GB2613888A

GB2613888A - A crank assembly

Info

Publication number: GB2613888A
Application number: GB2118506.1A
Authority: GB
Inventors: Anthony Connell Richard
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-12-20
Filing date: 2021-12-20
Publication date: 2023-06-21
Anticipated expiration: 2041-12-20
Also published as: GB2613888B

Abstract

A crank assembly for a cycle, comprising: a crank arm 100 attachable to a crank axle 200 for driving rotation of the crank axle 200 about a first axis 60; a pedal 121 attached to the crank arm 100, the pedal 121 being rotatable about a second axis 62 parallel to the first axis 60, and further being slidingly movable relative to the crank arm along the second axis 62. Sensors 140, 142 may detect the position of the pedal thereby allowing control of for instance gear change. The sliding movement may be indexed.

Description

A CRANK ASSEMBLY

Field

The present application relates to a crank assembly, and in particular to a crank assembly for a cycle.

Background

With the exception of track bikes, almost all of the commercially available cycles employ mechanisms that require a user to perform certain functions by hand. For 113 example, a user may select an appropriate gear for a suitable cadence using a mechanical shifter, or to apply braking by squeezing a brake lever mounted on a handlebar. Not only the force applied by the user can be considerable, but the use of such hand-operated shifters and brake levers may also prevent the user from maintaining a firm grip on the handlebar.

EP2210804A discloses a hand-operated control device for controlling an electronic derailleur, where an appropriate gear can be selected by activating a non-contact switch provided on a brake lever. Such an embodiment may reduce the amount of operating force applied by the user during gear shifting. However, the user may nevertheless have to move his/her fingers from a normal riding position to activate the non-contact switch, thereby reducing the grip on the handlebar.

Another problem with hand-operated shifters or brake levers is that the actuating force is commonly transferred by Bowden cables that run externally from the handlebar, along the length of the bicycle frame to a rear derailleur, or a rear brake. Not only they are unsightly, but loose cables may also get caught, or knotted up, during riding and transportation. This problem is particularly prominent in collapsible or foldable cycles that are frequently carried around during crowded commutes.

Therefore, a non-hand-operated means for effecting gear selection and/or braking at a cycle is highly desirable.

Summary

The present invention offers a crank assembly at which a user may effect gear selection and/or braking by foot. Advantageously, by reducing or eliminating the need for hand operations, the user may maintain a firm grip on the handlebar at all times, thus improving the safety and quality of cycling. Moreover, the proximity of the crank assembly to the derailleurs and the rear brake assembly not only requires shorter lengths of cables, but it may also allow the cables to be concealed more easily.

According to a first aspect of the presently-claimed invention, there is provided a crank assembly for a cycle, comprising: a crank arm having a first end attachable to a crank axle for driving rotational movement in a crank axle about a first axis; a pedal attached to a second end of the crank arm, the pedal is rotatable about a second axis parallel to the first axis, and is slidingly movable relative to the second end of the crank arm along the second axis.

The cycle may be any pedal-powered cycle, for example monocycles, bicycles, tricycles, quadricycles, cargo cycles and recumbent cycles. The cycle may be powered by the user alone, or by a combination of user input and a motor, e.g. an electric bike.

Using a bicycle as an example, the crank axle may be referred to as a driving axle that is installed at a bottom bracket of the bicycle. The crank axle may be rotatable about the first axis, or otherwise known as a crank axis, that extends perpendicularly to the longitudinal axis of the bicycle. The crank axle may rotate with one or more front sprockets coaxially mounted thereon, for driving rotational motion in a corresponding rear sprocket set by a chain or a belt.

The pedal may comprise a spindle defining a second axis parallel to the crank axis. 30 The pedal may be rotatably attached to the second end of the crank arm by the spindle. Thus, the rider may push on the pedal to crank the crank axle in order to drive a forward movement of the cycle.

In conventional cycles, the pedal may only rotate about the second axis whilst movement in any other direction is constrained, e.g. the spindle in a conventional pedal only permits rotational movement in the pedal. This ensures all of the pedalling forces are precisely translated to crank the crank axles. In contrast, the spindle according to the present invention is configured to slidingly move through an aperture at the second end of the crank arm, thereby allowing the pedal to move relative to the crank arm along the second axis. Advantageously, such an arrangement allows the rider to perform additional functions by foot in addition to conventional pedalling, and in some cases removing the need for conventional Bowden cable connections.

Optionally, the crank assembly comprises a sensor arrangement arranged to sense an axial position of the pedal along the second axis, the sensor arrangement is configured to generate a signal corresponding to the axial position of the pedal. More specifically, the sensor arrangement may detect the sliding movement in the pedal as it slides along the second axis.

In some embodiments, the sensor arrangement may comprise a magnetic sensor and a magnet each attachable to one of the cycle and the pedal. In a preferred embodiment, a reed switch may be installed on the cycle frame for sensing the proximity of a rare earth magnet that is attached to the pedal, e.g. at an end of the slidable spindle. For example, the reed switch may sense a weakened magnetic field when the pedal is put in an axial position furthest away from the cycle frame, e.g. a default position during normal pedalling, and thus it does not generate a signal. Once the rider moves the pedal towards the cycle frame along the second axis to perform a particular function, the magnetic field as sensed by the reed switch strengthens, and once it exceeds a predetermined threshold the reed switch generates a signal to be transmitted to a controller or other electronic devices for carrying out the said function.

In some embodiments, other magnetic sensors such as Hall effect sensors may be used, particularly in applications where the precise pedal position along the second axis is required. In some other embodiments, the reed switch may be installed on the pedal for sensing the proximity of a rare earth magnet attached to the cycle frame, wherein the signal may be transferred to a controller or other electrical devices wirelessly or by physical wiring.

In some embodiments, the sensor arrangement may comprise other sensors such as optical sensors, infrared sensors and ultrasound sensors.

Optionally, the signal is configured to control a gear selector, wirelessly or by physical wires, thereby allowing gear selection to be controlled by the movement of the pedal along the second axis. The gear selector may comprise an electronic derailleur for the front and/or rear sprocket sets. Upon receiving the signal, the electronic derailleur may displace the drive chain, in a direction parallel to the first axis, to a plurality of gear positions each of which corresponds to a sprocket of the sprocket sets.

