Today’s coaches corner is all about gears. Simon Tacx wanted to understand more about the variations in chain rings & gear ratios.

Firstly basic terminology:
Spider: this is the five probes which spread out from the centre of the cranks. Road bikes traditionally have five to spread the load where mountain bikes typically have four due to the smaller circumferences.
Crank length: this is the length of the pedal arm from the centre to the pedal. These came range from 160mm to 175mm. Depending on the length of your length the length of your cranks will vary.
Chain rings: these are the discs which go around the pedals which generates the momentum to cycle. See below for further information. Bigger = harder small = easier
Cranks sizes: 130 or 110. This is the circumference size of the cranks rings. 130 is standard & 110 compact. If you buy 110 chain rings they will not go onto a 130 crankset and visa versa.
Rear cassette: either 10 or 11 cogs on the rear wheel. Smaller = harder, bigger = easier. The opposite to the front chain rings
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