Flywheel trainer

Abstract

A flywheel trainer 101 comprising a base 102 with a platform 103 for supporting a user. A rotatable body is configured to rotate relative to the base. The body comprises a central axle 117 connected t

Description

Field of the Invention The invention relates to a flywheel trainer. Background Weight training is a common type of strength training for developing the strength and size of muscles. It typically uses the force of gravity in the form of weighted bars, dumbbells or weight stacks in order to oppose the force generated by muscles. In recent times, the flywheel trainer has been developed to facilitate a new type of weight training. As shown in Figure 1, such a flywheel trainer 1 typically includes a handle 4 for pulling by a user 8, a flywheel 12 arranged away from the user 8 and for providing resistance to the user 8 when pulling on the handle 4, and a cord 16 extending between the handle 4 and the flywheel 12. To start using such a flywheel trainer, the user pulls on the handie thereby causing the flywheel to begin to rotate. Because the flywheel starts from a stationary position, the initial pull(s) on the handle require much larger pulling forces compared to when the flywheel is in motion. However, once the user has sufficiently developed a pulling rhythm, the exercise eventually becomes smoother and more manageable. At the beginning of use, the flywheel trainer is much more strenuous io use, and it can sometimes even be dangerous for users during this period. Indeed, it is not uncommon for users to tear a muscle or otherwise injure themselves at the start of training with a flywheel trainer, particularly when they are not properly warmed up’. It is against this background that the invention has been devised. Summary of the invention The invention resides in a flywheel trainer comprising: a base comprising a platform for supporting a user; a rotatable body configured to rotate relative to the base, wherein the rotatable body comprises a centra! axle and a flywheel connected to the central axle: a drive beit having a first end arranged to be accessible to a userand a second end opposite the first end that is coupled to the central axle, wherein the drive belt is arrangeable between a retracted configuration, in which the first end of the drive belt is arranged proximal to the platform and a portion of the drive belt is wound around the central axle, and an extended configuration, in which the first end of the drive belt is arranged distal from the platform and the drive belt is unwound from the centra! axle, and wherein the drive belt is configured such that pulling the first end of the drive belt moves the drive belt from the retracted configuration to the extended configuration, thereby causing rotation of the rotatable body; and a magnet arrangement comprising a first magnet arranged on the base and a second magnet arranged on the rotatable body such that the second magnet moves in and out of alignment with the first magnet as the rotatable body rotates, wherein the first and second magnets are configured to repel each other when aligned, so as to impart a torque to the rotatable body. These magnets therefore act to provide additional momentum ora rotational push to the flywheel when aligned, thereby reducing the extent to which the drive belt needs to be pulled by the user to get the flywheel in motion at the beginning of use. In an embodiment, the first and second magnets are arranged to align when the drive belt is in the extended configuration. In the extended configuration, the drive belt is (fully) unwound from the central axle. Because of this arrangement, it is much easier to get the flywheel moving at the beginning of use of the flywheel trainer. To obtain this effect, the user can start by (e.g., slowly) pulling the first end of the cord to such an extent that it is fully unwound from the central axle. In the fully unwound configuration, the magnets are arranged in alignment and since they repel each other, they provide a starting torque on the flywheel, causing it to rotate somewhat in either direction. As a result of this rotation, the cord is caused to wind around the central axle somewhat, and the cord is drawn at ieast partially towards the retracted position ready for a subsequent pull by the user. When the user does then pull (e.g., more forcefuily) on the first end of the cord, this reverses the rotation of the flywheel and causes the cord to first unwind from the central axle until it is fully unwound and in the extended position, and then start to wrap again around the central axle (but in the reverse direction), thereby causing the cord to move back towards the retracted position ready for another pull. Hence, to get the flywheel trainer going, the user does not need to start from the fully retracted position of the cord, and can instead start around the fully extended position thanks to the magnet arrangement. Because of this, the user doesn’t need to strain as hard at the start of use. Indeed, only a weak puli may be needed to get the flywheel trainer going at the start of exercise from this position. This therefore allows the user to build up momentum in the flywheel with ease at the start of using the trainer. This therefore reduces the risk of injury because a series of possibly straining pulls is not required to get the flywheel trainer moving. In an embodiment, the magnets are configured such that like poles of the magnets face each other when the magnets are aligned. In an embodiment, the platform has an upper side for a user to stand on and an underside opposite the upper side. The first magnet may be arranged on the underside of the platform. In an embodiment, the second magnet is arranged on the central axle. In particular, the centra! axle may have a first end arranged proximal to the platform and a second end distal to the platform. The second magnet may be arranged at the first end of the central axle. In an embodiment, the central axle comprises an axle body. Optionally, the axle body is frustoconical or conical in shape. In an embodiment, the centra! axle further comprises an extension portion. The extension portion may extend radially outward from the axle body to define a support on which the second magnet is arranged. The support may be flat and may extend parallel to the platform. In an embodiment, the second end of the drive belt is coupled to the central axle at a coupling location. The coupling location may be located at a narrow region of the frustoconical or conical axle body. The narrow region of the axle body may be arranged at the first end of the central axle while the wide end of the axle body may be arranged at the second end of the central axle. In an embodiment, the rotatable body is fully arranged under the platform. In an embodiment, the central axle extends along, and is arranged to rotate around, a central axis. The central axis may be transverse, and optionally orthogonal, to the platform. In an embodiment, the flywheel is arranged to rotate around a flywheel rotation axis. The flywheel rotation axis may be transverse, and optionally orthogonal, to the platform. Optionally, the central axis and the flywheel rotation axis are the same / refer to the same axis. In an embodiment, the flywheel is flat, and optionally disc-shaped. The flywheel may extend parallel to the platform. In an embodiment, the platform comprises a drive belt aperture through which the drive belt may extend to permit access to the first end of the drive belt for engagement by the user. In an embodiment, the flywheel trainer further comprises a