Cycling
Bike Size Calculator
Get a starting frame-size range from your inseam for road or mountain bikes. A heuristic, not a fit.
Free · instant · no sign-upDeterministic
Result
Suggested road frame54–56cm
Heuristic starting range only — stack/reach and fit matter more than frame size; get a bike fit.
The formula
Inseam heuristic
road frame(cm) ≈ inseam × 0.665; MTB frame(in) ≈ inseam × 0.226
Source: Long-standing LeMond / MTB sizing heuristics
What it means
- A quick ballpark before you shop or book a fit.
- Frame size gets you close; contact points do the rest.
Limitations
- Heuristic only — geometry differs by brand and model.
- Stack, reach and a proper bike fit matter more than a single number. Always test-ride.
Educational only
This is a deterministic tool: the same inputs always give the same result. It is for learning and planning, not a substitute for coaching or measurement.
Keep exploring
Follow the threads from this tool into the wider knowledge base.