How to choose your brake adaptors?
It can be tricky to choose a brake adaptor. This little guide will helps you to find the correct model for attaching brake callipers to frames and forks.
There are two type of disc mounts on the market:
- The international standard or IS: to recognize this format, bolt holes need to be 51mm apart and are perpendiculare to the forks or to the frame.
- The Post Mount or PM: in this format, bolt holes are parallel to the forks or to the frame and are 74mm apart.
In many cases, frames will have International Standard Mount for attaching the rear brake calliper and forks will have PM system.
They serve two purposes:
- Offer compatibility between the two standards. For example, to install an IS calliper to an PM forks, to install a PM rear disc brake to an IS MTB frame.
- To use a larger disc rotor. E.g. to use a 180mm rotor with a forks designed for a 160mm rotor.
Most aftermarket adapters are made from Aluminium CNC machined and are compatible with different brands: Shimano, Sram, Avid, Magura, Hope... The hardware can be supplied or not, double check the product description before your buy.