pulley arrangement for optionally directing movement of the drive belt in a direction transverse to the platform. The pulley arrangement may comprise a first pulley, the drive belt optionally being arranged to run through the first pulley to guide the drive belt in a direction that is transverse to the platform. The pulley arrangement may further comprise a second pulley that optionally guides the drive belt between the first pulley and the central axle. The second pulley may be arranged such that the central axle is arranged between the second pulley and the first pulley. In an embodiment, the flywheel trainer further comprises a handle couplable to the first end of the drive belt. The handle may comprise a handle enclosure for containing and / or securing a first end of the drive belt. The handle may comprise a spool about which the drive belt is windable to adjust a length of free drive belt between the handle and the central axle (and hence adjust how far away from the platform the handle can be pulled by a user in use). The length of the free drive belt may be adjustable to suit the exercise that the user intends to do. The spool may be rotatable to wind the drive belt around the spool, and may be lockable to lock the length of free drive belt. Optionally, the handle comprises an actuator mechanism configured to lock and unlock the spool to permit rotation. The spool may be located within the handle enclosure and the actuator mechanism may comprise a button located on an outer surface of the handle enclosure for actuating the actuator mechanism to permit rotation of the spool. The spool may be located within the handle enclosure and the actuator mechanism may comprise a rotatable grip that is located on an outer surface of the handle enclosure and that is connected to the spool. The rotatable grip may be configured such that when the user rotates the grip the spool rotates. In one particularly preferred embodiment, the actuator mechanism takes the form of a ratcheted winding mechanism. The ratcheted winding mechanism may be configured: to wind the drive belt around the spool (i.e., spool the drive belt in and decrease the length of the free drive belt) when a user rotates the rotatable grip in one direction and to lock the spool (and hence lock the drive belt at its new length) in that position. When a user presses the button, the spool is unlocked, and the spool can rotate in the other direction, thereby allowing the drive belt to be unwound from the spool (i.e., un-spooled) by e.g., pulling the handle away from the platform, and thereby increasing / extending the length of the free drive belt. in an embodiment, the flywheel trainer further comprises a housing defining a housing enclosure containing the rotatable body. The platform may be provided by an upper wall of the housing enclosure. Optionally, the housing comprises a lower wail opposite the platform. The lower wall may define an opening shaped such that the flywheel disc can be removed from the central axle and the housing enclosure through said opening. The rotatable body may take the form of a flywheel arrangement comprising: the rotatable flywheel in the form of a flywheel disc arranged under the platform and having a flywheel rotation axis that is transverse to the platform; and the central axle extending along the flywheel rotation axis and connected to the flywheel disc such that the central axle rotates as the flywheel disc rotates. Since the flywheel disc may be arranged under the platform, the flywheel trainer can be made particularly compact. Furthermore, unlike conventional flywheel trainers, the flywheel trainer of the invention is used from above. As such, this flywheel disc trainer does not require much space to be used, indeed only the space of the trainer itself. The drive belt may have a first end for engagement by a user and a second end that is coupled to the central axle, so that the drive belt can be wound around and unwound from the centra! axle as the flywheel disc and central axle rotate. The platform may comprise an axle aperture that is arranged to expose a portion of the centra! axle for access by a user, to allow the user to rotate the central axle and flywheel disc. The user can access the exposed portion of the central axle from the platform to rotate it so as to rotate the central axle and the flywheel disc. This facilitates the start of rotation of the axle and the flywheel disc by either the foot or hand of the user. Just a few degrees of a turn is enough to accelerate the disc to get the flywheel spinning. In one embodiment, the axle aperture exposes an upward-facing surface of the central axle. The upward-facing surface may comprise a grippable material, such as a polymer, preferably a rubber material. In one embodiment, the central axle comprises a shaft and the upward-facing surface is provided on a cover arrangement that is arranged to cover an end of the shaft. The axle aperture may expose an upward-facing surface of the central axle. Preferably, the upward-facing surface is provided with a visual indicator for indicating a direction of rotation of the central axle. The visual indicator may be a spiral or arrow.. The exposed region may project above the platform. In a preferred embodiment, the flywheel rotation axis is orthogonal to the platform. In a particuiariy preferred embodiment, the central axle is conical or frusto-conical in shape. As the drive belt is wound around the central axle, that drive belt is ‘stacked’ along the conical shape. This provides a tapered ‘gear’ as the drive belt is stacked along the conical axle. In this embodiment, the second end of the drive belt is preferably coupled to the central axle at a coupling location, wherein the coupling location is located at a narrow region of the conical or frusto-conical axle. Providing the coupling location at this position means that when the drive belts is initially fully wound, the drive belt begins to unwind from the widest region of the conical axle. Wien the drive belt is fully unwound, it begins winding around the narrowest region of the conical axle. This provides an increasing degree of mechanical advantage when the user is pulling the drive belt from wound to unwound, decreasing the flywheel the user’s mechanical advantage as it drive belt unwinds, thus increasing the resistance of the flywheel trainer. In one embodiment, the drive belt takes the form of a cord. In one embodiment, the platform comprises a drive belt, aperture through which the drive belt extends to permit access to the first end of the drive belt for engagement by the user. The flywheel trainer may comprise a pulley arrangement for directing movement of the drive belt in a direction transverse to the platform. In one embodiment, the pulley arrangement comprises a first pulley. The first pulley may have a first pulley rotation axis that is transverse to the flywheel rotation axis. The drive belt may be arranged to run through the first pulley to guide the drive belt in a direction that is transverse to the platform. This arrangement allows for an even more compact arrangement of the flywheel trainer. Preferably the first pulley rotation axis is orthogonal to the flywheel rotation axis. In a preferred embodiment, the first pulley is arranged under the platform. This arrangement allows for an even more compact arrangement of the flywheel trainer. In one embodiment, the flywheel trainer comprises a second pulley. The second pulley may guide the drive belt between the central axle and the first pulley. The second pulley may be arranged such that the central axle is arranged