion may comprise a monocoque construction.

One or more of the frame portions may comprise or be formed, at least in part, from a composite material. That may further reduce a weight of the foldable bicycle frame whilst ensuring a stiff structure with sufficient rigidity. The composite material may be or comprise a carbon fibre composite material. Alternatively, the composite material may or comprise a natural fibre composite material, for example a flax composite material.

The monocoque construction of the at least one frame portion may comprise an internal support. That may improve resistance of the monocoque construction to buckling whilst reducing weight compared to a solid structure. The internal support may comprise a foam material, for example polyurethane foam.

The mid frame portion may comprise a first end and a second end. A plurality of elongate sections may extend, for example substantially longitudinally, between the first end and the second end of the mid frame portion. That arrangement may provide material only where required over the cross-section of the mid frame portion. That may also enable a cross-sectional area of the mid frame portion to be maximized, increasing the second moment of area and therefore increasing rigidity (in compression, extension, and torsion) of the mid frame portion, whilst simultaneously reducing an amount of material used in order to reduce weight.

The plurality of elongate sections may comprise a first elongate section and at least two second elongate sections. The at least two second elongate sections may be positioned below the first elongate section in use. The second elongate sections may be arranged symmetrically with respect to the first elongate section.

The second elongate sections may be arranged or configured to sleeve a rear wheel connected to the rear frame portion when the foldable bicycle frame is in the folded configuration. That may enable the cross-sectional area of the mid frame portion to be maximized around the rear wheel to increase rigidity, whilst also reducing or minimizing a size of the foldable bicycle frame in the folded configuration.

According to a second aspect, there is provided a foldable bicycle frame. The foldable bicycle frame may comprise a plurality of frame portions pivotably connected to one another such that the frame is operable between a folded configuration and an unfolded configuration. A rear frame portion of the frame may comprise first and second lateral sections configured to attach to respective first and second lateral sides of a rear wheel. The rear frame portion may also comprise an intermediate or connecting section extending between the first and second lateral sections. The first and second lateral sections and the intermediate section may form a unitary structure. The first and second lateral sections may be integrally formed with the intermediate section.

A rear frame portion including an intermediate section extending between and integrally formed with the lateral sections attached to a rear wheel may provide the rear frame portion with greater structural rigidity compared to a conventional rear frame having separate, disconnected lateral sections attached to each side of the rear wheel. That structure may also simplify manufacturing and assembly by reducing the number of separate components of the foldable bicycle frame.

The intermediate section of the rear frame portion may be configured, shaped or arranged to act as a mudguard in the unfolded configuration. The intermediate section may be configured to cover an upper part of a rear wheel attached to the rear frame portion in the unfolded configuration. That may prevent dirt and liquid from a rear wheel from being distributed forwards and/or upwards during riding without requiring a separate mudguard structure to be fastened to the foldable bicycle frame. The intermediate section also contributes to the structural rigidity of the rear frame portion. As such, employing the intermediate section as an integral mudguard may reduce weight and improve the mechanical performance of the foldable bicycle frame, whilst also keeping a rider clean and dry during use. An integral mudguard may also improve simplicity of assembly and maintenance of the foldable bicycle frame.

The intermediate section may comprise a substantially planar structure. The intermediate section may comprise a substantially flat upper surface. That may enable luggage or other objects to be conveniently supported or carried on the bicycle during riding, whilst also protecting the luggage or other objects from liquid and dirt. The luggage or other items may also be stably and securely supported due to the improved structural rigidity of the rear frame portion provided by the intermediate section.

The rear frame portion may comprise at least one trolley wheel configured to contact the ground in the folded configuration. That may provide improved stability when supporting the foldable bicycle frame on the trolley wheels in the folded configuration, by utilising the improved structural rigidity provided by a unitary rear frame portion. The trolley wheels may be disposed on the intermediate section.

The rear frame portion may comprise or be formed from a composite material. That may further reduce a weight of the foldable bicycle frame whilst ensuring a stiff structure with sufficient structural rigidity. The composite material may be or comprise a carbon fibre composite material. Alternatively, the composite material may or comprise a natural fibre composite material, for example a flax composite material.

According to a third aspect, there is provided a foldable bicycle frame. The foldable bicycle frame may comprise a plurality of frame portions pivotably connected to one another such that the frame is operable between a folded configuration and an unfolded configuration. The foldable bicycle frame may comprise a hinge connecting two of the pivotably connected frame portions. The hinge may comprise a first hinge portion on one of the frame portions. The first hinge portion may comprise a first mating surface. The hinge may also comprise a second hinge portion on another of the frame portions. The second hinge portion may comprise a second mating surface configured to contact the first mating surface in the unfolded configuration. The first and second mating surfaces may comprise complementary engagement features.

The complementary engagement features may be configured to improve torsional rigidity of the hinge between adjacent frame portions during riding compared to a conventional hinge structure (e.g., with substantially flat or planar mating surfaces), by inhibiting or preventing rotation of the first and second hinge portions relative to one another. That may enable the foldable bicycle frame to better resist torsional flexion during riding, which may improve ride stability. The complementary engagement features may also act to easily and accurately locate the first and second hinge portions in the correct position when placing the foldable bicycle frame in the unfolded configuration. The complementary engagement features may improve the mechanical performance of the foldable bicycle frame without affecting an aesthetic look of the foldable bicycle frame, with the complementary engagement features hidden in the unfolded configuration.

Each mating surface may comprise at least one engagement feature. Each mating surface may comprise a plurality of engagement features. Each mating surface may comprise four engagement features. The four engagement features may be arranged substantially in a cross shape.

One of the first mating surface and the second mating surface may comprise at least one protrusion, and optionally a plurality of protrusions. The other of the first mating surface and the second mating surface may comprise a complementary recess, optionally a plurality of complementary recesses, each configured to receive a protrusion.

The complementary engagement features may be disposed at or adjacent a perimeter of the first and second mating surfaces. That may maximize torsional rigidity by positioning the engagement features further from a pivot of the hinge, maximizing the increase in torsional rigidity without affecting an aesthetic look of the foldable bicycle frame.

At least one of the mating surfaces may comprise a resilient material. The resilient material may be or comprise a rubber material. That may reduce a magnitude of forces experienced by the foldable bicycle frame if the hinge is closed quickly or forcefully (e.g., slammed), by absorbing impact energy. That may be particularly beneficial for a foldable bicycle frame comprising a composite material, which can suffer delamination when subjected to impact forces. Delamination can propagate through further use and may eventually lead to failure. Reducing impact forces using a resilient material on at least one of the mating surfaces may improve longevity of the foldable bicycle frame.

A surface of the resilient material may be proud of the remainder of the mating surface when the foldable bicycle frame is not in the unfolded configuration, for example when the hinge is open and the mating surfaces are not in contact. That may ensure the resilient material contacts the other mating surface first when closing the hinge. The resilient material may be configured to compress upon placing the foldable bicycle frame in the unfolded configuration, for example by closing the hinge.

According to a fourth aspect, there is provided a foldable bicycle frame. The foldable bicycle frame may comprise a plurality of frame portions pivotably connected to one another such that the frame is operable between a folded configuration and an unfolded configuration. The foldable bicycle frame may also comprise at least one trolley wheel configured to contact the ground in the folded configuration. The trolley wheel may be angled relative to a vertical direction of the bicycle in use.

