GB2260300A - Cycle with foldable frame and suspension - Google Patents

Abstract

A cycle frame comprises front and rear sub-frames 30, 32 connected by a crossbar 34 pivotally connected to the rear sub-frame, and a downtube 24 which is pivotally connected to both sub-frames 30, 32. One or more of the connections between the crossbar 34 and the downtube 24 and either of the sub-frames 30, 32 is provided by a releasable coupling to allow folding of the frame for storage or transportation. The downtube 24 may also comprise an extensible and compressible member which is pivotally connected to both sub-frames to allow variation in the relative angular disposition of the sub-frames. The member may be provided with locking means to prevent relative movement between the sub-frames. <IMAGE>

Description

CYCLES The present invention relates to cycles and more particularly, but not exclusively, to collapsible cycle frames and cycle frames incorporating suspensions.

Many people choose bicycles as a preferred mode of transport for avoiding the problems of car congested towns and cities or simply for touring the countryside. Indeed cycling, especially off-road, rough terrain cycling or "mountain biking" using all terrain bicycles, is an increasingly popular pastime.

In order to smooth the ride over rough ground, it has been previously proposed to provide bicycle frames with a suspension unit to damp relative movement between the front and rear wheels.

In both GB patent specifications No. 1,062,932 and No.

1,101,442, there is described a two-wheeled cycle having a resiliently controlled telescopic suspension system for the front wheel accommodated in the housing for a steering column and a separate resiliently controlled suspension system for the rear wheel.

Unless being ridden, bicycles are cumbersome to transport. When participating in off-road or "mountainbiking" it is often necessary to transport the bicycles by car or train to the desired terrain. In order to alleviate the problems of transporting bicycles, it has been previously proposed to make bicycles foldable.

In GB patent specification No. 1,014,579, there is described a foldable bicycle having a front sub-frame and a rear sub-frame joined by a hinge under a pedal shaft such that movement of the front sub-frame about the hinge allows the front and rear sub-frames to adopt a side by side relationship.

In U.S. patent specification No. 4,448,437, there is described a collapsible bicycle having a completely separate front frame and rear frame which are coupled together in a riding disposition and detached in a collapsed disposition.

It is an object of the invention to provide an improved collapsible cycle frame.

According to one aspect of the invention, there is provided a cycle frame foldable substantially in one plane comprising front and rear sub-frames linked by a first elongate connecting means and by a second elongate connecting means wherein the first elongate connecting means is pivotally connected at respective ends thereof to the front and rear subframes and said second elongate connecting means is connected at one end to the front sub-frame and pivotally connected at a second end to the rear sub-frame, and wherein at least one of said pivotal connections is provided by detachable means, which can be released to allow folding of the rear sub-frame by being pivoted about the other pivotal connection to the rear sub-frame.

It is another object of the present invention to provide an improved cycle frame with a single suspension means for both front and rear wheels.

According to a first aspect of the invention there is provided a cycle frame, a front sub-frame to which front wheel means may be journalled, a rear sub-frame to which rear wheel means may be journalled, a first elongate connecting means to connect said front and rear sub-frames and being pivotable in a substantially vertical plane about a point of connection to one, preferably said rear, sub-frame; and a second elongate connecting means extending between and pivotally connected to said front and rear sub-frames, and being adapted to be longitudinally extensible or contractible, the arrangement being such that relative movement in a vertical plane of either of said wheel means will cause the second connecting means to extend or contract and allow both connecting means to pivot and thereby change the relative angular disposition of said front and rear sub-frames.Preferably said extension or contraction of said second elongate connecting means is damped.

Preferably said second elongate connecting means is extensible or contractible against biassing means, the strength of which may be adjustable so as to enable the grade of ride, namely softer or firmer, to be selected. The biassing means may be a spring, such as a compression spring.

Preferably said second elongate connecting means has a locking means so that when in a locked disposition, relative movement of the front and rear sub-frames is prevented.

The invention also provides a cycle comprising a frame according to said first or second aspect and front wheel means and rear wheel means which are readily attachable to the front and rear sub-frames respectively.