between the second pulley and the first pulley. The second pulley allows for an even greater compactness of the flywheel trainer. The use of two pulleys also adjusts the resistance felt by the user using the flywheel trainer. This arrangement also facilitates the compact construction of the flywheel trainer, particularly when the first pulley is arranged below the platform. The drive belt may extend away from the central axle towards the second pulley in a first direction, and from the second pulley to the first pulley in a second direction opposite to the first direction. Preferably, the second pulley has a second pulley rotation axis that is substantially parallel to the flywheel rotation axis. In a preferred embodiment, the second pulley is arranged under the platform. This arrangement allows for an even more compact arrangement of the flywheel trainer. The flywheel trainer may further comprise a handle that is couplable to the first end of the drive belt. The handle may comprise a handle enclosure for containing and / or securing a first end of the drive belt. In these embodiments, the handle enclosure may comprise an inlet through which the drive belt passes when the handle is coupled to the first end of the drive belt. Said inlet is preferably surrounded by a buffer comprising a shock-absorbing material. The buffer advantageously reduces impact between the handle and the platform in the case where the handle is accidentally dropped by the user, and the handle is drawn towards the platform at speed. The buffer is preferably made of rubber. In a particularly preferred embodiment, the handle comprises a spool about which the drive belt is windable to adjust a length of free drive beit between the handle and the central axle. The spool is preferably rotatable to wind the drive belt around the spool, and lockable io lock the length of free drive belt. Optionally, the handle comprises an actuator mechanism configured to lock and unlock the spool to permit rotation. In this way, the length of drive belt between the handle and the central axial can be adjusted to a desired length by a user. Accordingly, the actuator mechanism, which may be actuatable by a button, facilitates quick and accurate adjustment of the drive belt length so as to suit the particular exercise being done by the user as well as to accommodate their particular stature. The winding spool is preferably a ratchet. The end portion of the drive belt is preferably fixedly attached to the Spool. Preferably, the spool is located within the handle enclosure. The actuator mechanism may comprise a button located on an outer surface of the handle enclosure. The spool arrangement described above allows for quick setting and fine tuning of the length of the available drive belt between the handie and the central axle. In this way, the user of the flywheel trainer can adjust the drive belt for any particular exercise being performed. The spool also provides a means for storing unused drive belt within the handle. The handles of the prior art instead leave drive belt to dangle down, which often gets in the way of the user when performing exercises and can even be dangerous to the user. The flywheel disc may be removably connected to the central axle. The user can advantageously add or remove flywheel discs to the flywheel trainer to suit the user and / or exercise being performed. At least some of the flywheel discs may have the different sizes and / or weights. Each flywheel disc is preferably arranged under the platform and preferably extends substantially parallel to the platform. A plurality of flywheel discs may be connected to the central axle such that each flywheel disc and the central axle rotate together when the user pulls on said handle. In one embodiment, the flywheel trainer comprises a housing defining an enclosure containing the central axle and the flywheel disc. An upper wall of the housing enclosure preferably defines the platform. The central axle may be rotatably fixed to the housing enclosure. The housing enclosure may also enclose the pulley arrangement. The housing may comprise a lower wall opposite the platform. In one particularly preferred embodiment, the lower wall defines an opening shaped such that the flywheel disc can be removed from the central axle and the housing enclosure through said opening. In one embodiment, the flywheel trainer further comprises an anchor for anchoring a first end of the drive belt. The first end of the drive belt can be anchored using a clip such as a carabiner. A handle with a pulley arrangement can be connected above the platform between the drive belt aperture and the anchor to provide an alternative use arrangement. The anchor is preferably provided on the housing. Features of any one aspect or embodiment of the invention may be used, alone or in appropriate combination, with other aspects and embodiments as appropriate. Brief Description of the Drawings Figure 1 has already been described above by way of the background to the invention and is a schematic view of a flywheel trainer of the prior art in use by a user. So that the invention may be better understood, reference will now be made by way of example only to the following drawings in which: Figure 2 is a first perspective view of the flywheel trainer of the invention. Figure 3 is a rear view of the flywheel trainer of Figure 2. Figure 4 is a cross-sectional side view of the flywheel trainer of Figure 3 along line A-A. Figure 5 is a second perspective view of the flywheel trainer of Figure 2, where the upper wall of the flywheel trainer has been removed. Figure 6 is a top-down view of the flywheel trainer of Figure 2. Figure 7 is a cross-sectional perspective view of the flywheel trainer of Figure 3 along iine A-A. Figure 8 is a side view of the flywheel trainer of Figure 2. In the figures, the flywheel trainer 101 is illustrated in an up-right configuration, i.e. in the orientation in which the flywheel trainer 101 would be used by a user, and in particular with the platform 103 facing upwards. Al! references to ‘upper’, lower’, ‘upward’, ‘downward’, ‘up’, ‘down’ etc are with reference to this up-right orientation. An x, y, z-co-ordinate system is used to refer to particular directions and axis, and the co-ordinate system is shown in the figures. The z-direction is a generally vertical direction, and the platform 103 of the flywheel trainer 101 generally extends in the x- and y-direction. Detailed Description Figures 2 to 8 show the flywheel trainer 101 of the invention. The flywheel trainer 101 comprising a base 102 comprising a platform 103 for supporting a user (not shown). The flywheel trainer 101 further comprises a rotatable body, a drive belt 116 and a magnet arrangement 112. The rotatable body is configured to rotate relative to the base 102. The rotatable body comprises a central axle 117 and a flywheel 114 connected to the central axle 117. The drive belt 116 has a first end arranged to be accessible to a user and a second end opposite the first end that is coupled to the central axle 117. The drive belt 116 is arrangeable between a retracted configuration, in which the first end of the drive belt 116 is arranged proximal to the platform 103 and a portion of the drive belt 116 is wound around the central axle 117, and an extended configuration, in which the first end of the drive belt 116 is arranged dista! from the platform 103 and the drive belt 116 is unwound from the central axie 117. The drive belt 116 is configured such that pulling the first end of the drive belt 116 moves the drive belt 116 from the retracted configuration