A gear chart that shows every gear as a colored cell on a chainring × cassette grid. Click a cell to highlight it. The orange-outlined cells are your "sweet zone" — the gears you'll spend 80% of your riding in, based on a typical cadence range.
Numbers in cells are speed (km/h) at 80 rpm. sweet zone = 22-32 km/h at 75-95 rpm, where most riding happens.
Highest ÷ lowest gear ratio
Biggest percentage gap between adjacent gears
Best gear for 30 km/h at 85 rpm
Gear charts in print usually list ratios and leave you to do the mental math. A grid of speed-at-cadence makes two questions easy — "what gear do I need to climb this at 75 rpm?" and "what cadence do I need at 50 km/h in this gear?" Both answers are right there.
The second thing this view reveals is the jumps. A wide-range cassette looks great on paper, but real life is that the 21 → 24 cog is often a 14% jump, while a 24 → 27 is a 12% jump. Looking at where the jumps cluster tells you whether your shifting is going to feel smooth or "stepped".
Tire outside diameter varies by brand, model, and pressure. We've used 700c + tire width as a stand-in. If your bike is on 650b wheels or your tires are unusually wide/narrow, expect a 1-2% difference.
It's the equivalent diameter of a penny-farthing wheel with the same ratio. Useful for comparing across wheel sizes: higher = harder gear. Modern bikes usually run 20-110 gear inches.
Yes — type any comma-separated list of teeth into the cassette field. Up to 14 cogs is fine; beyond that the grid gets crowded.
Because most riders use the small ring for climbing and the big ring for cruising. The middle (if you have one) is for transitions. The sweet zone is typically the outer chainring at moderate cogs.
This calculator was built to answer a question most online versions skip or oversimplify. It runs entirely in your browser; no inputs are stored or transmitted. The math is grounded in standard cycling physics and physiology models, and is suitable for hobbyist and intermediate training use. It is not a substitute for a coach, sports scientist, or professional bike-fit service.
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Children under 13 are not the intended audience.
This calculator is provided for general informational and educational purposes only. It is not medical, mechanical, or legal advice. Predicted values depend on inputs you supply and simplified physical models; real-world outcomes vary. Use at your own risk. Brand names are descriptive only and do not imply affiliation.