Bicycle Gear API
Bicycle gearing maths as an API, computed locally and deterministically. The gear endpoint takes a chainring and cog tooth count and a wheel size and returns every common gearing metric: the gear ratio, gear inches (the classic measure — ratio times wheel diameter in inches), the gain ratio (Sheldon Brown's crank-length-aware measure), the development or rollout (metres travelled per crank revolution), and the road speed at a chosen cadence in km/h and mph. The speed endpoint converts between a gear-and-cadence and road speed in either direction — the speed at a cadence, or the cadence needed for a target speed. The table endpoint builds a gear chart: give one or more chainrings and a cassette of cogs and it returns a matrix of gear inches, development, gain ratio or ratio for every combination — ideal for visualising a drivetrain. Wheel size can be a preset (700x25c, 26-inch, 29er and more) or an exact rolling circumference in millimetres, and crank length is configurable for the gain ratio. Everything is computed locally and deterministically, so it is instant and private. Ideal for cycling apps and bike-fit tools, drivetrain and gear-ratio planners, and bike-shop and component sites. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is bicycle gearing; for cycling power, FTP and training zones use a cycling API.
api.oanor.com/bikegear-api
