Tag: diameter

Campagnolo has come up with another new chainring bolt pattern (why?) and we have added it to our coverage. It’s the most complete you’ll find anywhere. Print out the template that corresponds to the kind of bolt pattern of your chainring, lay the chainring down on it and you get an instant readout of the bolt-circle diameter, brand and model of the original manufacturer’s version of this chainring. We cover classic brands as well as the newest and most confusing models with irregular bolt-circle patterns. Our coal here as with all of our cribsheets is to help you match parts, and to show cross-brand compatibility when it is not obvious and not promoted by the manufacturers. Thanks to Jacob Allen for the drawings in AutoCad!

A few months ago, a reader prompted us to make some updates to our chainwheel bolt circle cribsheet. But now we have followed up on that effort, greatly expanding our coverage, and we have added a set of templates which allow you quickly to identify the bolt circle of alnost every model of chainring, and the tooth count, without the need to measure or count by hand. It’s all here: https://sheldonbrown.com/cribsheet-bcd.html. Example template is at the right.

If you can correct any inaccurate information or you can identify a chainring that we do not cover, please let us know. We are not too proud to take corrections, and we’ll even credit you on the site for your contribution!

We have reviewed the bolt circle diameter cribsheet, checked bolt-hole spacings using trigonometry and made some corrections. Apparently, the spacings were measured rather than calculated based on angles — and measurement is never exact! We have also added entries for several new patterns. Some of the new ones with uneven spacings had to be reverse-engineered from photos and, though we think that we have them right, we welcome feedback.