In the folded configuration, a bottom of the trolley wheel may be further outboard than a top of the trolley wheel. In the unfolded configuration, a top of the trolley wheel may be further outboard than a bottom of the trolley wheel.

Typically, trolley wheels on conventional foldable bicycle frames are substantially upright or parallel with a vertical direction in use (for example, a direction substantially perpendicular to a surface or ground on which the bicycle is ridden, or a direction substantially parallel to a radial axis of a rear wheel of the bicycle). Trolley wheels which are spaced wider apart improves the stability of the foldable bicycle frame in a folded configuration. However, wider spacing of conventional upright trolley wheels brings the trolley wheels closer to a rider’s feet (e.g., heels) during pedalling. That may result in a rider’s feet contacting or hitting the trolley wheels during pedalling, increasing both difficulty of operation and risk of injury.

By providing an angled trolley wheel (for example, angled relative to a vertical direction in use), a lower part of the trolley wheel may be further outboard than an upper part of the trolley wheel when in the folded configuration. That may effectively provide a wider spacing of the trolley wheels at the contact point with the ground in the folded configuration, improving stability. However, the angle of the trolley wheels also enables a lower part of the trolley wheel allows a lower part of the trolley wheel to be further inboard than an upper part of the trolley wheel when in the unfolded configuration. That may increase the space available for a rider’s feet during pedalling and reduce a risk of the rider’s feet, improving safety and ease of operation.

At least one trolley wheel may be disposed on a rear frame portion of the frame.

The foldable bicycle frame may comprise a pair of angled trolley wheels. The trolley wheels may be arranged at equal but opposite angles to one another, such that the trolley wheels are angled substantially symmetrically with respect to the vertical direction. The trolley wheels may alternatively be arranged at different angles to one another, such that the trolley wheels are angled asymmetrically with respect to the vertical direction. The trolley wheels may be disposed on opposing sides of the frame.

The at least one trolley wheel may be angled between substantially 0.5° and substantially 89.5°, or between substantially 1° and substantially 89°, or between substantially 2° and substantially 88°, or between substantially 5° and substantially 85°. The trolley wheel may be angled between substantially 0.5° and substantially 45°, or between substantially 5° and substantially 40°, or between substantially 10° and substantially 35°, or between substantially 15° and substantially 30°. The trolley wheel may be angled between substantially 20° and substantially 25°, and may be angled at substantially 23°.

According to a fifth aspect, there is provided a foldable bicycle frame. The foldable bicycle frame may comprise a plurality of frame portions pivotably connected to one another such that the frame is operable between a folded configuration and an unfolded configuration. The foldable bicycle frame may comprise features from the foldable bicycle frames of two or more of the first, second, third and fourth aspects described above. According to a sixth aspect, there is provided a foldable bicycle steering column. The foldable bicycle steering column may comprise a foldable stem. The foldable stem may be configured to support handlebars and operable between a folded configuration and an unfolded configuration. The stem may comprise a retaining element. The retaining element may be configured to releasably secure the stem in the folded configuration. The retaining element may be disposed internally within the stem in the unfolded configuration.

Typically mechanisms for securing a foldable stem in the folded and/or unfolded configurations are located externally on the stem. A retaining element that is configured to secure the stem in the folded configuration but disposed internally within the stem in the unfolded configuration avoids or reduces the number of external protrusions from the stem, particularly when the stem is in the unfolded configuration. That may improve ease of use and safety for a user by reducing a risk of items becoming snagged on protrusions from the stem. That may also increase rigidity of the stem by providing a stiffening effect in the unfolded configuration, due to additional material in the cross-section of the stem.

The foldable bicycle steering column may comprise a locking collar. The locking collar may be configured to be placed around a fork steerer tube to apply a preload to a bearing disposed adjacent a head tube. The locking collar may comprise a releasable locking mechanism to lock the locking collar in place on the fork steerer tube.

A conventional threaded headset typically requires both a threaded top race configured to be disposed on a fork steerer tube to apply a preload to a bearing adjacent a top part of a head tube, and a locking nut configured to hold the threaded top race in position on the fork steerer tube. A conventional threadless headset arrangement typically requires a significant length of the fork steerer tube to extend from the head tube for a stem to sit over the fork steerer tube. The locking collar may enable a stack height (a height or length by which a steerer tube extends from a head tube, for example above a head tube) to be reduced. A reduced stack height may provide additional space within an internal space of the stem, allowing for the retaining element to be disposed within the stem in the unfolded configuration. A reduced stack height may also increase an aerodynamic advantage of a user by lowering a torso angle of the user while riding. That may be particularly useful for racing purposes (such as on time trial bicycles).

The locking collar may also incorporate the dual functions of applying a preload to a bearing adjacent a head tube and locking in place on the fork steerer tube to ensure the correct preload is applied. Avoiding the need for a separate locking nut may also enable a more precise preload to be applied, for example, compared to a conventional threaded headset, where tightening of the locking nut inevitably causes rotation of the threaded top race as the locking nut and threaded top race contact one another, altering the preload applied by the threaded top race.

The locking collar may comprise an open or partial annulus having a first end and a second end. The locking mechanism may be configured to vary a distance between the first end and the second end to lock the locking collar in place on the fork steerer tube. The locking mechanism may be or comprise a pinch bolt.

That may allow the locking collar to be easily compressed or expanded to be locked in place on or unlocked from the fork steerer tube. The locking collar may comprise an internal threaded portion configured to engage with an external threaded portion of the fork steerer tube.

That may allow a bearing preload applied by the locking collar to be easily controlled or adjusted prior to the locking collar being locked in place.

A wall of the lower end of the stem may be joggled to provide the stem with a narrower portion and a wider portion substantially adjacent one another. The retaining element may be disposed internally within the wider portion of the stem in the unfolded configuration. The joggle may be or comprise or form a substantial discontinuity in width or diameter of the stem, for example such that a platform or shoulder is formed in the wall of the stem. The narrower portion of the stem may be narrow enough to be received within a fork steerer tube. The wider portion of the stem may be wide enough to be unable to be received within the fork steerer tube. The joggled wall may allow the narrower portion of the stem to be received within the fork steerer tube to allow the stem to be secured to the fork steerer tube, whilst the wider portion provides increased internal space within the stem to accommodate the retaining element in the unfolded configuration. The increased diameter of the wider portion may provide additional structural stiffness and stability to the stem and inhibit or prevent flexion or twisting of the stem (for example, relative to the fork steerer tube or the head tube). That may enable greater dimensional stability of rider contact points (such as the pedals, handlebars and saddle) and a more consistent spatial arrangement of the rider contact points relative to one another in use.

The wider portion of the stem may also provide a platform or shoulder configured to be disposed on or contact one or more components of a headset above a head tube in use. That may provide additional stiffness and resistance to flexion or rotation of the stem (for example, relative to the fork steerer tube or the head tube).

The foldable stem may comprise an actuator configured to releasably secure the stem in the unfolded configuration. At least a portion of the actuator may be configured to engage with the retaining element to secure the stem in the folded configuration.

That may avoid two distinct or separate systems for securing the foldable stem in both the folded and unfolded configurations. That may reduce or minimise a number of components required to releasably secure the stem in both the folded and unfolded configurations, which may improve ease of use and manufacturing.

