Reference Tables for Machined Bike Parts
The dimensions you cannot change, in one place. Designing a bike component means looking up the same interface numbers every time, usually across six browser tabs. These tables exist so you can stop doing that.
Free, no sign-up, no email gate. Link to them, print them, put them on the wall. If you find a mistake, tell us and we will fix it.
- Tables
Bicycle component interface standards
13 tables covering steerer and bar diameters, seatposts, bottom bracket shells, crank spindles, chainring bolt circles, chainline, hub spacing, freehub splines, brake mounts, threads, bearings and spoke holes. Sources under every table, downloadable as CSV or JSON.
- Tables
Alloys and finishes for machined bike parts
Tensile, yield, density and stiffness for the alloys that actually get machined into bike components, plus what each finish does to your dimensions.
- Checklist
RFQ and drawing checklist
What a machine shop needs before it can quote without guessing. Printable, and it works whoever you send the drawing to.
- Glossary
Bike part machining glossary
Bolt circle, chainline, wall thickness, GD&T and the rest of the vocabulary that shows up on a drawing or a quote, defined in one place.
- Calculator
Chainring BCD calculator
Measure two adjacent bolt holes and get the bolt circle diameter, or the other way round, with the chord table for every common 4, 5 and 6-bolt pattern.
- Calculator
Anodize growth calculator
What Type II or Type III anodizing does to a bore, shaft or face, the size to machine before coating and how much of your tolerance the coating alone uses.
How these are maintained
Standards change, and component makers deviate from them. These tables are checked against published standards and component maker drawings, and the date of the last check is on every page.
- Last checkedSeptember 27, 2026
- Not a substituteVerify against the component maker's own drawing before you cut metal. A table is a starting point, not a specification.
- CorrectionsEmail with the page and what is wrong. We fix it and note what changed below.
- SourcesEvery standards table names the published pages it was checked against, and the whole set is downloadable as CSV or JSON under CC BY 4.0.
Change log
What was added or corrected in the reference section, newest first. Corrections sent in by readers are logged here with what changed.
- Sources listed under every interface table. Tables published as CSV and JSON under CC BY 4.0.
- BCD calculator added, with the chord table for common patterns.
- Anodize growth calculator added for bores, shafts and faces.
- Glossary published.
- Interface standards, alloy and finish data and the RFQ checklist published.