Every gear, the duplicates, and the one the climb needs.

The question is never "what are my gear inches". It is "will a 34×32 get me up that 8% climb at a cadence I can hold, or do I need the 36 cassette". This answers that one.

WHAT IT DOES

• Full gear chart: gear inches, development (metres per pedal turn) and gain ratio for every ring and cog
• Speed at your low and high cadence for every gear, km/h or mph
• Near-duplicate gears flagged (within 3%) so you know which to skip
• Biggest jump between neighbouring gears, with a warning above 15%
• Range as a percentage
• Two bikes side by side: range, lowest and highest gear, usable gears, average and biggest jump, climb cadence and top speed, with the winner marked on each line
• Route GPX: load the course file and it finds the steepest 300 m and steepest kilometre, the distance above 8% and 12%, draws the profile and runs the climb check on the real worst pitch
• The climb check: grade, weight and watts in. It solves the power equation (gravity, rolling resistance, air drag, drivetrain loss) for your climbing speed, converts that to cadence in your lowest gear, and if that is too slow it tells you the cog or ring that fixes it

Built in

12 common wheel and tyre sizes with measured circumferences. Any chainring and cassette. Crank length for gain ratio.

Who it's for

Road, gravel and mountain riders choosing a cassette, comparing 1× against 2×, or deciding whether the new bike's stock gearing will survive the local hills.

What you get

• The calculator (one .html file, runs in any browser, offline)
• A 1-page quick-start guide

Good to know

• One file. No install, no account, no subscription, no internet needed after download.
• Your data stays on your computer. Export a backup any time; import it on another machine.
• Works on Mac, Windows, Linux and iPad (open the file in Safari or Chrome).
• Instant download.

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