Bicycle Frame Geometry Designer

Enter frame numbers. Get an accurate 2D outline and every derived measurement, live.

What it does

VeloDatum is a parametric geometry model, not a general CAD package. The frame topology is fixed, which is exactly why it stays fast and accurate. You drive it with the numbers builders actually publish, and it solves the rest.

• Scaled 2D side profile with real tube diameters, wheels, fork, seatpost, saddle, stem and bars
• Stack, reach, trail, wheelbase, front center, BB height, standover, toe clearance, saddle setback and bar drop
• Toe overlap modelled in 3D: the front wheel is turned about the real steering axis and the shoe sole is checked against the tire across a steering sweep, reporting minimum clearance, the steering angle at first contact and whether the toe actually strikes
• Toe overlap is optional and off by default. Geometry never depends on it: tick Calculate toe overlap to run the model, untick it and every other metric is unaffected
• Geometry Optimizer: state targets, allowed ranges and fixed values, and a deterministic search returns ranked geometry that satisfies them, showing how closely each goal was met and what was given up. It uses the same solver and validation as everything else, and never changes your frame until you press Apply
• Classic geometry or modern stack and reach, converted both ways
• Seat tube length or top tube slope, converted both ways
• Presets for wheel sizes, tubesets, bars and complete bikes
• Save a named project to JSON, reload it later, export SVG or print a spec sheet

How to use it

• Pick your input conventions with the two mode switches at the top of the panel.
• Load a preset as a starting point, then edit. Everything updates as you type.
• Amber tiles are values the solver derived rather than values you entered.
• Name your project and hit Save to get a JSON file. Load brings it back exactly.