Optionally, the signal is configured to control a brake actuator, thereby allowing braking to be controlled by the movement of the pedal along the second axis. The brake actuator may comprise an electronic brake actuator for the front and/or rear brakes of the cycle, wirelessly or by physical wires. Upon receiving the signal, the electronic brake actuator may apply a braking force to a rim of the wheel or a brake disc to slow down the cycle. In some embodiments, the braking force may correspond to the amount of sliding movement in the pedal along the second axis.

Alternatively, the pedal is mechanically connectable to a gear selector and/or a brake actuator, whereby the movement of the pedal along the second axis is arranged to control gear selection and/or braking. More specifically, the pedal may be connected to a derailleur and/or a brake actuator by a Bowden cable, wherein the actuating force for the derailleur and/brake actuator may be directly applicable by the rider.

Optionally, the pedal is moveable between a first axial position and one or more further axial positions along the second axis. More specifically, the sensor may sense the pedal position at each of the first axial position and the further axial positions, and thereby generate a signal accordingly.

Optionally, the pedal is biased towards the first axial position by a biasing means. For example, the first axial position may be a default pedal position adopted during normal pedalling where the rider does not require to perform a function, thus, the biasing means may aid the pedal to be retained at the first axial position. In order to move the pedal from the first axial position to other further axial positions, the rider may overcome the biasing force to drive sliding movement in the pedal along the second axis. In a preferred embodiment, a compression spring may coextend inside the spindle and biases against the second end of the crank arm. Thus the biasing force may bias the pedal away from the second end of the crank arm, and towards the first axial position during normal pedalling.

Optionally, the pedal is sequentially moveable between the first axial position and the plurality of further axial positions along the second axis, wherein the crank 113 assembly further comprises an indexing arrangement for movably retaining the pedal at each of first axial position and the one or more further axial positions. For example, the first axial positional and the plurality further axial positions may each correspond to a particular derailleur position. Thus, sequential gear selection may be achieved by moving the pedal through the various axial positions in the pedal.

Optionally, the indexing arrangement may comprise a sprung ball retainer at the second end of the crank arm. The sprung ball retainer may configure to movably retain the pedal at the desired axial position by a notch provided at each of the first axial position and the plurality of further axial positions at the spindle. The retaining force imposed by the sprung ball retainer may be sufficient to overcome the biasing force from the biasing means, i.e. if a biasing means is also provided, and it may be overcome by the rider when a force is applied to move the pedal along the second axis.

Optionally, the crank assembly comprises a second crank arm attached to the crank axle opposite to the crank arm, wherein a second pedal is rotatably attached to a second end of the second pedal, and is moveable relative to the second end of the second crank arm along a third axis parallel to the first and second axes.

Such crank assembly may resemble a conventional crank assembly where two crank arms are provided on each side of the crank axle, and are substantially opposite to each other when viewed along the first axis. However, in contrast to conventional crank assemblies, such an embodiment may allow two different functions to be independently performed when the rider moves each of the pedal and the second pedal along respectively the second and third axes.

Optionally, the pedal and the second pedal are configured to control gear selection in opposite directions. For example, in a preferred embodiment, the pedal and the second pedal may each have a first axial position away from the cycle frame adoptable during normal pedalling, and a second axial position proximal to the cycle frame for effecting gear selection. Thus, the rider may opt to shift up by sliding the pedal from its first axial position to its second position, and to shift down by sliding the second pedal from its first axial position to its second position, or vice versa. The said gear shifting may be accomplished only by foot, and not 113 relying on hand-operated shifter and Bowden cable connections as found on conventional bicycles.

Optionally, the axial movements of the pedal and the second pedal are each configured to control gear selection at one of the front and rear gear sprockets or brake actuators of the cycle. More specifically, the pedal and the second pedal may be sequentially moveable between the various axial positions along their respective second and third axes, whereby the sliding movement in the pedal and the second pedal may allow the rider to effect gear selection respectively at a rear derailleur and a front derailleur, or vice versa. Alternatively, the axial movement in the pedal and the second pedal may allow the rider to apply a corresponding braking force, respectively at the front brake actuator and rear brake actuator, or vice versa.

According to a second aspect of the presently-claimed invention, there is provided a crank assembly for a cycle, comprising: a crank axle rotatable about a first axis, the crank axle is configured to drive forward movement of the cycle when rotating in a first direction; a freewheel comprises an inner rotor and an outer rotor coextending along the first axis, the freewheel is mounted on the crank axle by the inner rotor and is connectable to a brake actuator by the outer rotor; wherein the outer rotor is configured to disengage from the inner rotor when the crank axle rotates in the first direction, and to engage with the inner rotor when the crank axle is forced to rotate in a second direction opposite the first direction, thereby applying an actuating force to the brake actuator.

The freewheel may be any freewheel commonly used in rear sprockets set in cycle drivetrains, e.g. at the rear axle. More specifically, in convention cycles, the outer rotor of the rear axle freewheel only engages the inner rotor when the outer rotor and the crank axle rotate in the first direction, so as to translate the driving force in the crank axle to a rotational movement in the rear sprockets set. The outer rotor of the rear axle freewheel disengages from the inner rotor when the cycle is coasting, thus eliminating the need for the rider to keep pedalling whilst the cycle is still in motion.

113 The freewheel according to the present invention may be a freewheel provided on the crank axle and may only engage in a rotational direction opposite to the rotational direction that engages the rear axle freewheel. Thus, according to the present invention, the freewheel at the crank axle may only engage when the crank axle is forced to rotate in the second direction opposite the first direction, and thereby translating the rotation force in the second direction to an actuating force applicable to the brake actuator.

The brake actuator may be a rear brake actuator and/or a front brake actuator, thus in some embodiments, the rotation force applied at the crank axle in the second direction may be translated into a braking force applicable to the front and/or rear brakes of the cycle. The brake actuator may comprise a brake calliper for a rim brake or a disc brake.

Advantageously, such as arrangement may utilise a reversed pedal movement for controlling the braking of the cycle, thus reducing, or eliminating the need to apply braking force by hand via conventional Bowden cable connections. Not only a larger braking force may be applied by a more powerful muscles group, e.g. quadriceps and hamstrings in the rider's upper legs in comparison to the rider's fingers, but the rider may also maintain a firm grip on the handlebar at all times.