to the extended configuration, thereby causing rotation of the rotatable body. The magnet arrangement 112 comprises a first magnet 112a arranged on the base 102 and a second magnet 112b arranged on the rotatable body such that the second magnet moves in and out of alignment with the first magnet 112a as the rotatable body rotates. The first and second magnets 112a, 112b are configured to repel each other when aligned, so as to impart a torque to the rotatable body. The magnet arrangement 112 therefore acts to provide additional momentum or rotational push to the flywheel 114 when the magnets 112a, 112b are aligned, thereby reducing the amount that the drive belt 116 needs to be pulled by the user to get the flywheel 114 in motion at the beginning of use. The components of the flywheel trainer 101 will now be described in more detail, starting with the base 102. As best shown in Figures 2, 3, 7 and 8, the base or housing 102 is made up of a substantially cuboid enclosure 120, although other shapes are possible. The base 102 has a width extending in a first axis x, a length extending in a second axis y and a depth extending in a third axis z. The base enclosure 120 is advantageously strong enough to stand on, but light enough to be easily portable. To this end, it is preferably made from a plastics material. The base enclosure 120 comprises an upper wail 122 defining the platform 103 and a lower wall 124 arranged thereunder. Between the upper and lower walls 122,124 extends an outer wall 126, which extends all the way around the cuboid base enclosure 120 to completely enclose the rotatable body within. In ether embodiments, a plurality of outer walls 126 may extend between the upper and lower waiis 122,124 on all sides of the base enclosure 120. The platform 103 also extends in the first axis x to define a width and in a second axis y to define a length. The xand y plane is referred to herein as the platform plane p (as shown in Figure 4). The platform plane p is preferably parallel to the floor (not shown), but may also be arranged at an inclined angle with respect to the floor for certain training needs. The user stands on the platform 103 when using the flywheel trainer 101. The user faces towards a front side 130 of the base 102. In this position, the user can grasp the first end of the drive belt 116 also arranged near the front side 130 of the base 102 and pull the first end of the drive belt 116 away from the platform 103. The user pulls on the drive belt 116 to use the trainer 101, and, as stated above, the drive belt 116 is attached to the central axle 117 at the second end thereof to provide resistance to the user pulling. In this example, the drive belt 116 takes the form of a cord. To facilitate grasping of the cord 116, the first end of the cord 116 is attached to a handle 104 that is engaged by the user. The handle 104 can be replaced by a different engagement means such as a harness or stirrup. When the cord 116 is arranged in the retracted configuration (not shown), the handle 104 is adjacent to the platform 103, whereas when the cord 116 is arranged in the extended configuration (such as shown in Figures 4 and 7), the handle 104 is more remote from the platform 103. When the user standing on the platform 103 pulls on said handle 104, the handle 104 is moved from the retracted configuration to the extended configuration, and back again. In particular, the handle 104, and hence the first end of the cord 116, is moved up and down (i.e., away and toward the platform 103) along a handle axis h. The angle 6 between the platform plane p and the handle axis h is transverse, i.e. at any angle less than 180° that is not 0° or 180°. The transverse angle 9 is preferably between 60° and 120°, more preferably between 70° and 110°, even more preferably between 80° and 100°, even more preferably between 85° and 95°, and most preferably substantially al 90°. As such, unlike conventional flywheel trainers, the flywheel trainer 101 of the invention is used from above. This flywheel trainer 101 therefore does not require much space to be used, indeed only the space of the trainer 101 itself is required for using the device. As best shown in Figures 4, 5 and 7, the base 102 houses the rotatable body in the form of a flywheel arrangement, which acts to provide resistance to the user when pulling on the cord 116. To this end, the flywheel arrangement comprises the rotatable flywheel 114 and the rotatable central axle 117. The flywheel 114 is connected to the central axle 117 such that the flywheel 114 and the central axle 117 rotate together in use. The second end of the cord 116 is connected to the central axle 117, such that the central axle 117 provides the connection between the cord 116 and the flywheel 114. The central axle 117 is configured to rotate when the user pulls the first end of the cord 116 away from the platform 103, and the flywheel 114 - coupled to the central axie 117 -provides resistance to this pulling. The flywheel arrangement is arranged within the base 102 and fully beneath the platform 103. This advantageously means that there is no interaction between the spinning flywheel arrangement and the user when the user is using the flywheel trainer 101. The central axie 117 is rotatably fixed to the base enclosure 120 such that the central axle 117 is rotatable with respect to the base enclosure 120. To this end, the central axie 117 is mounted on ball bearing races fixed into the upper and tower walls 122, 124 of the base enclosure 120. In particular, the first or upper end 156 of the central axle 117 is rotatably mounted on the upper wall 122 while the second or lower end 154 of the central axle 117 (i.e., opposite the first or upper end 156) is rotatably mounted on the lower wall 124. In this example, the central axle 117 has a frusto-conical axle body and has a wider radius at the lower end 154 compared to the upper end 156. In other embodiments, the axle body may be conical, or even cylindrical. The central axle 117 is arranged substantially in the centre of the base enclosure 120, i.e. under the centre of the platform 103. The central axle 117 extends along, and is arranged to rotate around, a central axis a. The angle rp between the platform plane p and the central axis a is transverse and preferably substantially 90° as this facilitates the winding of the cord 116 around the central axle 117. The second end of the cord 116 is securely connected to the central axle 117 at a coupling location. The coupling location is at the narrower upper end 156 of the conical central axle 117. To this end, an anchor hole is provided in the axie 117 at the narrower upper end 156 of the cone through which the cord 116 is passed. A knot or other movement stop feature 136 is used to secure the cord 116 in place on the other side of the central axle 117. When the cord 116 is in the retracted configuration, the cord 116 is most wound around the central axle 117. in this configuration, the cord 116 spirals down around the central axle 117 from the coupling location at the top - i.e., at the narrower region 156 of the central axle 117 - to the bottom of the central axle 117 - i.e., at the wider region 154 of the central axle 117. When the handle 104 is pulled away from the platform 103 by the user, the cord 116 is caused to unwind from the central axle 117, thereby causing the central axle 117 to rotate. In particular, the cord 116 begins unwinding from the lower region 154 of the conical axie 117. Since this region is wider, it provides a greater degree of mechanical advantage for the user when pulling the cord 116 