An improved foot-actuated bicycle braking system is described. A first invention lies in a chain-side spider assembly adapted so that there is no lockup when a rider re-starts forward pedalling after braking via back pedalling. To this end, there is provided a degree of relative movement between the spider (or sprocket hub) (26) and the crank arm (25). The engagement mechanism comprises a limited movement dog clutch (51, 33) allowing limited rotational movement between spider and crank arm. The crank arm is biased by means of a spring mechanism which biases the crank arm against the hub or spider. The spring acts as a return spring and absorbs the shock when the cyclist begins forward pedalling. A second invention lies in a unidirectional roller bearing clutch mounted integrally with the axle end of the crank. The resulting component may be mounted upon a pre-existing bottom bracket axle and be connected to braking actuation means which operates front and/or rear brakes. A third invention lies in adjustable retention provided to the front and/or rear brakes by using a novel bias clamp. The bias clamp is constructed in the form of an integrated locking device having a labyrinth located therein in such a manner that, when a brake cable is threaded through the labyrinth, the brake cable biases against itself and the bias clamp thereby locks the brake cable in relation to itself. The bias clamp also provides a means of adjusting the front and rear braking forces to suit a user. The adjustment is effected by means of the specific location of the braking actuation means connection to the bias clamp. The present improved bicycle system may find application in virtually any chain-driven device, particularly off-road bicycles where hand-braking may be inadequate or uncomfortable.