Bike Gear Ratio's Explained
|
| Gear Ratio |
Sample Calculation |
| chain ring size / rear cog size e.g. 52 / 11 |
Gear Ratio = 52 / 11 = 4.73 |
Gear Size
i.e. equivalent wheel diameter on a penny-farthing
Gear size = gear ratio x wheel diameter e.g. 690 mm |
Gear Size = 4.73 x 0.69 = 3.26 m |
Distance travelled for one revolution of pedals
Distance = gear size x pi |
Distance per pedal rev = 3.26 x pi = 10.24 m |
Speed at a given pedal speed
e.g. cadence 80 rpm
Speed (m/s) = Distance per rev. x C /60
Speed (mph) = speed (m/s) x 2.237 |
Speed = 10.24 x 80/60 x 2.237 = 30.55 mph |
Important Observations:
If you can turn the pedal's twice as quickly you go twice as fast!
If you get a smaller cog on the back wheel you can go faster
If you get a larger cog on the front chain set you can travel faster
Bigger wheels would help
If you measure speed in kilometers per hour you appear to be travelling
faster
Why not download the spreadsheet for
these calculations
All
formulae courtesy of official team statistician
(retired)
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