Optionally, the amount of actuating force applicable to the brake actuator is proportional to the force acting on the crank axle in the second direction.

In some embodiments, the outer rotor of the freewheel may be mechanically connectable to the brake actuator by one or more of a chain, a cable or a hydraulic system. In a preferred embodiment, the outer rotator comprises a sprocket that is connectable to the rear brake actuator by a chain. As the crank axle and the outer rotator is forced to rotate in the second direction, it tensions the chain and thereby translating the rotating force into an actuating force at the brake actuator.

A larger rotating force inputted in the second direction at the crank axle may result in a proportionally larger actuating force at the brake actuator.

In some other embodiments, the crank assembly may further comprise a sensor for sensing the angular displacement of the outer rotor and/or measuring the force applied on the crank axle in the second direction, the sensor may be configured to generate a signal for controlling the amount of actuating force applicable to the brake actuator. For example, the sensor may comprise a load cell configured to measure the rotational force applicable in the second direction at the crank axle or the outer rotor. Alternatively, it may comprise other sensors for monitoring the angular displacement in the outer rotor, such as optical sensors. The signal may be received by a front or rear electronic brake actuator for applying a proportional actuating force at the brake actuator.

In some embodiments, particularly in examples where a sensor is used, the amount of actuating force applicable to the electronic brake actuator may not be proportional to the force acting on the crank axle in the second direction. For example, the actuating force may be uniform regardless of the magnitude of the force acting on the crank axle in the second direction, or it may increase non-linearly with the increase of the said force.

Furthermore, the use of a sensor may allow the signal to be received by an electronic front brake actuator, by wire or wirelessly. That is, since the front brake actuator is distally positioned from the freewheel, such an arrangement is particularly suitable for controlling the front brake actuator without the use of a mechanical connection.

Optionally, the crank assembly further comprises a biasing means for biasing the outer rotor in the first direction, such that the outer rotor ceases applying the actuating force to the brake actuator once the force acting on the crank axle in the second direction is removed. More specifically, the biasing means may release the tension in at least a part of the mechanical connection between the outer rotor and the brake actuator when no force is applied at the crank axle in the second direction. The biasing means may be directly connected to the outer rotor, or by the mechanical connection, e.g. the chain, to bias the outer rotor in the first direction. Advantageously, such an arrangement may promptly ease the brake actuator as soon as the rider removes the force in the second direction.

According to a third aspect of the presently-claimed invention, there is provided a cycle, comprising the crank assembly of any one of the preceding claims, further 113 comprises a brake actuator and/or a gear selector controllable by the sliding movement of the pedal along the second axis or by the force applied on the crank axle in the second direction.

Optionally, the gear selection and/or brake actuation are controllable by the sliding movement of the pedal in absence of a direct mechanical connection. Thus, the Bowden cables as used in conventional bicycles for controlling such gear selection and/or brake actuation are absent. In some embodiments, the gear selection and/or brake actuation are controlled wirelessly by the sliding pedals. In some embodiments, the gear selection and/or brake actuation are controlled via physical wiring by the sliding pedals.

Optionally, the cycle comprises a monocoque frame that forms a load-bearing structure to which a rear wheel of the cycle is mounted onto, the monocoque frame at least partially encloses the gear selector and other drivetrain components that drive the rear wheel. In a preferred embodiment, the monocoque frame completely encloses the entire gear selector and other drivetrain components that drive the rear wheel. The monocoque frame may generally be defined as an exoskeleton frame and may form from two monocoque shells. The monocoque frame may shield the drivetrain components including the front and rear sprocket sets, as well as the drive chain that connects the two sprocket sets. Thus, not only the monocoque frame helps concealing the drivetrain components thus offering an additional layer of protection, it may shield the user from the grease and grit commonly associated with a bicycle drivetrain system.

Optionally, the monocoque frame comprises a channel extending along the longitudinal axis of the monocoque frame, the monocoque frame further comprises a subassembly to which a front wheel of the cycle is mounted onto, the subassembly having a guide frame slidably received inside the channel of the monocoque frame for varying the overall length of the cycle. The guide frame may extend in a longitudinal axis of the cycle and along a horizonal plane, whereby the relative sliding movement between the subassembly and the monocoque frame may allow the length of the cycle to be adjusted to different user sizes. The guide frame may alternatively extend at an angle to a horizonal plane, whereby the relative sliding movement between the subassembly and the monocoque frame may allow the height and the length of the cycle to be adjusted to different user sizes. The channel may be a receiving tube that coaxially extends with, and configured to slidingly receive, the guide frame, or it may be a guide rail extending parallel to the guide frame for slidingly receiving a protruded part of the guide frame.

Optionally, the monocoque frame further comprises a seat post, the seat post is arranged to extend through, and angled to, the channel of the monocoque frame in a ridable configuration, and is configured to be stowed in the channel parallel to the guide frame in a collapsed configuration. Thus, the channel of the monocoque frame may extend through the monocoque frame where one end is configured to receive the guide frame and the other for receiving the seat post in the collapsed configuration. More specifically, in the ridable configuration, the rider may ride on a seat of the seat post, whereby the monocoque frame bears the weight of the rider. In the collapsed configuration, the guide frame may be stowed in the channel with the seat post may be received in the guide frame such that the channel, the guide frame and the seat post may coextend along the longitudinal axis of the cycle.

According to a fourth aspect of the presently-claimed invention, there is provided a monocoque frame that forms a load-bearing structure to which a rear wheel of the cycle is mounted onto, the monocoque frame at least partially encloses a gear selector and other drivetrain components that drives the rear wheel; the monocoque frame comprises a channel extending along the longitudinal axis of the monocoque frame; a subassembly to which a front wheel of the cycle is mounted onto, the subassembly having a guide frame slidably received inside the channel of the monocoque frame for varying the overall length of the cycle.

Optionally, the monocoque frame further comprises a seat post, the seat post is arranged to extend through, and angled to, the channel of the monocoque frame in a ridable configuration, and is configured to be stowed in the channel parallel to the guide frame in a collapsed position.

Features from any one of the first to the fourth aspects of the present invention may be applicable with any other feature from the other aspects.