The stem may comprise a first portion pivotably connected to a second portion. The actuator may comprise an eccentric cam lever pivotably connected to the first portion of the stem. The actuator may further comprise an elongate portion comprising a first end and a second end. The first end of the elongate portion may be pivotably connected to the eccentric cam lever. The second end of the elongate portion may be pivotably connected to the second portion of the stem. The elongate portion may be configured to engage with the retaining element to secure the stem in the folded configuration. That may provide a simple mechanical system enabling both easy folding and unfolding of the stem, and also convenient provision of a component to engage with or be received by the retaining element when the stem is in the folded configuration.

The elongate portion may be disposed, positioned or located between the stem and the eccentric cam lever in the unfolded configuration.

That may minimise a number of external components on the stem which are exposed in the unfolded configuration.

The retaining element may be or comprise a resiliently deformable material. The retaining element may be or comprise a sprung catch. The sprung catch may be or comprise any suitable material, for example a plastic material, a polymeric material such as an elastomeric material or a rubber material, a metal, an alloy etc.

The stem may comprise an integral portion configured to be received within a fork steerer tube to secure the stem to the fork steerer tube.

The integral portion may be configured to be uniformly expandable to secure the stem to the fork steerer tube.

Conventional folding bicycle stems typically use a quill wedge received within a fork steerer tube to secure the stem to the fork steerer tube. A quill wedge expands non-uniformly and effectively secures at a single point or across a single line of action, creating a pivot point. Because a clearance is also required to initially insert the quill wedge into the fork steerer tube, the pivot point is accompanied by a space at an open end of the fork steerer tube. That is problematic for folding bicycle stems which are typically much longer than non-folding bicycle stem, which increases a moment at the handlebars, increasing play and decreasing stability. Using a uniformly expanding portion may prevent the formation of a pivot point and increase stability for a user.

The integral portion may comprise a pair of opposing wedges disposed along a longitudinal axis. Each wedge may have an angled surface. The integral portion may also comprise at least one plate in contact with the angled surface of both of the wedges. The wedges may be movable relative to one another along the longitudinal axis to move the at least one plate in a radial direction.

According to a seventh aspect, there is provided a locking collar for a bicycle steering column. The locking collar may be the locking collar described with respect to the sixth aspect. The locking collar may be configured to be placed around a fork steerer tube to apply a preload to a bearing disposed adjacent a head tube. The locking collar may comprise a releasable locking mechanism to lock the locking collar in place on the fork steerer tube.

The locking collar may have the same or similar features and advantages to those described with respect to the sixth aspect. The locking collar may comprise one or more recessed or notched portions to allow the locking collar to flex to lock in place around the fork steerer tube. The one or more recessed or notched portions may be located on an inner circumferential surface of the locking collar.

The locking collar may comprise one or more portions configured to allow rotational force to be manually applied to the locking collar. The one or more portions may comprise one or more protrusions and/or one or more recesses.

According to an eighth aspect, there is provided a foldable bicycle stem. The stem may be configured to support handlebars and operable between a folded configuration and an unfolded configuration. The stem may comprise an integral portion configured to be received within a fork steerer tube to secure the stem to the fork steerer tube. The integral portion may be configured to be uniformly expandable to secure the stem to the fork steerer tube.

The foldable stem and the integral portion may have the same or similar features and advantages to those described with respect to the sixth aspect.

According to a ninth aspect, there is provided a foldable bicycle comprising the foldable bicycle frame of any of the first, second, third, fourth or fifth aspects described above.

Features which are described in the context of separate aspects and embodiments of the invention may be used together and/or be interchangeable wherever possible. Similarly, where features are described in the context of a single embodiment for brevity, those features may also be provided separately or in any suitable sub-combination. Features described in connection with the foldable bicycle frame of the first aspect may have corresponding features definable with respect to the foldable bicycle frame of any of the second, third and fourth aspects, and vice versa, and these embodiments are specifically envisaged.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 A shows an embodiment of a foldable bicycle frame in an unfolded configuration, in accordance with the invention;

FIG. IB shows the foldable bicycle frame shown in FIG. 1 in a folded configuration;

FIG. 1C shows a cross-sectional view of a monocoque construction in accordance with an embodiment of the invention;

FIG. 2 shows a mid frame portion of the foldable bicycle frame shown in FIG. 1 comprising a plurality of elongate sections, in accordance with an embodiment of the invention; FIG. 3 shows a front hinge of the foldable bicycle frame shown in FIG. 1 comprising complementary engagement features to increase torsional rigidity, in accordance with an embodiment of the invention;

FIG. 4 shows a rear frame portion of the foldable bicycle frame shown in FIG. 1 comprising a unitary structure comprising opposing lateral sections and an intermediate section, in accordance with an embodiment of the invention;

FIGs. 5 and 6 respectively show rear and top views of trolley wheels of the foldable bicycle frame shown in FIG. 1 angled relative to a vertical direction of the bicycle, in accordance with an embodiment of the invention;

FIGs. 7A to 7C show a foldable bicycle steering column in accordance with an embodiment of the invention;

FIGs. 8A and 8B show a cross-section of the foldable bicycle steering column shown in FIGs. 7A to 7C;

FIG. 8C shows a locking collar shown in FIG. 8B in greater detail.

Like reference numerals in different Figures may represent like elements.

DETAILED DESCRIPTION

Figures 1 A and IB show an embodiment of foldable bicycle 1 comprising a foldable bicycle frame 10 in an unfolded configuration (shown in Figure 1 A) and a folded configuration (shown in Figure IB), in accordance with the present invention. The frame 10 comprises a plurality of frame portions pivotably connected to one another such that the frame is operable between the unfolded configuration and the folded configuration.

In the embodiment shown, the frame 10 comprises a front frame portion 10 A, a mid frame portion 10B and a rear frame portion 10C. The front frame portion 10A and the rear frame portion 10C are each pivotably connected to the mid frame portion 10B. The front frame portion 10 A is connected to the mid frame portion 10B by a front hinge 12. The rear frame portion 10C is connected to the mid frame portion 10B by a rear hinge 14. However, it will be appreciated the foldable bicycle frame 10 may comprise any suitable number of frame portions pivotably connected to one another.

The front frame portion 10A comprises a through-aperture configured to receive a steerer tube 16. The steerer tube 16 is rotatable within the through-aperture. The steerer tube 16 connects handlebars 18 to front forks 20 attached to a front wheel 22, enabling a rider to steer the bicycle 1 (for example, when riding). The mid frame portion 10B comprises an aperture or recess configured to receive a seat post 24 connecting a seat 26 to the frame 10. A pair of crank arms 28 and at least one chain ring 30 are mounted on the mid frame portion 10B. A pedal 32 is attached to an end of each crank arm 28, enabling reciprocating motion of a rider’s legs to drive a chain 34 via the crank arms 28 and chain ring 30, which in turn drives rotational motion of a rear wheel 36. The rear wheel 26 is connected to the rear frame portion 10C. At least one trolley wheel 36 is mounted on the rear frame portion 10C. The front frame portion 10A and the mid frame portion 10B each comprise a monocoque or “single shell” construction. Loads experienced by the front frame portion 10A and the mid frame portion 10B are therefore primarily carried or supported by a substantially continuous external skin, shell or membrane of the front frame portion 10A and the mid frame portion 10B respectively, rather than by a frame of connected beams or tubes. Alternatively, only one of the front frame portion 10 A and the mid frame portion 10B may comprise a monocoque construction. It will be appreciated the rear frame portion 10C may comprise a monocoque construction. It will also be appreciated that although one or more of the frame portions 10A, 10B, 10C comprise a monocoque construction, the one or more frame portion 10A, 10B, 10C may each further comprise one or more other components fixedly connected to the monocoque construction in order to support mechanical interfaces, for example including but not limited to hinges, bearings etc. (discussed further below).

