Chainring Tech Information

Tech Information

All PILO chainrings are CNC’d and are milled from 7075 T7351 billet aircraft grade aluminium, and finished in a hard anodized black coating for durability. PILO’s tooth geometry is highly engineered, tested with riders in the field and is the best out there, quiet in operation and does not drop chains!

The BCD (Bolt Circle Diameter) is the diameter of the circle that passes through the centre of all the bolts on your chainring, generally it is measured in millimetres.

Knowing the BCD of your crank set is essential when choosing a new chainring for your bike. In many cases, the BCD is written directly on to the chainring, as shown in the image below.

Mostly it will be stamped or engraved on the back of the chainring.

If it is not indicated on your chainring, you will need to measure it, ideally with calipers. The BCD is the distance between two opposite bolts. It can be somewhat difficult to take this measurement if you don’t have calipers, as the crank arm can get in the way. There are symmetrical and asymmetrical chainrings. The drawing to the right of the page illustrates both types of chainrings, and the table below shows the measurements corresponding to each type of BCD.

There are other types of BCD (102, 110, 120, etc.), but we do not currently offer compatible chainrings.

Chainrings can also be mounted directly to the crank too

The various interfaces are referenced below. We recommend mounting the chainrings with the original fitting bolts provided with your crank set.