Brief Description of the Drawings

Certain embodiments of the presently-claimed invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a bicycle in a ridable configuration according to a first embodiment of the present invention; Figure 2 is a side view of the bicycle of Figure 1 in a collapsed configuration; Figures 3 and 4 are respectively a side view and a plan view of a crank assembly fitted to the bicycle as shown in Figures 1 and 2; Figure 5 is a plan view of a crank assembly adopting a different pedal position to that as shown in 4; Figure 6 is a plan view of a crank assembly showing the pedal of Figure 4 being put into a collapsed configuration; Figure 7 is a side view of a freewheel mounted to a crank axle according to an embodiment of the present invention; Figures 8A and 8B are respectively a side view and plan view of a brake actuating system where a braking force is applied; and Figures 9A and 9B are respectively a side view and plan view of brake actuating 5 system of Figures 8A and 8B where the braking force is removed.

Detailed Description

Collapsible bicycle comprising a monocoque frame Figures 1 and 2 are side views of a bicycle 10 in respectively a ridable configuration and a collapsed configuration according to a first embodiment of the present invention. The bicycle 10 is a collapsible bicycle where the overall length of the bicycle 10 can be varied to suit riders of different sizes in a ridable configuration as shown in Figure 1, as well as being put into a collapsed configuration as shown in Figure 2 during transportation.

Towards the front of the bicycle 10 there is provided a subassembly 22, comprising a front wheel 34 rotatably mounted onto a fork 24 by a front axle 36. The fork 24 having a steerer tube at its top end that extends through a headtube 26, wherein bearings are provided in the headtube 26 to aid relative rotation between the said steerer tube and the headtube 26. The steerer tube of the fork 24 is coupled to a handlebar stem 25 fixed attached to a handlebar (not shown). The handlebar stem 25 is partly enclosed in a stem sleeve 27 extending upwardly from the headtube 26. Thus, a rider may rotate the handlebar about the headtube 26 to steer the bicycle 10 into the desired direction.

The stem sleeve 27 is configured to pivot about a hinge 29 to convert between the ridable configuration and the collapsed configuration. More specifically, in the rideable configuration, the handle stem 25 extends at an angle to the longitudinal axis of the bicycle 10 and is locked in position by a hinged lever. On the other hand, the handle stem 25 is substantially parallel to the longitudinal axis of the bicycle 10 when the stem sleeve 27 of the bicycle 10 is put into the collapsed configuration. Such an arrangement reduces the overall height of the bicycle when it is collapsed.

The subassembly 22 further comprises an elongated guide frame 28 welded to the headtube 26. The guide frame 28 extends in a horizontal plane along the longitudinal axis of the bicycle 10. The guide frame 28 is of conventional tubular frame construction and may form from any suitable material. The phrase horizontal plane generally refers to a plane parallel to the horizon when the bicycle 10 is set on levelled ground, and may be substantially parallel to a line extending through the front and rear axle of the bicycle.

Referring to Figure 1, a rearward portion of the bicycle 10 comprises a monocoque frame 12 rotatably supported on a rear wheel 30 by a rear axle 32. The monocoque frame 12 forms a load-bearing structure of the bicycle 10 that is configured to distribute some of the weight of the rider (not shown) and the bicycle 10 to the rear axle 32. That is, the monocoque frame 12 is the only load-bearing member connected between a seat post 16 and a crank axle 200 of the bicycle 10 to the rear axle 32. The monocoque frame 12 may be formed from any suitable material such as steel, aluminium, and other composite materials such as a carbon fibre composite. The rear wheel 30 and the front wheel 34 are compact bicycle wheels each having an overall diameter of less than 350mm, commonly referred to as 12 or 14 inches wheels.

The monocoque frame 12 is formed from two monocoque shells joint together along a longitudinal centreline of the bicycle 10. As shown in Figure 1, the monocoque frame 12 fully encloses a rear sprockets set 40, a front sprockets set 50 and their respective derailleurs, as well as the drive chain 42 connecting the sprocket sets 40, 50.

The monocoque frame 12 further comprises a guide channel 14 extending along the longitudinal axis of the bicycle 10 and in the same horizontal plane as the guide frame 28. In the illustrated embodiment, the guide channel 14 extends internally through a front and rear opening of the monocoque frame 12. In some other embodiments, the guide channel 14 only extends through the front opening of the monocoque frame 12 whilst the rear end of the monocoque frame 12 is sealed, e.g. the guide channel 14 does not extend all the way through the monocoque frame in these embodiments.

The guide channel 14 is configured to slidingly receive the guide frame 28. The guide channel 14 has a cross-sectional profile complementary to that of the guide frame 28. The cross-section profiles of the guide channel 14 and the guide frame 28 are non-circular to prevent relative rotation between the subassembly 22 and the monocoque frame 12. By the sliding connection, the monocoque frame 12 joints the subassembly 22 to form the bicycle 10.

The overall length of the bicycle 10 can be adjusted by sliding the guide frame 28 113 along the guide channel 14 within a movement range to suit riders of different sizes. Furthermore, the guide channel 14 comprises a retaining means for movably retaining the guide frame 28 at any desired position within the said movement range.

For example, to suit a taller rider, the bicycle may be lengthened to its greatest extent by sliding the guide frame 28 towards a first end of the movement range, e.g. towards the front of the monocoque frame 12. On the other hand, as shown in Figure 2, the bicycle 10 may be put into the collapsed configuration by sliding guide frame 28 towards a second end of the movement range, which significantly shortens the overall length of the bicycle. To suit shorter or smaller riders, the guide frame 28 may be slide to a position between the two ends of the movement range.

As shown in Figure 2, the seat post 16 is configured to be inserted into the guide channel 14 through a rear opening of the monocoque frame 12 when the bicycle 10 is put into the collapsed configuration. More specifically, the seat post 14 may be received in, and coextends with, both the guide channel 14 and the guide frame 28. Such an arrangement reduces the overall height of the bicycle 10 when it is put into the collapsed configuration.

The bicycle 10 further comprises a support wheel 38 rotatably supported at the rear end of the monocoque frame 12. The support wheel 38 extends in the same plane as the front wheel 34 and the rear wheel 30, and is positioned upward of the rear wheel 30 as shown in Figures 1 and 2. When the bicycle 10 is put into the collapsed configuration as shown in Figure 2, the bicycle 10 may be pivoted about the rear axle 32 and be supported on both the rear wheel 30 and the support wheel 38. Thus, the rider may transport the bicycle 10 with relative ease by the support wheel 38 and the rear wheel 30.