According to a third aspect of the invention, there is provided a cycle frame according to said first aspect in which one of said elongate connecting means is detachably connected to said rear sub-frame to allow said frame to be folded to facilitate carrying and/or storage thereof.

A carrying handle may be provided having at least one latching portion capable of cooperating with at least one, and preferably a plurality, of said elongate connecting means, when the cycle frame is in a folded condition. The carrying handle may comprise a pair of hinged sections, which, when secured together, define a plurality of tubular apertures for receiving respective elongate connecting means of the cycle frame, when folded.

A case may be provided capable of receiving the folded cycle such that when lifted by the carrying handle the weight of the cycle is fully supported by said handle.

The carrying handle may have lateral extensions adapted to support the axles of a pair of cycle wheels at their respective extremities.

Usually the wheel means and the corresponding downtube element will be provided with quick release fittings.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made to the accompanying drawings in which: Figure 1 is a side elevation of a bicycle embodying a first aspect of the invention; Figure 1A is a sectional view of a suspension means; Figure 1B is a side elevation of the bicycle of Figure 1, showing front sub-frame movement; Figure 1C is a side elevation of a bicycle of Figure 1 showing rear sub-frame movement; Figure 2 is a side elevation of a bicycle embodying a second aspect of the invention; Figure 3 is a side elevation of a bicycle embodying a third aspect of the invention; Figure 4 is a side elevation of the frame of the bicycle of Figure 2, showing a folding sequence thereof; Figure 5 is a side elevation of the frame of the bicycle of Figure 3, showing a folding sequence thereof;; Figure 6 is a diagrammatic side elevation of a bicycle in folded disposition and stored in a carry case; Figure 7 is a diagrammatic end view of a bicycle in folded disposition and stored in a carry case; Figure 8 is a diagrammatic side elevation of a bicycle in folded disposition and stored in an alternative embodiment of the carry case; Figure 9 is a perspective view of a preferred embodiment of a carrying handle for the bicycle of Figures 2 and 3, when in a folded disposition; Figures 10A - lOC are, respectively, diagrammatic representations of a bicycle frame according to Figs. 1 - 9; and two further possible embodiments.

Referring to Figure 1 there is shown a bicycle frame 10 comprising a front sub-frame 12 to which a front wheel 14 is journalled and a rear sub-frame 16 to which a rear wheel means 18 is journalled. A crossbar element 20, an integral part of the front sub-frame 12, connects the front and rear sub-frames 12,16 and is pivotable about a point of connection 22 to the rear sub-frame 16. A downtube element 24 extends between the front and rear sub-frames 12,16 and is pivotally connected to both.

A connecting piece joins the front sub-frame 12 to the downtube 24 and comprises a substantially U-shaped collar element 50. The base of the U-shaped section 50A of the collar 50 fits around the headtube 51 of the front sub-frame 12 with the arms 52 thereof projecting beyond the headtube 51. The upper end of the downtube 24 is received between the projecting arms 52 of the collar 50 and is pivotally connected thereto by a bolt 53 secured by a nut 54. The lower end of the downtube element 24 is similarly pivotally connected to the rear subframe 16 by a U-shaped collar part 54A which embraces and is secured to the seat tube 55 of the rear sub-frame 16.

Moreover, the rear end of the crossbar 20 is similarly pivotally connected to the upper end of the seat tube 55 by means of a U-shaped collar 56 which embraces and is fixed to the seat tube 55. At least of the aforesaid pivotal connections are preferably provided by detachable means, as described below with reference to Figure 2 (reference 61), to facilitate folding of the cycle frame for storage.

The downtube element 24 is longitudinally extensible against a biassing means in the form of a compression spring 29 as described below with reference to Fig. 1A. In this way, the arrangement of the crossbar and downtube element 20 and 24 respectively and the front and rear sub-frames 12 and 16 respectively is such that relative movement in a vertical plane of either the front wheel 14 or the rear wheel 18 causes the downtube element 24 to extend and allows the crossbar element 20 to pivot and thereby change the relative angular disposition of the front and rear sub-frames 12 and 16, as illustrated in Figures 1B and 1C respectively.