In the embodiment shown, the front frame portion 10A and the mid frame portion 10B each comprise an external skin or shell 38. The skin 38 defines a substantially hollow space in which an internal support 40 is disposed, depicted in the cross-sectional view shown in Figure 1C (which is not representative of the specific cross-sectional shape of either the front frame portion 10A or the mid frame portion 10B). The skin or shell 38 comprises a carbon fibre composite material, although it will be appreciated other materials may alternatively be used, for example a natural fibre composite material such as a flax composite material, or a sheet metal or alloy material such as steel or aluminium (or an aluminium alloy). The internal support 40 comprises a foam material such as polyurethane foam, although it will be appreciated other materials and/or structures may alternatively be used, for example a honeycomb material or structural ribs.

Alternatively, the front frame portion 10A and/or the mid frame portion 10B may not comprise an internal support in the hollow space defined by the external skin 38. The external skin 38 of the front frame portion 10A and/or the mid frame portion 10B may also not define a hollow space in which an internal support can be disposed. The monocoque construction of the front frame portion 10A and/or the mid frame portion 10B may alternatively be or comprise a substantially continuous membrane of material.

The carbon fibre composite external skin 38 of the frame portions comprising a monocoque construction may be formed by impregnating one or more layers of carbon fibre material with a resin and curing the impregnated carbon fibre material in a desired shape (for example, using a tool or mould). The carbon fibre material may be cured over an internal support having the desired shape (for example, a foam structure cut or moulded to shape to form an undercut of the final surface). The carbon fibre may be pre-impregnated with resin (known as “pre-preg” material), or may be impregnated with resin during the manufacturing process, for example via resin infusion.

The mid frame portion 10B comprises a plurality of elongate sections 42 extending substantially longitudinally between a first end (for example, rearward end) and a second end (for example, forward end) of the mid frame portion 10B. That arrangement may provide material only where required over the cross-section of the mid frame portion. That may enable a cross-sectional area of the mid frame portion to be maximized, increasing the second moment of area and therefore increasing rigidity (in one or more of compression, extension and torsion) of the mid frame portion, whilst simultaneously reducing an amount of material used in order to reduce weight. The plurality of elongate sections 42 blend or merge into one larger or blended closed section at each of the first end and the second end of the mid frame portion 10B, forming a continuous structure in the mid frame portion 10B. The mid frame portion 10B therefore transitions from a single larger closed section at an end of the mid frame portion 10B to a plurality of independent closed sections 42 and back to a single larger closed section at an opposing end of the mid frame portion 10B. The larger or blended closed sections provide additional rigidity and stiffness at each end of the mid frame portion 10B. By merging and anchoring the respective ends of each of the elongate sections 42 to a single larger section having increased rigidity and stiffness, the structural benefits provided by the elongate sections 42 may be maximised. The overall structure of the mid frame portion 10B comprising a plurality of elongate sections 42 which transition into a single larger section at respective ends of the mid frame portion 10B may increase a rigidity and stiffness of the mid frame portion 10B and the frame 10 as a whole, providing increased resistance to flexion in each of torsion (acting to twist the frame 10), extension and compression (acting along a longitudinal axis of the bike, from front to back or in a fore-aft direction).

In the embodiment shown, the plurality of elongate sections 42 comprises a first elongate section 42a. The first elongate section 42a forms or comprises an upper part of the mid frame portion 10B in use. The first elongate section 42a spans substantially a full width of the mid frame portion 10B, although that is not essential. The plurality of elongate sections 42 also comprises two second elongate sections 42b. The second elongate sections 42b are positioned below the first elongate section 42a and form or comprise a lower part of the mid frame portion 10B in use. In the embodiment shown, the mid frame portion 10B comprises two second elongate sections 42b, although any suitable number of elongate sections 42b may alternatively be used. The two second elongate sections 42b are spaced apart from one another with respect to a central longitudinal axis of the frame 10. The two second elongate sections 42b are disposed on opposing lateral sides of the mid frame portion 10B and arranged symmetrically with respect to the first elongate section 42a, although that is not essential, and the second elongate sections 42b may alternatively be arranged asymmetrically with respect to the first elongate section 42a. An aperture or cutaway is provided in each side of the mid frame portion 10B between the first elongate section 42a and the respective second elongate sections 42b. In the embodiment shown, the two second elongate sections 42b are configured to sleeve the rear wheel 36 when the bicycle 1 is in the folded configuration (as shown in Figure IB) such that the respective second elongate sections 42b are disposed on opposing lateral sides of the rear wheel 36, although that is not essential. The first and second elongate sections 42a, 42b define a space in which the rear wheel 36 is configured to be received in the folded configuration. That may enable the cross-sectional area of the mid frame portion 10B to be maximized around the rear wheel 36 to increase rigidity, whilst also reducing or minimizing a size of the foldable bicycle frame 10 in the folded configuration.

The larger or blended sections at each end of the mid frame portion 10B, into which the elongate sections 42a, 42b merge or transition, each comprise a shaped portion on the underside configured to substantially conform to a shape of the rear wheel 36 in the folded configuration, as shown in Figures IB and 2. The shaped portions are configured to closely cover or surround both an outer circumferential surface of the rear wheel 36 and also outer lateral surfaces of the rear wheel 36. The larger sections effectively provide a webbing between lateral sides of the mid frame portion 10B which partially wraps around an outer surface of the rear wheel 36 from one lateral side of the rear wheel 36 to the other. That may allow the rear wheel 36 to be securely stored by reducing play in the folded configuration.

In the embodiment shown, the elongate sections 42 each extend substantially parallel to one another, and substantially parallel to a longitudinal axis of the frame 10. However, it will be appreciated that is not essential. For example, the first elongate section 42a may extend in a direction substantially parallel to the longitudinal axis of the frame 10 (e.g., substantially horizontally), whilst the second elongate sections 42b may extend at an angle relative to that direction, such as sloping upwards from a lower point adjacent the first or rearward end to a higher point adjacent the second or forward end of the mid frame portion 10B.

Figure 3 shows the front hinge 12 connecting the front frame portion 10A to the mid frame portion 10B in more detail. The front hinge 12 is shown in an open position in Figure 3. The front hinge 12 comprises a first hinge portion 12a disposed on the front frame portion 10A, and a second hinge portion 12b disposed on the mid frame portion 10B. In the embodiment shown, the first hinge portion 12a and the second hinge portion 12b are each metallic components fixedly connected (for example, bonded or adhered) to adjacent or connecting ends of the front frame portion 10A and the mid frame portion 10B respectively. However, that is not essential, and the first and second hinge portions 12a, 12b may alternatively be integrally formed in the monocoque construction of the front frame portion 10 A and the mid frame portion 10B, or formed as solid carbon fibre pieces, bonded on to the monocoque.