Referring back to Figure 1, the front sprocket set 50 is mechanically connected to the rear sprocket set 40 by the drive chain 42. In use, a rider may push on a pedal 121 to rotate the crank axle 200 and the front sprocket set 50 in a first rotational direction 202. By the drive chain 42 and the rear sprocket set 50, the driving force is transferred to rear wheel 30 for driving forward motion in the cycle 10.

The drive chain 42 loops around a sprocket in each of the rear and front sprocket sets 40, 50, as well as engaging with a guide sprocket 70 and a tension sprocket 90 in a rear derailleur assembly. In the illustrated embodiment, the front sprocket set 50 comprises a single sprocket whilst the rear sprocket set 40 comprises four sprockets of different sizes, thus only the rear derailleur assembly is featured. In other embodiments, the front and rear sprocket sets may have any number of sprockets as required and may feature an additional front derailleur.

The guide sprocket 70 is configured to move in a direction parallel to the rear axle 32 so as to displace the drive chain 42 to other sprockets in the rear sprocket set 40. The tension sprocket 90, biased by a biasing means, is configured to maintain the tension in the drive chain as it loops around the various sprockets of the rear sprocket set 40.

Slidable pedal In conventional bicycles, a rider only pushes on the foot pedals to drive forward motion in the bicycle, and relies on a hand-operated gear selector for selecting an appropriate gear, or a hand-operated brake lever for slowing down the bicycle. In a second embodiment of the present invention, a crank assembly is provided which allows the rider to select gear or to apply braking when sliding the foot pedals sideways to the bicycle.

Figures 3 and 4 are respectively a side view and a plan view of a crank assembly according to a second embodiment of the present invention. The crank assembly is shown installed onto the collapsible bicycle 10 of Figures 1 and 2 as an example. However, such a crank assembly is also applicable to any suitable cycle. Figure 4 shows a truncated view of a crank axle 200 extending through the monocoque frame 12 along a first axis 60 and is rotatably supported on the monocoque frame 12 by suitable bearings (not shown). In relation to a conventional bicycle, the crank assembly can also be mounted onto a bottom bracket.

The crank assembly comprises a crank arm 100 having a first end 102 and a second end 104 opposite to the first end 102. The first end 102 of the crank arm 100 comprises a square tapered aperture through which an end of the crank axle 200, having a complementary profile, extends and is coupled thereto. Thus, the crank arm 100 may pivot about the first axis 60 to drive rotation movement in the crank axle 200. For simplicity, Figures 3 and 4 do not show a front sprocket set but it is nevertheless coaxially installed onto the crank axle 200.

The second end 104 of the crank arm 100 comprises a fork end defining a space in which a pivot block 108 is inserted. The pivot block 108 is pivotally connected to the fork end by a guide pin 106, which extends through both the fork end and the pivot block 108. Such an arrangement allows the pivot block 108 to rotate about the guide pin 106.

The pivot block 108 comprises a pivot block aperture through which a spindle 122 of a pedal assembly 120 extends. The spindle 122 defines a second axis 62 parallel to the first axis 60. The pedal assembly 120 further comprises a pedal 121 rotatably mounted on the spindle 122 by suitable bearings (not shown). Thus, similar to conventional crank assemblies, a rider may push on the pedal 121 in a direction perpendicular to the second axis 62 to rotate the crank axle 200, so as to drive forward motion in the bicycle 10.

By the pivoting movement in the pivot block 108, the pedal assembly 120 is pivotable about the guide pin 106 in a plane parallel to the second axis 62. The pivoting motion allows the pedal assembly 120 to convert between a ridable configuration as shown in Figure 4 and a collapsed configuration as shown in Figure 6. More specifically, in the rideable configuration, the spindle 122 extends substantially parallel to the first axis 60 so as to allow the rider to push on the pedal 121 to drive rotation in the crank axle 200. In contrast, in the collapsed configuration, the spindle 122 is oriented perpendicularly to the first axis 60. This feature is particularly beneficial for collapsible bicycles as the collapsed pedal in the collapsed configuration reduces their overall widths.

The crank arm 100 further comprises an internal sprung latch mechanism 150 for securing the pivot block 108 in the rideable configuration. That is, the sprung latch mechanism 150 comprises a spring-loaded latch receivable in a notch formed on pivot block, such that during normal pedalling the spindle 122 is kept parallel to the first axis 60. To convert the pedal assembly to the collapsed configuration, the rider may slide a toggle button 152 along the crank arm 100 to counteract the biasing force, thereby retracting the spring-loaded latch from the notch to free up the pivot block 108.

In contrast to conventional crank assemblies, the pedal assembly 120 is configured to slide from a first axial position to at least a second axial position along the second axis 62. More specifically, by the sliding movement, the rider may perform certain functions when the pedal assembly is put into the second axial position.

Referring to Figure 4, a guide slot 126 is opened through the spindle 122 along the second axis 62. The guide pin 106, which extends through the pivot block 108, also extends through the guide slot 126. Thus, by the relative sliding movement between the guide pin 106 and the guide slot 126, the pedal assembly 120 may slide through the pivot block aperture along the second axis 62.

The guide slot 126 generally defines the extent of the sliding movement in the pedal assembly 120. As shown in Figure 4, where the pedal assembly 120 is positioned at a first axial position, e.g. it is furthest removed from the monocoque frame 12, the guide pin 106 abuts one end of the guide slot 126. The first axial position may be referred to as a default pedalling position.

When the pedal assembly 120 slides towards the monocoque frame 12 to a second axial position as shown in Figure 5, the guide pin 106 abuts an opposite end of the guide slot 126 where further movement along the second axis 62 is prohibited. The stroke of the sliding movement in the given example ranges from 10 -15mm, but the stroke may be different in other embodiments. For example, the stroke of the sliding movement may correspond to a range of displacement in the corresponding derailleur or brake actuator.

