US Patent 7334500 Pedal crank having solid coupling

A pedal crank includes a crank arm having a hole formed in one end to receive one end of a crank shaft which may be rotatably attached to a bicycle frame. An expanding device may be engaged in the end of the crank shaft for expanding the crank shaft to engage with the crank arm, and to solidly secure the crank shaft to the crank arm. The crank arm and the crank shaft may include knurled surfaces for solidly engaged with each other. The expanding device includes a locking member engaged into the crank shaft and having an inclined outer peripheral surface for engaging with the crank shaft, and for expanding the crank shaft when the locking member is moved relative to the crank shaft.