The first hinge portion 12a comprises a first mating surface 44a, and the second hinge portion 12b comprises a second mating surface 44b. The first and second mating surfaces 44a, 44b are configured to contact one another when the front hinge 12 is in a closed position (for example, when the frame 10 is in the unfolded or assembled configuration, as shown in Figure 1 A). The front hinge 12 is held in the closed position by a clamping plate 50. The clamping plate 50 is configured to provide a compressive force bringing the mating surfaces 44a, 44b into contact. An actuator 52 is provided to apply and remove the compressive force via the clamping plate. In the embodiment shown, the actuator 52 comprises a quick release cam lever. The front hinge 12 comprises a pivot 46 connecting the first and second hinge portions 12a, 12b and allowing the hinge portions 12a, 12b to rotate relative to one another between the open and closed positions. In the embodiment shown, the pivot 46 is disposed on a lateral side of the frame 10, enabling the front portion 10A to rotate laterally relative to the mid frame portion 10B about the pivot 46. However, that is not essential, and the pivot 46 may be disposed in a different position on the frame 10.

The first and second mating surfaces 44a, 44b comprise complementary engagement features. The engagement features are configured to engage with one another when the front hinge 12 is in the closed position in order to prevent or inhibit rotation of the hinge portions 12a, 12b relative to one another and increase a torsional rigidity of the frame 10 across the front hinge 12. That may enhance the improved torsional rigidity provided by the monocoque construction of the front frame portion 10A and the mid frame portion 10B, but it will be appreciated the hinge 14 may equally increase torsional rigidity in a foldable bicycle frame 10 not comprising any frame portions having a monocoque construction.

In the embodiment shown, the complementary engagement features comprise a plurality of protrusions 48b on the second mating surface 44b, and a plurality of complementary recesses 48a on the first mating surface 44a. Each protrusion 48b is configured to be received within a separate recess 48a when the mating surfaces 44a, 44b are brought into contact with one another.

In the embodiment shown, the first mating surface 44a comprises four recesses 48a and the second mating surface 44b comprises four protrusions 48b. The engagement features 48a, 48b are also disposed adjacent a perimeter of each mating surface 44a, 44b and are arranged in a substantial cross shape or formation. Each of the engagement features 48a, 48b has a substantially similar shape to one another. In the embodiment shown, each engagement feature 48a, 48b has an elongated shape, in the form of a substantially oval or rounded cuboid shape. Such an elongated shape may provide additional resistance to rotational forces, for example compared to a substantially circular protrusion. In addition, each engagement feature 48a, 48b is oriented such that a longer side of the engagement feature extends in a direction substantially normal or perpendicular to a direction of travel of that area of the respective hinge portion 12a, 12b under rotational movement. That may provide increased resistance to rotation by providing a greater surface area over which the force is applied during twisting.

However, it will be appreciated the arrangement of engagement features 48a, 48b shown in Figure 3 is not essential. Any suitable number of engagement features may be used on each mating surface 44a, 44b (for example, one, two, three, five, six etc.). The engagement features 48a, 48b need not be located adjacent a perimeter of the mating surfaces 44a, 44b and may be disposed at any suitable location on the mating surfaces 44a, 44b. The engagement features 48a, 48b may not be arranged in a cross shape and may be arranged in any suitable configuration (for example, a circular arrangement or polygonal arrangement, or an abstract arbitrary shape arrangement for example, following a perimeter of the mating surfaces 44a, 44b). The engagement features 48a, 48b need not all have the same shape as one another and may each have any suitable shape (for example, a circular shape, a polygonal shape such as triangular, cuboidal, pentagonal etc.). Each of the engagement features 48a, 48b may also have the same or a different orientation to one or more of the other engagement features 48, 48b. At least one engagement feature 48a, 48b of any suitable configuration (for example, shape, orientation and/or location) provided on the respective mating surfaces 44a, 44b may provide additional torsional rigidity to the frame 10 across the front hinge 12.

The second mating surface 44b comprises a resilient material 54. The resilient material 54 comprises rubber, although any suitable resilient material may alternatively be used. The resilient material 50 is provided as a pad or layer sitting proud of the remainder of the second mating surface 44b. That may enable the resilient material 54 to contact the first mating surface 44a first when the front hinge 12 is moved to the closed position. The resilient material 50 is also configured to compress to provide cushioning when the front hinge 12 is moved to the closed position to allow the mating surfaces 44a, 44b to substantially fully contact one another in the closed position. In the embodiment shown, the resilient material 54 is shaped to substantially cover an area of the second mating surface 44b in between or not occupied by other features of the mating surface 44b, for example the protrusions 48b. The resilient material 54 comprises a single continuous area of material, although it will be appreciated the resilient material 54 may alternatively be provided as a plurality of separate areas of material over the second mating surface 44b. The resilient material 54 may alternatively be located on the first mating surface 44a, or both the first and second mating surfaces 44a, 44b may comprise a resilient material 54. The resilient material 54 may be adhered or moulded to the first and/or second hinge portions 42a, 42b.

Although the structure shown in Figure 3 relates to the front hinge 12, it will be appreciated a similar structure (for example, complementary engagement features and/or a resilient material) may additionally or alternatively be employed in the rear hinge 14 connecting the rear frame portion 10C to the mid frame portion 10B to provide similar performance. Figure 4 shows the rear frame portion IOC in more detail. In the embodiment shown, the rear frame portion IOC comprises a first lateral section 56a, a second lateral section 56b and an intermediate or connecting section 58 extending between the first and second lateral sections 56a, 56b. The first and second lateral sections 56a, 56b and the intermediate section 58 form a unitary structure. The first and second lateral sections 56a, 56b and the intermediate section 58 are integrally formed with one another. The first lateral section 56a is configured to attach a first lateral side of the rear wheel 36, and the second lateral section 56b is configured to attach to a second, opposing lateral side of the rear wheel 36.

Each of the first and second lateral sections 56a, 56b comprises a plurality of interconnected arms. Each of the plurality of arms comprises a substantially plate-like structure (for example, a thin sheet or membrane of material). In the embodiment shown, the first and second lateral sections 56a, 56b each comprise four arms (for example forming an approximately H-shaped structure), although that is not essential. A first arm 61a, 61b is pivotally connected to the mid frame portion 10B by the rear hinge 14. A first or lower end of the first arm 61a, 61b is pivotably connected to the mid frame portion 10B.

The first arm 61, 61b is configured to be forced towards a rearmost surface of the mid frame portion 10B in the unfolded configuration. The mid frame portion 10B comprises a recess or aperture in the rearmost surface, in which a latch mechanism (not shown) is disposed or housed. The latch mechanism is configured to engage and attach to a cylinder (not shown) which is fixedly connected to the rear frame portion 10B when the foldable bicycle frame 10 is placed in the unfolded configuration. That may maintain the mid frame portion 10B and the rear frame portion 10C in a substantially fixed spatial relationship to one another in the unfolded configmation, for example maintaining a consistent gap or spacing between the mid frame portion 10B and the rear frame portion 10C in the unfolded configmation. The latch mechanism automatically engages the cylinder when the foldable bicycle frame 10 is placed in the unfolded configuration. The latch mechanism may be released from the cylinder by manual actuation, for example by pushing a lever on the latch mechanism. However, it will be appreciated that is not essential. The first arm 61a, 61b may alternatively be configured to contact or be forced against a rearward surface of the mid frame portion 10B in the unfolded configuration, with a weight of the bicycle 1 and optionally a rider acting to keep the rem hinge 14 in the closed position.