In the illustrated embodiment, the spindle 122 comprises a hollow tube in which 113 a compression spring 124 is provided. More specifically, one end of the compression spring 124 abuts a closure member 130 and biases against the guide pin 106 at the other end. Thus, the compression spring 123 biases the pedal assembly 120 away from the monocoque frame 12. Such an arrangement ensures the pedal assembly 120 is always biased towards the first axial position during normal pedalling.

The closure member 130 is a screw threadedly installed in the hollow tube. By turning the closure member 130 it can reposition along the second axis relative to the hollow tube, and thereby varying the amount of biasing force applicable by the compressing spring 124. More specifically, the force required to move the pedal assembly 120 from the first axial position to the second axial position may be adjusted by turning the closure member 130 relative to the spindle 122. Alternatively, the closure member 130 may be a stopper fixedly attached to the hollow tube.

In some other embodiments, the pedal is sequentially moveable between the first axial position and a plurality of further axial positions along the second axis. For example, the plurality of further axial positions may comprise at least a second axial position and a third axial position each corresponding to a sprocket of the front sprocket set or the rear sprocket set. The crank assembly may further comprise an indexing arrangement for removably retaining the pedal at each of first axial position and the one or more further axial positions. Thus, sequential gear selection may be achieved by moving the pedal sequentially through the various axial positions.

Moreover, in these embodiments, the indexing arrangement may comprise a sprung ball retainer at the guide pin. The sprung ball retainer may configure to removably retain the pedal at desired axial positions by a notch provided at each of the first axial position and the plurality of further axial positions at the guide slot. The retaining force exerted by the sprung ball retainer may be sufficient to overcome the biasing force from the biasing means, i.e. if a biasing means is also provided, and it may be overcome by the rider when a force is applied to move the pedal along the second axis.

113 The spindle 122 further comprises a flange washer 128 arranged between the pedal 121 and the pivot block 108. As shown in Figure 5, the pedal assembly 120 may slide towards the monocoque frame 12 until the flange washer 128 makes contact with the pivot block 108, thereby it acts as an end stop that limits the axial movement of the pedal assembly 120. The flange washer 128 may be threadedly attached to the spindle 122 so that its axial position may be adjusted for varying the extent of movement in the pedal assembly 120.

In the illustrated embodiment, the crank assembly comprises a sensor arrangement 140,142 arranged to sense the axial position of the pedal 121 along the second axis 62. The sensor arrangement comprises a reed switch 142 that is installed on the monocoque frame 12 for sensing the proximity of a rare earth magnet 140 attached to a proximal end of the spindle 122. As shown in Figure 4, the reed switch 142 is arranged at a position on the monocoque frame 12 such that it aligns with the rare earth magnet 140 along the second axis 62 once in every crank revolution. The reed switch 142 is shown positioned on an exterior surface of the monocoque frame 12 in Figure 4, but it can be attached inside the monocoque frame in other embodiments.

As shown in Figure 4, when the pedal 121 is put in the first axial position during normal pedalling, e.g. the axial position that is furthest away from the monocoque frame 12, the reed switch 142 is put in an 'off' position and therefore it does not generate a signal. In order to perform a particular function, the rider may slide the pedal towards the monocoque frame 12 to the second axial position as shown in Figure 5. As such, the magnetic field as sensed by the reed switch 142 strengthens, and once it exceeds a predetermined threshold the reed switch 142 is put in an 'on' position and thus generates a signal to a controller or an electronic device for carrying out the said function. As the rider ceases applying force in the pedal 121 along the second axis 62, the compression spring 124 biases the pedal 121 back towards its first axial position suitable for normal pedalling.

In some other embodiments, the reed switch may be installed on the spindle for sensing the proximity of a rare earth magnet attached to the monocoque frame, wherein the signal may be transferred to a controller wirelessly, e.g. by a Bluetooth connection, or by physical wiring. In these embodiments, the reed switch may be energised by a battery or a capacitor, or by the rotating motion in the pedal assembly.

The use of the reed switch 142 is sufficient for monitoring the pedal movement across two axial positions, e.g. the first axial position as shown in Figure 4 and the second axial position as shown in Figure 5. For applications that require detection at more than two axial positions, or when the precise pedal position along the second axis is required, other magnetic sensors such as Hall effect sensors may be used in lieu of the reed switch. In some other embodiments, the sensor arrangement may comprise other sensors such as optical sensors, infrared sensors and ultrasound sensors.

In the illustrated embodiment, the signal is configured to control an electronic gear selector (not shown) such as a front electronic derailleur and/or a rear electronic derailleur respective for the front and/or rear sprocket sets. Thus, in contrast to known examples, the present invention allows gear selection to be controlled by the movement of the pedal 121 along the second axis 62. Upon receiving the signal, the electronic front and/or rear derailleur displaces the drive chain, in a direction parallel to the first axis 60, to a plurality of gear positions, each of which corresponds to a sprocket of the respective sprocket sets.

In the present example, a second crank arm (not shown) is attached to an end of the crank axle 200 opposite to the crank arm 100, wherein a second pedal (not shown) is rotatably attached to a second end of the second pedal, and is sliding moveable relative to the second end of the second crank arm along a third axis parallel to the first and second axes. More specifically, two crank arms are provided on each side of the crank axle 200, and are substantially opposite to each other when viewed along the first axis 60. Thus, the sliding movements in the pedal 121 and the second pedal along their respective second axis 62 and third axis allow two different functions to be independently performed.

In the illustrated embodiment, the pedal 121 and the second pedal are configured to control gear selection in opposite directions. For example, the pedal 121 and the second pedal may each have a first axial position distal to the monocoque frame 12 adoptable during normal pedalling, and a second axial position proximal to the cycle frame for effecting gear selection. That is, the rider may upshift by sliding the pedal from its first axial position to its second position, and downshifts by moving the second pedal from its first axial position to its second position.

In some other embodiments, the pedal 121 and the second pedal are each configured to control gear selection at one of the front and rear derailleurs. More specifically, the pedal 121 and the second pedal are sequentially moveable between a plurality of axial positions along their respective second and third axes, where each of the plurality of axial positions corresponds to a sprocket in the respective front and rear sprocket sets.

In some other embodiments, the signal is configured to control an electronic brake actuator, thereby allowing braking to be controlled by the movement of the pedal and/or the second pedal along their respective second and/or third axes. The electronic brake actuator may control the front and/or rear brakes of the cycle.