Referring to Figure 1A, the downtube element 24 comprises a cylinder 27 housing a piston rod 25 and being controlled by a pneumatically damped compression spring 29. An upper spring seat 31 is attached to a first end 33 of the piston rod 25, and is capable of a degree of movement within the cylinder 27 between limiting stops. A second end 35 of the piston rod is secured to an angle bracket 37A which is pivotally attached at 37 to the rear sub-fame 16 by a bolt 53. The piston rod 25 has an outer sleeve 39 which forms part of an adjustment mechanism.

The exterior surface of sleeve 39 is screw threaded and is capable of cooperating with a first end of a housing 41 arranged at one end of the cylinder 27. A lower spring seat 45 is attached to a first end of sleeve 39 and a knurled thumbwheel 47 is attached to a second end of the sleeve 39.

Rotation of the thumbwheel 47 clockwise causes the lower spring seat 45 to compress the spring giving a resultant "firmer" setting. Rotation of the thumbwheel 47 anti-clockwise causes the lower spring seat 45 to travel in the opposite direction reducing spring compression giving a resultant "softer" ride.

A locking device 120 is provided for locking the piston and cylinder assembly 25,27, when the bicycle is to be used on a highway. The locking device comprises a knurled collar 121 rotatably mounted around the cylinder 27. At the position of the collar 121, the cylinder 27 is formed with an aperture in its wall in which a locking pin 122 is located and is spring loaded in the radially outward direction into engagement with a cam surface 123 formed on the inner periphery of the collar 121. The cam surface 123 includes a recess 124, the depth (in the radial direction) of which increases progressively from one circumferential end thereof to the opposite circumferential end. The deeper end of the recess terminates in a radially extending abutment surface 125.When the collar 121 is rotated to a position in which the pin 122 is located in the recess 124 at the deeper end thereof against the abutment surface 125, it does not project inwardly of the cylinder 27 so that the suspension system becomes operative. However, when the collar 121 is rotated to a position in which the pin 122 is forced, by the camming surface 123, to project into the cylinder 27, it engages into a detent in the piston thereby to lock the suspension system.

Referring to Figure 2, there is shown a bicycle frame 28 comprising a front sub-frame 30 and a rear sub-frame 32 which are linked by a crossbar element 34 and by a downtube element 36. The downtube element 36 is pivotally connected at a first end 38 thereof to the front sub-frame 30 in the same manner to that of the frame of Figure 1 and detachably connected at a second end 40 thereof to the rear sub-frame 32.

In order to detachably connect the downtube 36 to the rear sub-frame 32, there is provided a pip-pin and lanyard arrangement 61, in place of the fixed pivotal connection of the frame of Figure 1. Proprietary pip-pins such as single acting, positive locking pip-pins and lanyards from LOCKWELL PRODUCTS Cho., may be used. The pip-pin 61 comprises a shank portion provided at its free, lower end, with ball-shaped projections 110 in the wall thereof. The shank is hollow and has a control spigot 111 slidably located therein. The spigot 111 projects beyond the head of the pin. The spigot 111 controls an internal mechanism which maintains the balls 110 in their outwardly projecting positions to lock the pin in positions or allows them to move within the shank for withdrawal of the pin. Sequential axial depressions of the spigot effect locking and unlocking of the pin.A lanyard 112 connects the pin 61A to the bicycle frame.

When assembling the bicycle for use, the pin is inserted as illustrated in Fig. 2 thus fixing the downtube 36 to the rear sub-frame 32. When disassembling the bicycle, the pippin is removed allowing the folding action to start.

Thus, the downtube element 36 is movable between a securing disposition shown in Figure 2 and a folding disposition shown in Figure 4, in which it is detached from the rear sub-frame 32. The crossbar element 34 is rigidly connected at one end 42 to the front sub-frame 30 and pivotally connected at a second end 44 to the rear sub-frame 32, in a similar fashion to that of the frame of Figure 1.

Figure 3 shows a collapsible cycle frame 46 generally similar to the frame shown in Figure 2 except that the downtube 36 is replaced by a downtube 24 incorporating a suspension system, as illustrated in Figure 1A.