In the embodiment shown the first arm 61a, 61b is oriented substantially vertically in the unfolded configmation, although that is not essential. A second arm 62a, 62b extends rearward from the first arm 61a. In the embodiment shown, the second arm 62a, 62b extends substantially horizontally from a central region of the first arm 61a, 61b (for example, not from an end of the first arm 61a, 61b). A third arm 63a, 63b and a fourth arm 64a, 64b branch off from the second arm 62a, 62b. The third arm 63a, 63b extends from the second arm 62a, 62b and comprises a strut 66 configured to connect to the axle of the rear wheel 36. The fourth arm 64a, 64b extends from the second arm 62a, 62b and connects to the intermediate section 58. A second or upper end of the first arm 61a, 61b also connects to the intermediate section 58. In the embodiment shown, the first arm 61a, 61b, second arm 62a, 62b, fourth arm 64a, 64b and intermediate section 58 form a closed loop structure (e.g., surrounding a central aperture) disposed on either side of the rear wheel 36, improving rigidity and strength of the rear frame portion 10C whilst minimizing a weight of the rear frame portion 10C. Alternatively, each of the first and second lateral sections 56a, 56b may comprise a different structure, for example a substantially continuous sheet, plate or web of material rather than a plurality of interconnected arms 61-64a, 61-64b.

The intermediate section 58 extends laterally between the first and second lateral sections 56a, 56b across the rear wheel 36. In the embodiment shown, in the unfolded configuration the intermediate section 58 is substantially positioned over a top portion of the rear wheel 36. Together, the first and second lateral sections 56a, 56b and the intermediate section 58 define a structure of the rear frame portion IOC that at least partially surround the rear wheel 36. The unitary or integral structure of the first and second lateral sections 56a, 56b and the intermediate section 58 also provide the rear frame section IOC with improved structural rigidity compared to conventional separate lateral sections connected independently to either side of the rear wheel.

In the embodiment shown, the intermediate section 58 comprises a continuous structure, surface or area of material extending rearward from the main body 62 of the rear frame section IOC to at least the outer end of the second arms 62a, 62b (and optionally beyond). Such a continuous structure may enable the intermediate section 58 to further act as an integral mudguard, preventing or inhibiting dirt and liquid from the rear wheel 36 from being distributed forward and/or upwards during riding. That may prevent the need for a separate mudguard structure to be attached to the frame 10, reducing weight and improving simplicity of assembly and maintenance of the bicycle 1 and the frame 10. The intermediate section 58 acting as an integral mudguard may also enable the mudguard to contribute to the structural performance of the frame 10, rather than a separate mudguard component adding material and weight without providing any structural benefit. The intermediate section 58 may alternatively comprise separate struts or beams (for example, one or a plurality of struts or beams) extending laterally between the first and second lateral sections 56a, 56b, which may provide improved structural performance but may not prevent dirt and liquid from being distributed forward and/or upwards from the rear wheel 36.

The intermediate section 58 comprises a substantially flat, level upper surface above the rear wheel 36 in the unfolded configuration. That may provide an additional function to the rear frame portion 10C in addition to providing the rear frame portion 10C with improved structural performance and an internal mudguard, by enabling luggage or other objects to be stably supported or carried on the bicycle 1 during riding.

The rear frame portion 10C comprises or is formed from a carbon fibre composite material, enabling the first and second lateral sections 56a, 56b and the intermediate section 58 to be formed having a unitary structure. The unitary structure may comprise a substantially continuous membrane of carbon fibre composite material moulded into the desired shape, for example described above with respect to the monocoque construction of the front frame portion 10 A and the mid frame portion 10B. However, it will be appreciated other materials may alternatively be used, for example a natural fibre composite material such as a flax composite material, or a sheet metal material such as steel or aluminium. In the embodiment shown, the strut 66 comprises an aluminium (or aluminium alloy) plug around which the carbon fibre composite material is formed to incorporate the strut 66 into the unitary structure of the rear frame portion 10C. However, it will be appreciated the strut 66 may alternatively comprise other materials such as carbon fibre composite material, other metals or alloys (for example steel). An end of the strut 66 may also have a different structure depending on whether the bicycle 1 is an electric bicycle or an analogue/manually powered bicycle. For example, an analogue bicycle may comprise a rear wheel 36 on which a conventional gear set is mounted (as shown in Figure 4). The axle of the rear wheel 36 comprises a thru-axle, with an end of the strut 66 comprising a closed loop dropout through which the thru-axle can be inserted to secure the rear wheel 36 to the rear frame portion IOC. Alternatively, the bicycle 1 may comprise a rear wheel 36 having an electric hub comprising a motor with an integral threaded axle. An end of the stmt 66 may therefore have an open dropout (for example, a slot) into which the axle of the electric hub can be received to secure the rear wheel 36 to the rear frame portion IOC.

The rear frame portion IOC also comprises at least one trolley wheel configured to contact the ground in the folded configuration (as shown in Figure IB), although that is not essential. In the embodiment shown, the rear frame portion IOC comprises two pairs of trolley wheels 38. The trolley wheels 38 are disposed on the intermediate portion 58 of the rear frame portion IOC. The trolley wheels 38 are attached to the rear frame portion IOC via a ladder frame structure, although it will be appreciated the trolley wheels 38 may be attached directly to the rear frame portion IOC. Each pair of trolley wheels 38 is disposed at or adjacent a respective end of the intermediate section 58.

One of the pairs of trolley wheels 38 located near a forward end of the rear frame portion IOC in the unfolded configuration comprises a pair of angled trolley wheels 38. The angled trolley wheels 38 are shown in further detail in Figures 5 and 6. The trolley wheels 38 are angled such that in the unfolded configuration an upper part or top of each trolley wheel 38 is further outboard (further from a central longitudinal axis of the frame 10) than a lower part or bottom of the trolley wheel 38, and in the folded configuration a lower part or bottom of each trolley wheel 38 is further outboard than an upper part or top of the trolley wheel 38. That arrangement provides a wider spacing between the ground contact points of the two trolley wheels 38 in the folded configuration, improving stability. However, the angled nature of the trolley wheels 38 means a lower part of each trolley wheel 38 is further inboard in the unfolded configuration, increasing a clearance for a rider’s feet during pedalling compared to a conventional pair of upright or vertical trolley wheels having the same width between ground contact points. Due to different personal biomechanics including different feet positions during pedalling (for example, heel-in or heel-out), widening a spacing between upright trolley wheels may result in a rider’s feet hitting the trolley wheels during pedalling. Such contact may be prevented or inhibited by employing angled trolley wheels 38, improving safety and ease of operation.