Upon receiving the signal, the electronic brake actuator may apply a braking force to the rim of the wheel or a brake disc to slow down the bicycle. In some embodiments, the braking force applicable may correspond to the amount of axial movement in the pedal and/or the second pedal along their respective second axis and third axis.

In some other embodiments, the pedal and/or the second pedal is mechanically connectable to a gear selector and/or a brake actuator, whereby the axial movement of the pedal and/or the second pedal is arranged to control gear selection and/or braking. For example, the pedal and/or the second pedal may be connected to a derailleur and/or a brake actuator by a Bowden cable, wherein the actuating force for the derailleur and/brake actuator may be directly applicable by the rider at the sliding pedal.

Advantageously, the sliding movement in the pedal 121 along the second axis 62 may be used for controlling braking and/or gear selection in a bicycle 10, thus reducing or eliminating the need for hand-operations from the rider.

Foot actuated brake actuator In conventional bicycles, a rider may push a pedal in the forward and downward directions to rotate the crank axle in a first rotational direction, so as to drive forward motion in the bicycle. During coasting, a freewheel installed at the rear axle decouples the rotation in the rear wheel from the rear sprocket set, thereby allowing the rider to cease pedalling whilst the bicycle is still in motion. That is, the freewheel at the rear axle only engages when the crank axle is rotating in the first rotational direction. However, the provision of the freewheel at the rear axle also means the rider cannot slow down the bicycle by simply pedalling in a reverse direction. As a result, most of the commercially available bicycles rely on the use of a hand-operated brake lever via Bowden cables to effect braking.

The present invention offers an inventive solution to allow the rider to control a brake actuator when applying force in a reversed pedalling direction, thereby reducing, or eliminating the need for hand-operated brake levers. More specifically, the present invention provides a second freewheel at the crank axle connectable with a brake actuator, which only engages when the crank axle is forced to rotate in a second rotational direction opposite the first rotational direction.

Figure 7 shows a freewheel 210 provided in a crank assembly according to a third embodiment of the present invention, using the bicycle 10 of Figures 1 and 2 as an example. However, such a crank assembly is also applicable to any suitable cycle. In relation to a conventional bicycle, the crank axle of the crank assembly can also be mounted onto a bottom bracket.

The freewheel 210 comprises an inner rotor 212 and outer rotor 214 coaxially mounted onto a crank axle 200. More specifically, since the inner rotor 212 is mounted onto the crank axle 200 by a spline connection, the inner rotor 212 rotates with the crank axle 200 when the latter rotates in both the first rotational direction 202 and the second rotational direction 204.

In contrast to the freewheels fitted on rear axles of conventional bicycles, the freewheel 210 only engages when the crank axle rotates in the second rotational direction 204, e.g. when the rider applies force in a reversed pedalling direction.

More specifically, during normal pedalling where the crank axle 200 rotates in a first rotational direction 202, the freewheel 210 disengages so that the inner rotor 212 and the crank axle 200 rotates relative to the outer rotor 214. That is, the outer rotor 214 is substantially stationary relative to the first axis 60. On the other hand, when the crank axle 200 rotates in the second rotational direction 204, the freewheel 210 engages, causing the outer rotor 214 to rotate with the inner rotor 212 and the crank axle 200.

In the illustrated example, the outer rotor 214 is a sprocket. The sprocket comprises a plurality of teeth for engaging with a chain. In some other embodiments, the outer rotor may be any type of rotor such as a pulley for engaging a cable.

Figures 8A and 8B show respectively a side view and a plan view of an activated brake actuation system according to the third embodiment of the present invention. Whereas Figures 9A and 9B show respectively a side view and a plan view of a deactivated brake actuation system according to the third embodiment of the present invention.

As shown in the figures, the freewheel 210 is mechanically connected to a rear brake actuator 220 by a chain 230. More specifically, the chain 230 having a first end connected to the monocoque frame 12, winds around the outer rotor 214 of the freewheel 210 and engages with the teeth of the said outer rotor 214, with its other end connected to a brake caliper 222 of the brake actuator 220.

As shown in Figures 8A and 8B, when the rider applies a force to crank the crank axle 200 in the second rotational direction 204, the outer rotor 214 engages with the inner rotor 212 and thus it is forced to rotate in the second rotational direction. By the teethed engagement, the rotational movement in the outer rotor 214 tensions the chain 230, and thereby applies an actuation force at the brake caliper 222. In response, the brake caliper 222 compresses a pair of brake pads 224 against the surface of a brake disc 226 to effect braking in the bicycle 10. Thus, the force applied to rotate the crank axle 200 in the second rotational direction 204 is translated to the braking force for slowing down the bicycle 10. Moreover, by the mechanical connection, the braking force applied to the brake actuator 220 is substantially proportional to the force applied at the crank axle 200 in the second rotational direction 204.

In some other embodiments, the brake pads 224 may instead be compressed against the rim of the rear wheel 30 during braking.

The brake pads 224 are configured to disengage from the brake disc 226 when the rider ceases applying force at the crank axle 200 in the second rotational direction 204, e.g. when braking is no longer required. As shown in Figures 9A and 9B, a biasing means 232 is provided to bias the outer rotor 214 to rotate in the first rotational direction 202 to facilitate a prompt disengagement. More specifically, the biasing means 232 is a tension spring having an end connected to the chain at a connection point 234 between the freewheel 210 and the brake actuator 220, and another end connected to the monocoque frame 12 of the bicycle 10. Essentially, the connection point 234 divides the chain 230 into a leading section 236 extending between the connection point 234 and the freewheel 210, and a trailing section 238 extending between the connection point 234 and the brake actuator 220.

The tension spring 232 is configured to apply a biasing force at the connection point 234 with a force component acting towards the brake actuator 220. The tension spring may extend substantially along the chain 230, or it may be angled to or offset to the chain to provide clearance. As such, the biasing force removes the tension in the trailing section 238 of the chain 230, thereby allowing the brake pads 224 to promptly disengage from brake disc 226.

By the biasing force imposed at the connection point 234, the leading section 236 of the chain 230 tensions and therefore biases the outer rotor to rotate in the first rotational direction 202.

