Bike Gear Calculator

A gear ratio is simply the number of teeth on the front chainring divided by the number of teeth on the rear cog. For example, a 50-tooth chainring paired with a 25-tooth cog gives a gear ratio of 2.0, meaning the rear wheel rotates twice for every full pedal revolution. Higher ratios mean harder pedalling but faster speeds.

Gear inches is a traditional measure that expresses a gear's mechanical advantage in terms of the diameter of a directly-driven wheel (like a penny-farthing). It's calculated as (chainring ÷ cog) × wheel diameter in inches. Higher gear inches = harder, faster gear. It's a popular way to compare gearing across different wheel sizes and drivetrains.

Meters of development (also called rollout) tells you how far your bike travels forward with one complete pedal revolution. It's calculated as (chainring ÷ cog) × wheel circumference in metres. It's especially useful for time trialists and track cyclists who want to know exactly how far each pedal stroke propels them.

The gain ratio, developed by Sheldon Brown, divides the distance the bike travels per pedal stroke by the distance the pedal travels in that same stroke. It accounts for crank length, making it a truer comparison across bikes with different crank sizes. A gain ratio above 3 is typically considered a high (hard) gear, while below 2 is a low (easy) gear.

Most modern road bikes use 700C (622mm rim). Mountain bikes typically use 29", 27.5" (650B), or 26" wheels depending on the model. BMX bikes commonly use 20" wheels. The tyre width also affects the effective rolling diameter — a wider tyre makes the wheel slightly larger overall, increasing the meters per pedal stroke slightly.

Cross-chaining occurs when you use the largest chainring with the largest cog, or the smallest chainring with the smallest cog. This puts the chain at a severe angle, increasing wear on the chain, chainrings, and cassette. It's best to stick to combinations where the chain runs roughly straight between the front and rear sprockets.

A standard 2x11 road groupset (2 chainrings × 11-speed cassette) gives 22 theoretical combinations, though in practice several of these overlap in ratio and some cross-chain combinations should be avoided. An 11-speed 1x setup gives 11 unique combinations. This calculator shows all your valid combos in the table below the results.

Most cycling coaches recommend a cadence of 80–100 RPM for road cycling as a healthy balance between muscular effort and cardiovascular load. Professional road cyclists often spin at 90–110 RPM on flat terrain. Beginners tend to pedal at lower cadences (60–75 RPM), which places more stress on the knees over long rides.