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The gear ratio is the ratio between the number of teeth of the chain wheel
(called chain ring) and that of the rear wheel hub (rear cassette = several sprockets) The development is obtained by multiplying the gear ratio by the circumference of the wheel. The rate is between 80 and 120 Rpm On my MTB, I have: a cassette 9 speed: 11-32 3 chain ring: 22-32-44 26" tire (663mm diameter or 2.0829m circumference) this will give ... - on a flat ground: 44/11 = 4 x 2.08 = 8.32 m at 80 Rpm 8.32 * 80 * 60 = 39936 meter/h or 40 km/h at 120 Rpm 8.32 * 120 * 60 = 59904 meter/h or 60 km/h - on a large slope: 22/32 = 0.6875 x 2.08 = 1.43 m at 80 Rpm 1.43 * 80 * 60 = 6864 meter/h or 7 km/h at 120 Rpm 1.43 * 120 * 60 = 10296 meter/h or 10 km/h |
