What is the crank?

Crank on the bike: 2 radial and arranged arms, combined with a wave that run through the bottom bracket.

Crank:
2 Radial and arms arranged opposite, combined with a wave that run through the bottom bracket. The crank system converts the pedal movement of the legs into a rotary movement of the crank. The pedals are screwed on at the outer part of the crank arms.

Relevant contributions:
Set bicycle circuit, Determine optimal frame size