In use of a bicycle as shown in Figure 1 or Figure 3, when either wheel meets a change in terrain profile, the piston rod 25 extends compressing the spring 29 until the spring pressure balances the force created, as illustrated in Figures 1B and 1C. The potential energy stored-in the spring is then released to return the piston rod towards its equilibrium position under pneumatic damping, when more level terrain is encountered.

Thus when the bicycle is loaded and moving, when either wheel encounters a bump or dip, it will cause the pivot point of the sub-frame in which it is located to move relative to the other sub-frame around the common axis. Whichever wheel 14,18 encounters the bump or dip, the pivotal movement will be away from the other wheel, causing the downtube 24 to extend in length and the spring compression to increase. Since movement of each sub-frame is independent, each wheel can adjust to the terrain it is meeting regardless of what change the other wheel is encountering. The suspension unit will damp out any large variations between the two wheels.

In use of the bicycle shown in Figure 2 the crossbar element 34 and the downtube element 36 initially occupy the securing disposition. For folding the cycle, the saddle (not shbwn), the front wheel 14 and the rear wheel 18 are first removed. The second end 40 of downtube 36 is then detached from the rear sub-frame 32 and is rotated through its arc of movement to attain the position shown in Figure 4. The rear sub-frame 32 is then rotated forward and upwards whereafter the downtube 36 is rotated back to locate between the spaced pairs of rear stays 32A of the rear sub-frame 32 in its folded position. The cycle frame 28 is then in the folded disposition. As illustrated in Figure 5, the bicycle of Figure 3 is folded in a similar fashion.The folded disposition is illustrated in Figs. 6 - 8, wherein the crossbar 34, the seat tube 55 and the downtube 24 are disposed in a vertical side by side relationship.

In order to store the folded cycle a carrying handle 48 (shown in Fig. 9) is attached to the downtube 24, the seat tube 55 and the crossbar 34. The handle bars are rotated into the same plane as the crossbar 34, the wheels are positioned on either side of the carrying handle 48 and the entire folded unit is inserted into a transport case 60 as shown in Figures 6 and 7.

The carrying handle 48 comprises a two-part plastic moulding 61A,61B, as shown in Figure 9. The parts 61A,61B are hinged together at their upper ends where they are formed with cooperating knuckle joint formations 62A,62B connected internally by a pivot pin. The parts 61A,61B have cooperating generally planar sections 63 formed with three superimposed semi-circular portions 64,65,66 which cooperate with one another, respectively, to form, when the mould parts 61A,61B are in their closed position, three superimposed tubular sections for receiving the crossbar 34 the seat tube 55 and the downtube 24, respectively, as illustrated in Figures 6 and 7, so that the folded bicycle is supported entirely by the carrying handle 48.

The mould parts 61A,61B have lateral wing extensions 67 formed at their extremities with a slotted wall 68 on which the wheels 14,18 are hung by their axles. The hinged mould parts are carried by a webbing strap 70 which is passed through upstanding hoop sections 71,72 provided on the knuckle joints 62A,62B. The mould parts 61A,61B are held together in their closed position, by any suitable quick release fasteners (not shown).

The bicycle, when folded and supported on the carrying handle 48, as described above, is inserted into the transport case 60, which is of the form of a generally rectangular box having a sloping top wall 60A. A support packing 80 is disposed at the bottom of the case 60 and has an arcuate upper surface on which lower sections of the wheels 14,18 are seated. An upper packing 81 is inserted on top of the folded bicycle and has an arcuate lower surface which rests on upper sections of the wheels 14,18 as illustrated in Figure 6. The webbing strap 70 projects through the upper packing 81 and the sloping top wall 60A of the case 60. The upper and lower packings 80,81 are connected by strip-like side members 82, integral parts of the case 60, which engage with the wheel axles.

Figure 8 shows another form of carrying bag 90 for the folded bicycle of Figure 3. The bag 90 is made of any suitable, durable material which, when not in use, could be folded and stowed, for example, under the saddle 92. The bag 90, which has a carrying webbing handle 93, allows the bicycle to be readily collapsed and inserted into the bag to enable the folded bicycle to be carried into shops, etc., for security at any rest point on a journey. In this case the saddle 92 is not removed. The bag 90, or the transportation case 60 and associated carrying handle 48, can be selected as required.

