Bicycle gear calculations are based on the distance, in metres, that a bicycle travels for each turn of its pedals. This distance is commonly called 'metres development' – a rather odd name for a logical and useful way of measuring gears.
Low gears will move your bike a very short way up the road for each turn of the pedals – just what you need for tackling steeper inclines at slow speed.
High gears will move you three or even four times as far – assistance from gravity or a tail wind will probably be needed!
For practical purposes, the extremes are:
- 2 metres : lowest gear
- 9 metres : highest gear
Summary: These are the distances that your bike will move forward for one revolution of the pedals.