away from the platform 103. If the handle 104 is pulled hard enough, the cord 116 will eventually be fully unwound from the conical axle 117, i.e., in the extended configuration (shown in Figures 4 and 7). From the fully unwound configuration, the cord 116 can then be rewound around the centra! axie 117, thereby drawing the axle 117 back towards the platform 103. In particular, the cord 116 is rewound around the central axle 117 from the narrower upper region 156 of the conical axle 117 first, before then extending downwards and around the broader and broader lower sections 154 of the central axle 117. In this way, the flywheel arrangement beneficially provides more and more resistance to the user as the handle 104 is drawn back to the platform 103. In the above ways, the conical central axle 117 can be understood to act as a varying 'gear’. The flywheel 114 is best shown in Figure 7. As stated above, the flywheel 114 is connected to the central axle 117 such that the central axle 117 and the flywheel 114 rotate together. In particular, the central axle 117 is connected to the lower end 154 of the flywheel 114. In this example, the flywheel 114 is flat and round (i.e., disc-shaped) and hence referred to below as a flywheel disc 114, but in other examples the flywheel 114 may have other shapes. The flywheel 114 has a larger diameter than the centra! axle 117. The flywheel 114 is also preferably made of steel, which is relatively light compared to a static lifting weight. In these ways, when the cord 116 is pulled from the centra! axle 117, the flywheel 114 provides significant resistance to the user. The fly wheel disc 114 has a flywheel rotation axis f about which it is arranged to rotate. The flywheel rotation axis is transverse to (i.e. non-parallel to) the platform 103, In this example, the flywheel rotation axis f is orthogonal to the platform plane p, so that the flywheel 114 is arranged substantially parallel to the platform plane p. The flywheel rotation axis f and the central axis a may therefore be the same. Since the flywheel disc 114 is arranged under and substantially parallel to the platform 103, the flywheel trainer 101 can be made very compact, light and therefore easy to store. When the user pulls on the handle 104, the flywheel 114 provides resistance to the user. If the handle 104 is pulled hard enough, and the cord 116 is fully unwound from the centra! axle 117, momentum built up in the flywheel 114 will ensure the central axle 117 continues to rotate. Because of this, the cord 116 will then start to (re-)wind around the central axle 117, but in the reverse direction. This in turn draws the handle 104 back towards the platform 103, ready forthe user’s next pull. The flywheel disc 114 is removably attached to the lower end 154 of the central axle 117. To this end, the flywheel disc 114 is provided with a central disc aperture 170 extending therethrough. Likewise, the lower end 154 of the central axle 117 is provided with a corresponding axle opening 172. A fastening 174 such as a bolt or screw is inserted through the central disc aperture 170 in the flywheel disc 114 and is received in the axle opening 172 in the central axle 117 to removably secure the two together. The lower wall 124 of the base enclosure 120 defines an opening 150 shaped such that the flywheel disc 114 can be removed from the central axle 117, and hence the base enclosure 120, through said opening 150. The lower wall 124 is preferably shaped so that the opening 150 is at least as large as the flywheel disc 114. Furthermore, the cord 116 can be changed through the opening 150, for example when it shows signs of wear. To this end, the opening 150 provides access to the central axle 117. To remove the flywheel disc 114, a user undoes the fastening 174 through the opening 150 in the lower wall 124, and separates the flywheel disc 114 from the central axle 117 and removes it from the base 102 out of the opening 150. The same or a replacement flywheel disc 114 can then be fixed to the centra! axle 117 using the fastening 174. Before describing the magnet arrangement 112, the operation of the flywheel arrangement during Tull’ use will first be explained. In an initial configuration, corresponding to the (fully) retracted configuration of the cord 116, the second end of the cord 116 is wound around the central axle 117. When the user pulls on the first end of the cord 116 along the handle axis h (e g., via the handle 104), the central axle 117 and the flywheel disc 114 are caused to rotate together. The flywheel disc 114 spins up to a speed determined by the strength of the pull by the user. As the cord 116 unwinds from the centra! axle 117, the first end of the cord 116 is moved away from the platform 103. If the pull of the user is hard enough, the cord 116 will eventually completely unwind from the central axle 117 (into the (fully) extended configuration) and the built-up momentum in the flywheel disc 114 will ensure the disc 114 and the central axle 117 keep spinning, thereby causing the cord 116 to wind back around the central axle 117 but in the opposite direction. As the cord 116 winds back around the central axle 117, the second end of the cord 116 is pulled back down towards the platform 103 along the handle axis h until the second end of the cord 116 is wound around the central ax!e 117 and the cord 116 is arranged again in the (fully) retracted configuration, ready for another stroke by the user. The flywheel 114 uses its stored kinetic energy to pull the cord 116 back in with approximately half the original outward pulling force. As the cord 116 re-winds, the user’s arms are pulled back towards the platform 103. The user may need to resist this return movement by pulling against the cord 116: the user’s resistance slows the rotation of the flywheel 114 until it comes to a stop. The lower end 154 of the stroke is therefore governed by the user’s strength in resisting the return movement. The more momentum that is imparted to the flywheel 114 in the initial pulling stroke, the greater the resistance that is needed to bring the flywheel 114 to a stop. The degree of resistance is therefore infinitely variable, and is driven by the user; the harder the user pulls initially, the greater the momentum in the flywheel 114, the more resistance is needed to stop the fly wheel 144 and end the stroke. The magnet arrangement 112 will now be described, with reference to Figures 4, 5 and 7. As stated above, the magnet arrangement 112 beneficially assists in building the flywheel’s momentum at the beginning of use, thereby avoiding user straining at this time. The first magnet 112a is arranged within the base enclosure 120 and fully underthe platform 103. In particular, the first magnet 112a is attached to the underside of the platform 103 or upper wall 122 of the base enclosure 120, i.e., opposite the upper side that the user stands on. In particular, the first magnet 112a is arranged centrally in the fly wheel trainer 101, between the central axle 117 and a rear side 132 of the base 102. The underside of the first magnet 112a that faces downwards is exposed. The second magnet 112b is also arranged within the base enclosure 120 and fully under the platform 103. In particular, the second magnet 112b is arranged on the central axle 117, at the upper end 156 of the central axle 117 proximal to the upper wall 122, In more detail, the central axle 117 is provided with an annular extension portion that extends radially outward from the axle body at the upper end 156 to define an annular support 142. The second magnet 112b is arranged on top