A handy printout to work out a chainring or crank BCD if you are unsure.

Can be easier to lay the chainring over the printout.

Scroll down to the BCD Guide

For ALL things bike.

Specs, measurements, history, and more.

If it isn't here, you might not need it.

For all things Shimano, check their compatibility charts.

Every shimano part should have a part number stamped on it somewhere. Use that to search by part number on the top right.

Comparison site with many many different shapes and styles of handlebars