In the embodiment shown, each of the angled trolley wheels 38 is disposed at an angle of approximately 23° relative to a vertical direction or axis of the bicycle in use (for example, a direction perpendicular to a surface or ground on which the bicycle 1 is being ridden, or a direction substantially parallel to a radial axis of the rear wheel 36). Each of the angled trolley wheels 38 may alternatively be disposed at any suitable angle relative to a vertical direction of the bicycle in use, for example between substantially 0.5° and substantially 89.5°. The trolley wheels 38 are disposed on opposing sides of the frame 10 and arranged at equal but opposite angles to one another, for example angled away from the vertical direction in opposing lateral directions relative to the frame 10, although that is not essential. For example, the trolley wheels 38 may be angled at different angles due to rider biomechanics such as a different foot position between a rider’s left and right side (for example, different degrees of heel-in or heel-out during pedalling). Each trolley wheel may have a diameter of between substantially 5mm and substantially 100mm, although trolley wheels having any suitable diameter may be used.

In the embodiment shown, only one pair of trolley wheels 38 comprises a pair of angled trolley wheels, although it will be appreciated the frame 10 may comprise two or more pairs of trolley wheels 38. Alternatively, the frame 10 may comprise no angled trolley wheels, and may comprise conventional upright or vertical trolley wheels. Any suitable number of trolley wheels 36 may be employed (for example, one, two, three, four, five or more etc.), and the trolley wheels 36 may be located at any suitable position or on any suitable part on the rear frame portion IOC. Alternatively, the frame 10 may not comprise trolley wheels.

Figures 7A and 7B show an embodiment of a steering column 100 for a foldable bicycle, in a folded configuration (Figure 7A) and an unfolded configuration (Figure 7B), in accordance with the present invention. The steering column 100 may be used with the foldable bicycle frame 10 described above with respect to Figures 1 to 6. The steering column 100 comprises a foldable stem 102 configured to support handlebars 104. In the embodiment shown, the foldable stem 102 comprises a first portion 102a and a second portion 102b pivotably connected to one another. The steering column 100 also comprises a front fork 106 having a fork steerer tube 108. The foldable stem 102 is configured to be secured to the fork steerer tube 108 to enable a user to steer a bicycle using the handlebars 104. In the embodiment shown, the foldable stem 102 comprises an integral portion 110 configured to be received within the fork steerer tube 108 to secure the stem 102 to the fork steerer tube 108. However, that is not essential, and the stem 102 may alternatively be secured to the front fork 106 in any suitable manner.

The foldable stem 102 comprises a retaining element 112. The retaining element 112 is configured to releasably secure the stem 102 in the folded configuration, to prevent the handlebars 104 from inadvertently moving around while in the folded configuration. The foldable stem 102 also comprises an actuator 114 configured to releasably secure the stem 102 in the unfolded configuration. In the embodiment shown, at least a portion of the actuator is configured to engage with the retaining element 112 to secure the stem 102 in the folded configuration, although that is not essential.

Figure 7C shows an enlarged portion of Figure 7A with the stem 102 in the folded configuration and showing the actuator 114 in greater detail. In the embodiment shown, the actuator 114 comprises an eccentric cam lever 114a. The cam lever 114a is pivotably connected to the first portion 102a of the stem 102. The actuator 114 also comprises an elongate portion 114b (for example, a rod, tube or stmt) having a first end and second end. The first end of the elongate portion 114b is pivotably connected to the cam lever 114a. The second end of the elongate portion 114b is pivotably connected to the second portion 102b of the stem 102. In the embodiment shown, when the stem 102 is in the folded configuration, the elongate portion 114b engages with and is received by the retaining element 112, as shown in Figure 7C. That enables the stem 102 to be releasably secured in the folded configuration. In the embodiment shown, the retaining element 112 comprises a sprung catch (for example, made from a resiliently deformable or elastic material) configured to receive the elongate portion 114b via a snap fit, although that is not essential. The spmng catch may comprise or be formed from any suitable material to form a resiliently deformable structure, for example a plastic or polymeric material, a metal or alloy etc.

However, the retaining element 112 may alternatively be configured to secure the stem 102 in the folded configuration without engaging with or interacting with the actuator 114 or any another component of the stem 102. For example, the retaining element 112 may comprise separate portions respectively located on the first portion 102a and the second portion 102b of the stem 102. The portions of the retaining element 112 may be configured to interact and/or engage to releasably secure the stem 102 in the folded configuration, and may each be disposed internally within the stem 102 in the unfolded configuration When the stem 102 is placed in the unfolded configuration, the cam lever 114a may be pivoted or rotated towards a closed position (as shown in Figure 7B) to secure the stem 102 in the unfolded configuration. Upon rotation of the cam lever 114a where it is pivotably connected to the first portion 102a of the stem 102, the elongate portion 114b also pivots where it is pivotably connected to the cam lever 114a and where it is pivotably connected to the second portion 102b of the stem. The elongate portion 114b is placed under tension when the cam lever 114a is moved substantially towards the closed position, pulling the first portion 102a and the second portion 102b of the stem 102 together to secure the stem in the folded configuration. The tension may be at a maximum when the various pivot points are substantially aligned with one another. The cam lever 114a may then be rotated further towards the closed position such that the tension in the elongate portion 114b is reduced slightly. The actuator 114 therefore acts to keep the stem 102 in the unfolded configuration unless the cam lever 114a is manually rotated past the point of maximal tension to an open 19econdl9nn. As the elongate portion 114b moves slightly away from the fully closed position during normal use in the unfolded position, the increase in tension in the elongate portion acts to force the actuator back towards the closed position. It will be appreciated the same operation may be achieved with the cam lever 114a pivotably connected to the second portion 102b, and the elongate portion 114b pivotably connected to the first portion 102a instead. In the unfolded configuration, the elongate portion 114b of the actuator 114 is disposed between the stem 102 and the cam lever 114a. That may shield the elongate portion 114b and reduce a number of external components on the stem 102 which are exposed, which may improve ease of use and user safety. However, it will be appreciated the stem 102 may comprise any suitable mechanism or means to secure the stem 102 in the unfolded configuration.

Figure 8A shows a side view of the steering column 100 with an axis A. Figure 8B shows a cross-sectional view through the steering column 100 along the axis A.

As shown in Figure 8B, the fork steerer tube 108 passes through a head tube 116 of the bicycle frame. The head tube 116 may be or correspond to the through-aperture in the front frame portion 10A described above with respect to Figure 1, although that is not essential. A bearing 120 is disposed between the fork steerer tube 108 and the head tube 116 at each of the respective ends of the head tube 116 to enable relative rotation between the steering column 100 and the bicycle frame, to enable the bicycle to be steered.

The integral portion 110 of the stem 102 is configured to be received within the fork steerer tube 108 to secure the stem 102 to the fork steerer tube 108. In the embodiment shown, the integral portion 110 is uniformly expandable. The integral portion 110 is configured to expand substantially uniformly in a radial direction to press against an interior wall of the fork steerer tube 108. In the embodiment shown, the integral portion 110 comprises a pair of opposing wedges 110a, 110b. Each of the wedges 110a, 110b comprises an angled or wedge-shaped surface. The wedges 110a, 110b are disposed along a longitudinal axis substantially parallel to a longitudinal axis of the fork steerer tube 108 when the integral portion 110 is received within the fork steerer tube 108. The wedges al 10a, 110b are movable relative to one another along the longitudinal axis. In the embodiment shown, the wedges 110a, 110b are connected by a threaded bolt 1 lOd. The second wedge 110b is integral to the first stem portion 102a and comprises an aperture through which the body of the threaded bolt 1 lOd may pass. The aperture is sized to prevent a head of the threaded bolt 1 lOd from passing through. The first wedge 110a is secured to the threaded bolt 1 lOd via threads disposed on the first wedge 110a. A distance between the first wedge 110a and the second wedge 110b along the longitudinal axis may be altered by relative rotation between the threaded bolt 1 lOd and the first wedge 110a (for example, by rotation of the bolt, which can be accessible in the folded configuration). The integral portion 110 also comprises at least one plate 110c which is in contact with the angled surface of both of the wedges 110a, 110b. As the distance between the wedges 110a, 110b along the longitudinal axis is decreased (in this case, decreased by tightening the bolt 1 lOd), the at least one plate 110c moves in an outwardly radial direction (as the plate contacts progressively wider parts of the angled surfaces) to press against the interior wall of the fork steerer tube 108. The opposite may be achieved by increasing a distance between the wedges 110a, 110b along the longitudinal axis. By spreading the contact between the integral portion 110 and the interior wall of the fork steerer tube 108 across the whole surface of the plate 110c, there is no single point of contact acting as a pivot point which can increase play and decrease stability at the handlebars 104.