of the annular support so that the upper side of the second magnet 112b that faces upwards is exposed. The annular support 142 is substantially flat and extends substantially parallel to the platform 103. In this example, the first and second magnets 112a, 112b are flat and circular (i.e., disc-shaped) and are arranged so that they extend substantially parallel to the platform 103. in other embodiments, the magnets 112a, 112b may have other suitable shapes and / or arrangements. The central axle 117 and the support 142 are connected together and hence rotate together. As such, as the centra! axle 117 rotates, the second magnet 112b also rotates. In particular, the second magnet 112b is fixed to one (relatively small) sector of the annular support 142, such that as the central axle 117 rotates, the second magnet 112b goes in a circular path (parallel to platform plane p) around the central axle 117. In this x-y plane, the second magnet 112b may have a dimension (e.g., a diameter or width etc.) that is substantially the same or less than the radial thickness of the annular support 142 (i.e., the radial distance between the outer and inner boundaries thereof). In this way, the second magnet can be securely fixed to the annular support 142. In one position on the circular path, the second magnet 112b is arranged centrally in the flywheel trainer 101, between the central axle 117 and the rear side 132 of the base 102, such that the underside of the first magnet 112a and the upper side of the second magnet 112b are proximal to each other, and are optionally even touching in this position. Here, the first and second magnets 112a, 112b can therefore be understood as being ‘in alignment’. In any other position of the second magnet 112b, the first and second magnets 112a, 112b can be understood as being 'out of alignment’. Therefore, as the central axle 117 rotates, the second magnet 112b is moved in and out of alignment with the first magnet 112a as it is moved in its circular path around the central axle 117. Importantly, the first and second magnets 112a, 112b are arranged such that they repel each other when in alignment. To this end, the magnets 112a, 112b may be arranged such that like poles of the magnets 112a, 112b face each other when the magnets 112a, 112b are aligned. In other words, the underside of the first magnet 112a and the upper side of the second magnet 112b may have the same pole, i.e., they may be both north poles or both south poles. As such, the magnets 112a, 112b cause the flywheel 114 to rotate with momentum when aligned together. In a preferred embodiment, the flywheel trainer 101 is configured such that the first and second magnets 112a, 112b are aligned when the cord 116 is arranged in the (fully) extended configuration (i.e., when the cord 116 is fully unwound from the central axle 117) (as shown in Figures 4 and 7). Because of this arrangement, it is much easier to get the flywheel 114 moving at the beginning of use of the flywheel trainer 101. To obtain this effect, the user can start by (e.g., slowly) pulling the first end of the cord 116 to such an extent that it is fully unwound from the central axle 117. In the fully unwound configuration, the magnets 112a, 112b are arranged in alignment and since they repel each other, they provide a starting torque on the flywheel 114, causing it to rotate somewhat in either direction. As a result of this rotation, the cord 116 is caused to wind around the central axle 117 somewhat, and the cord 116 is drawn at least partially towards the retracted position ready for a subsequent puli by the user. When the user does then pull (e.g., more forcefully) on the first end of the cord 116, this reverses the rotation of the flywheel 114 and causes the cord 116 to first unwind from the central axle 117 until it is fully unwound and in the extended position, and then start to wrap again around the central axle 117 (but in the reverse direction), thereby causing the cord 116 to move back towards the retracted position ready for another pull. Hence, to get the flywheel trainer 101 going, the user does not need to start from the fully retracted position of the cord 116, and can instead start around the fully extended position thanks to the magnet arrangement. Because of this, the user doesn’t need to strain as hard at the start of use. Indeed, only a weak pull may be needed to get. the flywheel trainer 101 going at the start of exercise from this position. This therefore allows the user to build up momentum in the flywheel with ease at the start of using the trainer 101, This therefore reduces the risk of injury because a series of possibly straining pulls is not required to get the flywheel trainer 101 moving. The flywheel trainer 101 further comprises a pulley arrangement to guide the movement of the cord 116 with in the enclosure 120. The pulley arrangement comprises first and second pulleys 118,180, which will now be described, with reference to Figures 4 and 7. The platform 103 defines a cord aperture 134, through which the cord 116 extends vertically, i.e. along the z axis, between the handle 104 and the pulley arrangement, in particular the first pulley 118. In other words, the cord 116 enters and exits the base enclosure 120 through this cord aperture 134. The cord aperture 134 is preferably surrounded by a polished metal eye in the upper wall 122 of the base enclosure 120, which acts to reinforce the aperture 134. The cord aperture 134 is arranged away from the centre of the platform 103 towards the front side 130 of the base 102. This arrangement of the cord aperture 134, and hence the handle 104, facilitates the gripping of the handle 104 by the user when standing on the platform 103 and facing towards the front 130 of the base 102. The first pulley 118 is configured to direct the cord 116 between the handle 104 and towards the flywheel arrangement, and is arranged directly below the cord aperture 134 within the base enclosure 120, and fully under the platform 103. The first pulley 118 is rotatably fixed to the base enclosure 120 such that the first pulley 118 is rotatable with respect to the base enclosure 120. To this end, the first pulley 118 takes the form of a roller that is mounted on ball bearings fixed to the base enclosure 120. The first pulley 118 is arranged vertically and its rotation axle extends in the x-axis parallel to the platform plane p. The first pulley 118 therefore guides the cord 116 from transverse to the platform 103 to parallel to the platform 103. The second pulley 180 is configured to direct the cord 116 between the first pulley 118 and the central axle 117, and is arranged within the base enclosure 120 and fully under the platform 103. In more detail, the second pulley 180 is arranged away from the central axle 117 towards a rear side 132 of the base 102 opposite the front side 130. In this way, the central axle 117 is arranged between the first and second pulleys 118,180 across the length of the base 102. As such, the cord 116 extends away from the first pulley 118 and past the central axle 117 towards the second pulley 180, before being directed back towards the central axle 117, as best shown in Figure 5. The second pulley 180 is rotatably fixed to the base enclosure 120 such that the second pulley 180 is rotatable with respect to the base enclosure 120. To this end, the second pulley 180 takes the form of a roller that is mounted on ball bearings. The second pulley 180 is arranged horizontally and its axle extends in the z-axis perpendicular to the platform plane p. The handle 104 is best shown in Figures 2, 3 and 6. The