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🚴 Bike Gear, Cadence & Speed Calculator

🚴 Bike Gear, Cadence & Speed Calculator

Works out what every gear on your bike actually does — how far one pedal turn takes you, what speed you will be doing at a given cadence, and which gears are duplicates you never need. The thing most riders discover is that their lowest gear is not nearly as low as they think.

Gear inches = (chainring ÷ cog) × wheel diameter. It is the diameter of the wheel a penny-farthing would need to match your gear — still the clearest way to compare one bike with another.
Reading the numbers

Gear inches is the old measure, and still the easiest to compare across bikes. Development is how many metres one turn of the cranks moves you, which is what your legs actually feel. Gain ratio divides the wheel radius by the crank length: below about 2.0 a gear is easy enough to climb almost anything on, above 4.0 it is a big gear for fast flat riding.

Two gears within about 3% of each other are effectively the same gear — you shift between them and nothing happens. Most double chainring setups have several of these, and knowing which ones means you stop hunting for a gear that does not exist.

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