Bike Forums - View Single Post - Gear inch question

10-03-20, 07:10 PM

#43

79pmooney

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Quote:

Originally Posted by trailangel

I actually do this..... I know what gear inch I am riding at any time. It's always been a way for me to calculate mph while riding. Never had a speedometer and don't use strava or a gramin or any electronic device. I usually ride in a certain gear inch per various roads, and it's easy to spin 90 rpm on the crank because that is one second of time per 1.5 revolution per crank.

+1 I always liked that 100 RPM in 67 gi is 20 mph. (67 gi - 42 X 17, a very common fix gear ratio.) Easy to go from there and calculate all sorts of stuff in my head while riding. 100 RPM - 10 pedal revs n 6 seconds. Useful back when we wore watches.

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