A top of the fork steerer tube 108 is exposed above the head tube 116. A locking collar 118 is placed around the fork steerer tube 108 to apply preload (that is, compressive force) to the bearing 120 disposed at the top end of the head tube 116 and to the bearing 120 disposed at the opposing bottom end of the head tube 116. The locking collar 118 is also configured to be locked in place on the fork steerer tube 108 via a releasable locking mechanism, to ensure the preload applied to the bearings 120 is consistent. By providing a single component which can both apply preload to the bearings 120 and remain fixed in placed without additional components, a stack height (a height or distance by which the fork steerer tube 108 extends above the head tube 116) may be reduced. A reduced stack height may provide additional space within the internal space of the stem 102 for accommodating the retaining element 110 when the stem 102 is in the unfolded configuration.

In the embodiment shown, the top of the fork steerer tube 108 comprises an external thread configured to engage with an internal thread disposed on an internal circumferential surface of the locking collar 118. The desired preload may therefore be applied to the bearing 120 by rotating the locking collar 118 to the appropriate axial position on the fork steerer tube 108. However, that is not essential, and the locking collar 118 may alternative be disposed on the fork steerer tube 108 in any suitable manner, for example slid into position onto the fork steerer tube 108.

Once the locking collar 118 is placed in the correct position on the fork steerer tube 108 to apply the desired preload to the bearings 120, the locking collar 118 is secured in place on the fork steerer tube 108 via a releasable locking mechanism 122. The releasable locking mechanism 122 is shown in Figure 8C, which shows the locking collar 118 in greater detail.

In the embodiment shown, the locking collar 118 comprises an open or partial annulus having a first end and a second end. The first end and the second end of the open annulus shape are separated by a gap. That may allow the locking collar 118 to flex to be compressed to lock in place around the fork steerer tube 108, or to be expanded to be released from the fork steerer tube 108, driven by the releasable locking mechanism 122 which is configured to controllably vary a distance between the first and the second end of the locking collar 118. In the embodiment shown, the releasable locking mechanism 122 comprises a pinch bolt, although that is not essential and any suitable alternative may be used instead, such as a clasp or an eccentric cam lever. In the embodiment shown, the locking collar 118 comprises a plurality of notched or recessed portions 124 on an inner circumferential surface of the locking collar 118. That may enable the locking collar 118 to more easily flex to be compressed or expanded, in order to lock in place or be released from the fork steerer tube 108. Additionally or alternatively, one or more notched or recessed portions may be provided elsewhere on the locking collar 118 to aid flexure of the locking collar 118, for example on an outer circumferential surface of the locking collar 118. However, that is not essential, and the locking collar 118 may alternatively not comprise any notched or recessed portions.

The locking collar 118 also comprises one or more portions 126 configured to allow rotational force to be applied to the locking collar 118, for example manually by a user’s hand or via a tool. In the embodiment shown, the portions 126 comprise protrusions extending outwardly from an outer circumferential surface of the locking collar 118, although that is not essential. The portions 126 may alternatively comprise one or more recesses or depressions for receiving a tool or a user’s fingers to allow rotational force to be applied to the locking collar 118. Such recesses or depressions may additionally allow the locking collar 118 to flex more easily and may simultaneously provide the dual function of the notched portions 124 and the protrusions 126 described above. Alternatively, the locking collar 118 may not comprise any such portions.

Although described with respect to the folding bicycle steering column 100, it will be appreciated the locking collar 118 may equally be used in steering columns for non-folding bicycles. The reduced stack height may be particularly useful for racing purposes, for example on time trial bicycles, because it may increase an aerodynamic advantage of a rider by lowering a torso angle of the rider while riding. Similarly, although the integral portion 110 of the stem 102 is described in combination with the other features of the folding bicycle steering column 100, it will be appreciated a foldable bicycle stem may be provided with such an integral portion 110 without some or all of the other features of the foldable bicycle steering column 100.

In the embodiment shown, a wall of the stem 102 is joggled or stepped at or adjacent the lower end of the stem 102 adjacent the fork steerer tube 108, narrowing inward to decrease an internal diameter of the stem 102 at the end. The joggle or step provides the stem 102 with a wider portion and a narrower portion substantially adjacent one another, connected by the joggle or step. The narrower portion is configured to be received within the fork steerer tube 108 to enable the stem 102 to be secured to the fork steerer tube 108. In the embodiment shown, the narrower portion forms a part of the integral portion 110. The wider portion may provide additional space within the stem 102 for accommodating the retaining element 112 when the stem 102 is in the unfolded configuration 102. That may also provide additional rigidity to the stem 102, with the wider diameter providing a stiffening effect without significantly increasing a weight of the steering column 100. The joggle or step in the wall of the stem 102 also provides a substantial discontinuity in a width or diameter of the wall of the stem 102, which forms a shoulder or platform in the wall of the stem 102. A surface (for example a top surface) of the locking collar 118 may be configured to contact the should or platform formed in the stem 102 in use. For example, in the embodiment shown, the surface of the locking collar 118 comprises a lip configured to abut the shoulder or platform provided by the joggled wall of the stem 102. That may improve stability of the steering column 100 by resisting or inhibiting relative movement between the parts of the steering column 100 in use, and preventing the narrower portion received and secured within the fork steerer tube from forming a pivot point. In turn, that may provide greater dimensional stability and relative positioning between the handlebars and other rider contact points in use. However, it will be appreciated the stem 102 may not comprise a joggled or stepped wall.

The second stem portion 102b comprises a contact pin 128. The contact pin 128 is configured to contact a wear surface of the first stem portion 102a. The contact pin 128 is configured to prevent or inhibiting the walls of the first and second stem portions 102a, 102b from directly contacting one another when the stem 102 is in the unfolded configuration. That may reduce wear of the stem 102 itself and confine the wear to a smaller component which may be easily replaced. It will be appreciated multiple contact pins 128 may be provided, and/or the contact pin 128 may alternatively be provided on the first stem portion 102a and configured to contact a wear surface of the second stem portion 102b. However, that is not essential, and the stem 102 may not comprise a contact pin.

From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of bicycles and bicycle frames, in particular foldable bicycles and foldable bicycle frames, and which may be used instead of, or in addition to, features already described herein.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, and any reference signs in the claims shall not be construed as limiting the scope of the claims.