Mechanics. Designating an enclosed two-speed epicyclic gear originally designed for use on bicycles. Cf. crypto, adj. Now historical and rare.

= crypto-dynamic, n. Obsolete.

a combination of a three-speed gear with a ‘coaster’ brake on a cycle.

A bicycle gear in which the ratio is changed by switching the line of the chain (while pedalling) so that it jumps to a different sprocket on the…