handle 104 comprises a handle enclosure which is substantially triangular. The handle enclosure defines an upper section in the form of a handlebar 188 that extends substantially straight such that it can be arranged to substantially extend in the x and y axis, i.e. parallel to the platform plane p. The handlebar 188 defines two hand grips 190 for being gripped by the user at either side thereof. In this way, the handlebar 188 is a multi-grip handle that gives the user a comfortable anchor to the cord 116, thereby providing maximum purchase in a variety of hand configurations. The handle enclosure extends downwards and inwards from either side of the handlebar 188 to a lowermost section of the handle 104. The handle 104 comprises an inlet 194 defined in the handle enclosure at the lowermost section of the handle 104. The cord 116 passes into the handle enclosure through said inlet 194. Said inlet 194 is surrounded by a buffer 194a comprising a shock-absorbing material preferably rubber. The buffer 194a advantageously reduces impact between the handle 104 and the platform 103 in the case where the handle 104 is accidentally dropped by the user, and the handle 104 is drawn towards the platform 103 at speed. The handle 104 further comprises a spool 195 in the form of a clockwise ratchet that is arranged within the handle enclosure, towards the lowermost section of the handle 104. The spool 195 is rotatably fixed to the handle enclosure such that the spool 195 is rotatable with respect to the base enclosure 120. However, the handle 104 is also provided with a locking mechanism or stop (not shown) that is able to lock the spool 195 to prevent it from rotating. The first end of the cord 116 is securely connected to the spool 195 and the cord 116 is windable around the spool 195. To this end, an anchor hole (not shown) is provided in the spool 195 through which the cord 116 is passed. A knot or similar feature (not shown) is used to secure the cord 116 in place on the other side of the spool 195. To facilitate the changing of the cord 116, the handle enclosure defines an access point (not shown) that is openable to allow a user to access the anchor hole. When the spool 195 is allowed to rotate, i.e. when the stop is not in use, the cord 116 unwinds from the spool 195. To facilitate this, the user may pull the handle 104 away from the platform 103, thereby causing the cord 116 to unravel from the spool. In this way, the length of the cord 116 between the handle 104 and the base 102 can be changed. The length of cord 116 between the handle 104 and the central axial can therefore be elongated to a desired length by a user. To control whether the spool 195 is allowed to rotate or not, there is an actuator mechanism comprising e.g. a button 196 provided on a back side 198 of the handie 104. When the button is pressed, the spool 195 is free to rotate, and the cord 116 unravels freely such that the total length of the cord 116 between the handle 104 and the base 102 is increased to the desired length. When the button is released, the stop prevents the spool 195 from rotating and the length ofcord 116 between the handle 104 and the base 102 is fixed. Accordingly, the button facilitates quick and accurate adjustment of the cord length so as to suit the particular exercise being done by the user as well as to accommodate their particular stature. The actuator mechanism may also comprise a rotatable grip 198a provided on a back side 198 of the handle 104. The rotatable grip 198a is connected to the spool 165 such that when the user winds the rotatable grip, the spool 195 spins and the cord 116 wraps around the spool thereby shortening the cord length. To this end, the actuator mechanism may take the form of a ratcheted winding mechanism. The ratcheted winding mechanism may be configured to wind the cord 116 around the spool 195 to shorten the cord length, when a user rotates the rotatable grip 198a in one direction and to lock the spool 195 (and hence secure the cord 116) in that position. When a user presses the button 196, the spool 195 is unlocked, and the cord 116 can be unwound from the spool (i.e., un-spooled) to elongate the cord length. As shown in Figures 4 and 6, the trainer 101 may be provided with an anchor 199 for anchoring the first end of the cord 116 thereto. The anchor 199 is provided as an attachment feature at the front of the housing 102, and in this example is a stainless steel loop. The first end of the cord 116 can be anchored to the anchor 199 using a clip such as a carabiner, instead of being anchored to the handle 104. In this case the handle 104 as shown in Figures 2 to 8 can be replaced with a different handle 104 having a pulley arrangement. The different handle 104 is arranged so that the cord 116 runs through the pulley arrangement, with the pulley arrangement located above the platform 103 between the cord aperture 134 and the anchor 199. This provides an alternative use arrangement with approximately double the resistance of the arrangement of Figures 2 to 8. As best seen in Figure 6, the platform 103 is provided with feet-indicator features 146 so as to guide the user as to where to stand with respect to the handle 104. Each feet-indicator feature 146 is arranged at a suitable distance apart on opposing lateral sides of the platform 103. The width of the platform 103, and hence the base 102, preferably corresponds with the outer lateral limits of the feet-indicator feature 146. Likewise, the length of the platform 103, and hence the base 102, preferably corresponds with the uppermost and lowermost limits of the feet-indicator feature 146. In this way, the base 102 can be made as compact as possible. The feet-indicator feature 146 may be provided with a grip so as to prevent the user from slipping on the platform 103. To this end, rubber grips may be used. Although specific embodiments have been described above, it would be apparent to the skilled person that modifications and variations are possible without departing from the spirit and scope of the invention, which is defined by the appended claims. As such, the appended claims intend to cover any such embodiments. Further, it would be apparent to the skilled person that many features described in relation to particular embodiments are combinable and envisaged for combination with features described in relation to other embodiments. For example, the first and second pulleys 118, 180 may be arranged in different locations. In other embodiments, the second pulley 180 may be omitted, such that the cord 116 extends directly between the first pulley 118 and the central axle 117 within the base enclosure 120. In another embodiment, the flywheel trainer 101 comprises a plurality of flywheel discs 114 secured to the central axle 117. By altering the number of flywheel discs 114 used, the user can adjust the resistance of the flywheel trainer 101 to match their needs. In one embodiment, the handle 104 is provided with an additional pulley (not shown). As best seen in Figures 6 and 7, the outer wall 126 of the base enclosure 120 near the front side 130 of the platform 103 is provided with a steel loop 199 that extends away from said outer wall 126, i.e. substantially parallel to the platform plane p. The loop 199 anchors the cord 116 via the additional pulley. In the embodiments described the drive belt is provided as a cord 116. However it will be appreciated that the drive belt can take any suitable elongate form, and may have any suitable cross section. For example the drive belt can be a web, a strip, a rope, a chain or any other suitable component.