In some other embodiment, the tension spring may directly connect between the outer rotor 214 and the monocoque frame 12 to bias the outer rotor in the first rotational direction 202. In these embodiments, the entire section of the chain 230 extending between the freewheel 210 and the brake actuator 220 may slack 113 when the force acting on the crank axle 220 in the second direction is removed.

In some embodiments, the biasing means may be other suitable springs such as a torsion spring.

During normal pedalling, e.g. when the rider cranks the crank axle in a first rotational direction as shown in Figures 9A and 93, the outer rotor 214 remains stationary relative to the first axis 60 during normal pedalling. Thus, no actuating force is applied to the brake caliper 220.

Advantageously, the freewheel allows braking to be achieved by a reversed pedalling input, thus reducing or eliminating the need for hand-operations from the rider.

Claims

Claims 1. A crank assembly for a cycle, comprising: a crank arm having a first end attachable to a crank axle for driving rotational movement in the crank axle about a first axis; a pedal attached to a second end of the crank arm, the pedal is rotatable about a second axis parallel to the first axis, and is slidingly movable relative to the second end of the crank arm along the second axis.
2. The crank assembly of claim 1, further comprises a sensor arrangement arranged to sense an axial position of the pedal along the second axis, the sensor arrangement is configured to generate a signal corresponding to the axial position of the pedal.
3. The crank assembly of claim 2, wherein the sensor arrangement comprises a magnetic sensor and a magnet each attachable to one of the cycle and the pedal.
4. The crank assembly of claim 2 or claim 3, wherein the signal is configured to control a gear selector, thereby allowing gear selection to be controlled by the movement of the pedal along the second axis.
5. The crank assembly of any one of the claims 2 to 4, wherein the signal is configured to control a brake actuator, thereby allowing braking to be controlled 25 by the movement of the pedal along the second axis.
6. The crank assembly of claim 1, wherein the pedal is mechanically connectable to a gear selector and/or a brake actuator, whereby the movement of the pedal along the second axis is arranged to control gear selection and/or 30 braking.
7. The crank assembly of any one of the preceding claims, wherein the pedal is slidingly moveable between a first axial position and one or more further axial positions along the second axis.
8. The crank assembly of claim 7, wherein the pedal is biased towards the first axial position by a biasing means.
9. The crank assembly of claim 7 or claim 8, wherein the pedal is sequentially moveable between the first axial position and the plurality of further axial positions along the second axis, wherein the crank assembly further comprises an indexing arrangement for movably retaining the pedal at each of first axial position and the one or more further axial positions.
10. The crank assembly of any one of the preceding claims, wherein the crank assembly comprises a second crank arm attached to the crank axle opposite to the crank arm, wherein a second pedal is rotatably attached to a second end of the second pedal, and is slidingly moveable relative to the second end of the second crank arm along a third axis parallel to the first and second axes.
11. The crank assembly of claim 10, wherein the axial movements of the pedal and the second pedal are configured to control gear selection in opposite directions.
12. The crank assembly of claim 10, wherein the axial movements of the pedal and the second pedal are each configured to control gear selection at one of the front and rear gear sprockets or brake actuators of the cycle.
13. A crank assembly for a cycle, comprising: a crank axle rotatable about a first axis, the crank axle is configured to drive forward movement of the cycle when rotating in a first direction; a freewheel comprises an inner rotor and an outer rotor coextending along the first axis, the freewheel is mounted on the crank axle by the inner rotor and is connectable to a brake actuator by the outer rotor; wherein the outer rotor is configured to disengage from the inner rotor when the crank axle rotates in the first direction, and to engage with the inner rotor when the crank axle is forced to rotate in a second direction opposite the first direction, thereby applying an actuating force to the brake actuator.
14. The crank assembly of claim 13, wherein the amount of actuating force applicable to the brake actuator is proportional to the force acting on the crank axle in the second direction.
15. The crank assembly of claim 13 or claim 14, further comprises a biasing means for biasing the outer rotor in the first direction, such that the outer rotor ceases applying the actuating force to the brake actuator once the force acting on the crank axle in the second direction is removed.
16. The crank assembly of any one of the claims 13 to 15, further comprises a sensor for sensing the angular displacement of the outer rotor and/or measuring the force applied on the crank axle in the second direction, the sensor is configured to generate a signal for controlling the amount of actuating force applicable to the brake actuator.
17. The crank assembly of any one of the claims 13 to 15, wherein the outer rotor of the freewheel is mechanically connectable to the brake actuator by one or more of a chain, a cable or a hydraulic system.
18. A cycle, comprising the crank assembly of any one of the preceding claims, further comprises a brake actuator and/or a gear selector controllable by the sliding movement of the pedal along the second axis or by the force applied on the crank axle in the second direction.
19. The cycle of claim 18, wherein the gear selection and/or brake actuation are controllable by the sliding movement of the pedal in absence of a direct mechanical connection.
20. The cycle of claim 18 or 19, further comprises a monocoque frame that forms a load-bearing structure to which a rear wheel of the cycle is mounted onto, the monocoque frame at least partially encloses the gear selector and other drivetrain components that drive the rear wheel.
21. The cycle of claim 20, wherein the monocoque frame comprises a channel extending along the longitudinal axis of the monocoque frame, the cycle further comprises a subassembly to which a front wheel of the cycle is mounted onto, the subassembly having a guide frame slidably received inside the channel of the monocoque frame for varying the overall length of the cycle.
22. The cycle of claim 21, further comprises a seat post, the seat post is arranged to extend through, and angled to, the channel of the monocoque frame in a ridable configuration and is configured to be stowed in the channel parallel to the guide frame in a collapsed configuration.113
23. A cycle, comprising: a monocoque frame that forms a load-bearing structure to which a rear wheel of the cycle is mounted onto, the monocoque frame at least partially encloses a gear selector and other drivetrain components that drives the rear wheel; the monocoque frame comprises a channel extending along the longitudinal axis of the monocoque frame; a subassembly to which a front wheel of the cycle is mounted onto, the subassembly having a guide frame slidable inside the channel of the monocoque frame for varying the overall length of the cycle.
24. The cycle of claim 23, further comprises a seat post, the seat post is arranged to extend through, and angled to, the channel of the monocoque frame in a ridable configuration, and is configured to be stowed in the channel parallel to the guide frame in a collapsed configuration.