This invention relates to apparatus for and a method of deterring rotation of, in particular, a pedal cycle erank relative to a frame of the cycle, when the drive thereof is removed.

It is known from, for example, DE 152332(A) DE595973 (A) and WO2009136801 (A1) to lock a bicycle crank releasably in a condition fixed against rotation relative to the frame, or, from DE 19850712(A!), to lock a pedal releasably in a condition fixed against rotation relative to a crank. Such provisions are made for various reasons.

When a cyclist, particularly a BMX (bicycle motocross) cyclist, is performing a trick that requires him to take his feet off the pedals, the crank tends to continue to rotate under its own momentum (plus, of course, that of the pedals) so that, when the rider comes to put his feet back on the pedals, the pedals are in different positions about the crank axis compared to where they last were. This can cause the rider to misplace his footing and as a result fall from the cycle.

There is disclosed in GB2458217 (A) a bicycle which has a frame, with a head tube and a bottom bracket shell, and a fork with a fork shaft. A bearing is provided for the fork shaft in the head tube, and a bottom bracket is provided for bearing a crank shaft in the bottom bracket shell, the crank shaft having crank arms carrying pedals, wherein the bottom bracket and/or the bearing for the fork shaft comprises at least one bush bearing, instead of the conventional ball bearing. It is stated that, because of the use of at least one bush bearing, friction between the bottom bracket and the crank shaft occurs, which makes it easier to perform tricks on a BMX freestyle bicycle.

According to the one aspect of the present invention, there is provided apparatus for deterring rotation of a foot-drivable first part of a pedal cycle when the drive is removed from said first part, said apparatus comprising a member insertable between a first portion fixed relative to said first part and a second portion fixed relative to a second part of said cycle, and, while so inserted, displaceable between an ineffective condition in which said member does not substantially brake said first part and an effective condition in which said member substantially brakes said first part, and a device which serves to displace said member between its ineffective and effective conditions.

According to another aspect of the present invention, there is provided a pedal cycle including first and second parts which are respectively a crank and a frame rotatably mounting the crank, and an apparatus for deterring rotation of said first part relative to said second part when drive is removed from said first part, said apparatus comprising a member inserted between a first portion fixed relative to said first part and a second portion fixed relative to said second part and dispiaceab!e between an ineffective condition in which said member does not substantially brake said first part and an effective condition in which said member substantially brakes said first part, and a device which serves to displace said member between its ineffective and effective conditions.

According to a further aspect of the present invention, there is provided a method comprising displacing a member between:-

(i) an ineffective condition in which said member does not substantially brake rotation of a first part of a pedal cycle relative to a second part of said cycle, said first part and said second part being respectively a crank and a frame upon which said crank is rotatably mounted, and

(ii) an effective condition in which said member substantially brakes rotation of said first part relative to said second part.

Owing to the invention, it is possible for a rider to change the braking effort on, in particular, a crank to suit circumstances. For example, a BMX rider cycling from home to a BMX competition can set the device such that there is no significant braking effect and then, when required to perform tricks, can set the device such that the crank is braked, but not fixed against rotation relative to the frame.

Advantageously, in the effective condition of the member, the degree of effectiveness is adjustable. For example, an inexpert BMX rider may wish to have heavy braking of the crank to ensure that the crank remains almost where his feet left them, whereas an expert may choose to allow more freedom for the crank. Moreover, such adjustability allows for take-up of frictional wear.

The member preferably comprises a resilient washer having an outer peripheral portion thinner than an inner peripheral portion thereof, with the latter portion being for abutting only an inner shell of a rotary bearing between the crank and the frame, while the outer peripheral portion is spaced from an outer shell of the bearing and not contacting the inner shell but pressable by the device against the outer shell to provide the braking effect.

The device may comprise one or more set screws carried by one of the crank and the frame to which the member is fixable, with adjustment of the device being from the region of the device itself.

It will be generally understood that, owing to this invention, it is possible to add resistance to a crank bearing so that, when the rider is not turning the crank, it stays in the same position, or almost the same position, about the turning axis where the rider left it.

In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which:-

Figure 1 is a diagrammatic, fragmentary, underneath plan view of a bottom bracket region of a BMX cycle; and

Figure 2 is a diagrammatic, fragmentary, vertical, axial section through part of the region.

Referring to the drawings, the bicycle includes a frame 2, a crank 3 comprising a drive arm 4, a non-drive arm 6, and an axle 8. Fixed to the arm 4 by way of a bolt 9 is a chain drive sprocket 10 adjacent a bearing cover 12. Towards the opposite end of the axle 8 is another bearing cover 4 protecting a bearing 16 (in this example a ball bearing) having inner and outer shells (in this example races) 18 and 20 and, in this example, balls 22. Between the cover 14 and the bearing 16 is a resilient, plastics, drag washer 24 encircling the axle 8 and having a thicker inner peripheral portion 24a clamped between the cover 14 and the inner race 18 and a thinner outer peripheral portion 24b spaced axially from the outer race 20. Clamped between the cover 14 and the arm 6 is a spacer 26. Mounted in the cover 14 are a plurality of, in this example three, equiangularly spaced grub screws 28 which can be screwed in to press the portion 24b adjustably against the outer race 20 (so as to apply an adjustable drag against turning of the crank 3) and screwed out to remove the pressure from the portion 24b (so that the portion 24b is able to move resilientiy out of contact with the outer race 20). Thereby, the resistance can be added and removed easily without the rider's having to remove parts from the cycle or put any significant extra pressure on any of the moving parts of the cycle, which might cause them to fail.

The screws 28 can be tightened sufficientl to stop the crank 3 from turning when the feet are removed. The amount of resistance can be altered to suit each rider's preference by fine adjustment of the screws 28. If the rider does not want the resistance, then the pressure can be removed and the crank 3 will rotate in a conventional manner. The cover 14, the washer 24 and the screws 28 are preferably designed to fit at least most types of sealed cartridge bearing bottom brackets, particularly USA, Mid, Spanish and Euro, which are the four main bottom bracket sizes used in the pedal cycle industry.