Claims

1. A flywheel trainer comprising:a base comprising a platform for supporting a user;a rotatable body configured to rotate relative to the base, wherein the rotatable body comprises a central axle and a flywheel connected to the central axle;a drive belt having a first end arranged to be accessible to a user and a second end opposite the first end that is coupled to the central axle, wherein the drive belt is arrangeable between a retracted configuration, in which the first end of the drive belt is arranged proximal to the platform and a portion of the drive belt is wound around the central axle, and an extended configuration, in which the first end of the drive belt is arranged distal from the platform and the drive belt is unwound from the centra! axle, and wherein the drive belt is configured such that pulling the first end of the drive belt moves the drive belt from the retracted configuration to the extended configuration, thereby causing rotation of the rotatable body; anda magnet arrangement comprising a first magnet arranged on the base and a second magnet arranged on the rotatable body such that the second magnet moves in and out of alignment with the first magnet as the rotatable body rotates, wherein the first and second magnets are configured to repel each other when aligned, so as to impart a torque to the rotatable body.

2. The flywheel trainer of Claim 1, wherein the first and second magnets are arranged to align when the drive belt is in the extended configuration.

3. The flywheel trainer of Claim 1 or Claim 2, wherein the magnets are configured such that like poles of the magnets face each other when the magnets are aligned.

4. The flywheel trainer of any preceding claim, wherein the platform has an upper side for a user to stand on and an underside opposite the upper side, and wherein the first magnet is arranged on the underside of the platform.

5. The flywheel trainer of any preceding claim, wherein the second magnet is arranged on the central axle.

6. The flywheel trainer of any preceding claim, wherein the central axle has a first end arranged proximal to the platform and a second end distal to the platform, and wherein the second magnet is arranged at the first end of the central axle.

7. The flywheel trainer of any preceding claim, wherein the central axle comprises an axle body, optionally wherein the axle body is frustoconical or conical in shape.

8. The flywheel trainer of Claim 7, wherein the central axle further comprises an extension portion, and wherein the extension portion extends radially outward from the axle body to define a support on which the second magnet is arranged9. The flywheel trainer of Claim 8, wherein the support is flat and extends parallel to the platform.

10. The flywheel trainer of any of Claims 7 to 9, wherein the second end of the drive belt is coupled to the central axle at a coupling location, and wherein the coupling location is located at a narrow region of the frustoconical or conical axle body.

11. The flywheel trainer of any preceding claim, wherein the rotatable body is fully arranged under the platform.

12. The flywheel trainer of any preceding claim, wherein the central axle extends along, and is arranged to rotate around, a central axis, and wherein the central axis is transverse, and optionally orthogonal, to the platform.

13. The flywheel trainer of any preceding claim, wherein the flywheel is arranged to rotate around a flywheel rotation axis, and wherein the flywheel rotation axis is transverse, and optionally orthogonal, to the platform.

14. The flywheel trainer of Claim 13 when depending on Claim 12, wherein the centra! axis and the flywheel rotation axis are the same.

15. The flywheel trainer of any preceding claim, wherein the flywheel is flat, and optionally discshaped, and extends parallel to the platform.

16. The flywheel trainer of any preceding claim, wherein the platform comprises a drive belt aperture through which the drive belt extends to permit access to the first end of the drive belt for engagement by the user.

17. The flywheel trainer of any preceding claim, further comprising a pulley arrangement for directing movement of the drive belt in a direction transverse to the platform.

18. The flywheel trainer of Claim 17, wherein the pulley arrangement comprises a first pulley, the drive belt being arranged to run around the first pulley to guide the drive belt in a direction that is transverse to the platform.

19. The flywheel trainer of Claim 18, wherein the pulley arrangement further comprises a second pulley that guides the drive belt between the first pulley and the central axle, the secondpulley being arranged such that the central axle is arranged between the second pulley and the first pulley.

20. The flywheel trainer of any preceding claim, further comprising a handle couplable to the first end of the drive belt, wherein the handle comprises a handle enclosure for containing a first encl of the drive belt.

21. The flywheel trainer of Claim 20, wherein the handle comprises a spool about which the drive belt is windable to adjust a length of free drive belt between the handle and the central axle.

22. The flywheel trainer of Claim 21, wherein the spool is rotatable to wind the drive belt around the spool, and lockable to lock the length of free drive belt, optionally 'wherein the handle comprises an actuator mechanism configured to lock and unlock the spool to permit rotation.

23. The flywheel trainer of Claim 22, wherein the spool is located within the handle enclosure and the actuator mechanism comprises a button located on an outer surface of the handle enclosure for actuating the actuator mechanism to permit rotation of the spool.

24. The flywheel trainer of Claim 22 or Claim 23, wherein the spool is located within the handle enclosure and the actuator mechanism comprises a rotatable grip that is located on an outer surface of the handle enclosure and that is connected to the spool, and wherein the rotatable grip is configured such that when the user rotates the grip the spool rotates.

25. The flywheel trainer of any preceding claim, comprising a housing defining a housing enclosure containing the rotatable body, and wherein the platform is provided by an upper wall of the housing enclosure, optionally wherein the housing comprises a lower wall opposite the platform, and wherein the lower wall defines an opening shaped such that the flywheel disc can be removed from the central axle and the housing enclosure through said opening.

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