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Gearing & Sprockets

Gear Ratio Change Calculator

Compare an old sprocket pair to a new pair. Reports percent change, equivalent tooth moves, and how much taller or shorter the bike feels.

Inputs
Results
Live

  • Gearing change

    6.25%

    Shorter

  • Old ratio

    3.692:1

  • New ratio

    3.923:1

  • Speed factor vs old

    0.941×

  • Acceleration factor vs old

    1.063×

  • Rear teeth for same old ratio

    48T

    On a 13T front

Formula

% change = (new ratio − old ratio) / old ratio × 100

One tooth on the countershaft is worth about 3–4 teeth on the rear.

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