: Common on older American-made bikes and children's BMX bikes. A single piece of forged steel forms both arms and the axle.
In internal combustion engines, the crankshaft is the "backbone" that converts linear piston motion into rotary motion to drive the wheels. CrankHD
: In this design, the spindle is permanently attached to one of the crank arms (usually the drive side), simplifying installation and increasing stiffness. Engine Crankshafts : Common on older American-made bikes and children's