A collapsible bicycle as shown in Figure 2 may be folded and stored in exactly the same manner.

The bicycle frames, described above, may be constructed from tubular metal, plastics materials or carbon fibre.

Figure 10A illustrates diagrammatically the pivotal connections A,B,C of the bicycle frames described above with reference to Figures 1 - 9. Figures 10B and lOC illustrate possible alternative positions for the pivotal connections, A,B,C' and A',B',C" respectively. In the arrangement shown in Figure 10B, the suspension will normally act only in respect of the front sub-frame. In the arrangement shown in Figure lOC, the suspension will be provided in crossbar 20' which will be adapted to contact longitudinally when relative angular movements of the front and rear sub-frames take place.

The pivot connection C" could be made a detachable connection in order to allow folding of the bicycle frame to take place.

Claims (16)

CLAIMS:

1. A cycle frame foldable substantially in one plane comprising a front sub-frame to which front wheel means may be journalled, a rear sub-frame to which rear wheel means may be journalled, a first elongate connecting means connected at one end to the front sub-frame and pivotally connected at a second end to the rear sub-frame, and a second elongate connecting means pivotally connected at respective ends thereof to the front and rear sub-frames, and wherein one or more of the pivotal connections are provided by detachable means, which can be released to allow folding of the cycle frame by being pivoted about the other pivotal connections.

2. A cycle frame according to Claim 1 wherein said second elongate connecting means is adapted to be longitudinally extensible or contractible, the arrangement being such that relative movement in a vertical plane of either of said wheel means will cause the second elongate connecting means to extend or contract and allow both connecting means to pivot and thereby change the relative angular disposition of said front and rear sub-frames.

3. A cycle frame according to Claim 1 or Claim 2 wherein the pivotal connection between the second elongate connecting means and the rear sub-frame is provided by detachable means.

4. A cycle frame according to Claim 2 or Claims 2 and 3 wherein said extension or contraction of said second elongate connecting means is damped.

5. A cycle frame according to Claim 2, or Claims 2 and 3, or Claim 4 wherein said second elongate connecting means is extensible or contractible against biassing means.

6. A cycle frame according to Claim 5 including means to adjust the strength of said biassing means to enable the grade of ride to be selected.

7. A cycle frame according to Claim 5 or Claim 6 wherein said biassing means is a spring.

8. A cycle frame according to any preceding Claim wherein said second elongate connecting means has a locking means which can be actuated to prevent relative movement of the front and rear sub-frames.

9. A cycle frame according to Claim 8 wherein said second elongate connecting means comprise a piston and cylinder arrangement and said locking means include a locking pin movable mounted on the cylinder between positions in which it engages and locks with the piston and in which it is clear of the piston.

10. A cycle frame according to any one of Claims 1 to 9 including a detachable carrying handle having at least one latching portion capable of cooperating with at least one of said elongate connecting means, when the cycle frame is in a folded condition.

11. A cycle frame according to Claim 10 wherein the carrying handle comprises a pair of hinged sections, which, when secured together, define a plurality of tubular apertures for receiving respective elongate connecting means of the cycle frame, when folded.

12. A cycle frame according to Claim 10 or Claim 11 further including a case capable of receiving the folded cycle such that when lifted by the carrying handle the weight of the cycle is fully supported by said handle.

13. A cycle frame according to any one of Claims 10 to 12 wherein the carrying handle has lateral extensions adapted to support the axles of a pair of cycle wheels at their respective extremities.

14. A cycle frame according to any preceding Claim including front wheel means and rear wheel means which are readily attachable to the front and rear sub-frames respectively.

15. A cycle frame according to Claim 14 wherein said wheel means and corresponding sub-frames are connected by quickrelease fittings.

16. A cycle frame substantially as hereinbefore described with reference to Figs. 1, 1A, 1B and 1C, or Figs 2 and 4, or Figs 3 and 5, or any one of Figs 1, 2 and 3 together with Figs 6 and 7 or Fig 8 or Fig 9, or any one of Figs 10A, 10B and 10C of the accompanying drawings.