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Bicycle Frame Size Calculator
x402
Bicycle Frame Size Calculator is a paid API for AI agents from bike-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-30).
Estimates bicycle frame size (seat tube in cm and S/M/L letter size) from inseam measurement and bike type, with an optional height-based letter size cross-check.
Price / call$0.02
Success—
StatusUnknown
How this service works
Rough bike frame size (seat tube cm and S/M/L) from inseam by bike type, with a height-based letter size cross-check.
Output
Returns the estimated seat tube length in cm (and inches), the nearest even cm size, adjacent sizes for comparison, the S/M/L letter size derived from inseam, an optional letter size cross-check from body height, the bike type used, and a disclaimer about the estimates being a starting point rather than a definitive fit.
Example use cases
Road bike purchase sizing
“I'm 175 cm tall with a 30-inch inseam and I want to buy a road bike — can you tell me what frame size in cm I should look for and whether that's a medium?”
Mountain bike fit for a beginner
“My inseam is 76 cm and I'm buying my first mountain bike. What frame size do I need in both cm and the S/M/L sizing?”
Gravel bike sizing cross-check
“I'm 183 cm tall with an 84 cm inseam and I'm looking at gravel bikes — what seat tube length should I target, and does my height-based letter size match?”
Technical details
Endpoint
GEThttps://bike-calc.x402tookit.com/frame-size?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a quick, formula-based starting frame size estimate from inseam and bike type, especially when the user does not yet have a specific bike in mind and wants a cm seat tube length plus letter size. It covers road, road-compact, gravel, mountain, hybrid, and city bike types. Prefer this over a full bike fitting service when no professional fit data is available and a rough estimate is sufficient.
Side effects
- Missing required inseam parameter returns a 400 error
- Inseam value outside plausible human range may return degraded or null results
- Invalid bikeType string falls back to default road calculation
- Providing height without inseam still requires inseam as it is required
- Unit mismatch (e.g. passing inches without unit=in) yields incorrect frame size
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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