Disc Brake Mounts

We stock plenty of disc brake mounts in all shapes and sizes to fit your brake calipers to your bike in exactly the right spot. Brake mounts can be a little tricky, with lots of different variants.
Let’s unpack some of the common considerations.

Frame-to-Caliper mounting style:
There are three common ways in which disc calipers attach to the frame: IS, Post Mount and Flat Mount.
IS mount uses two holes, facing perpendicular to the bicycle’s axis of symmetry. Virtually no disc calipers attach directly to an IS mount, however it is very common to find IS mounts on a frame as an in-between mounting point. That is, an adapter is attached to an IS mount, and the caliper is in turn attached to the adapter.

Post mount and Flat Mount both use two holes, but unlike IS mount, the holes run parallel to the bicycle’s axis of symmetry. At the rear of the bike, Post Mount holes are further apart (74mm) than Flat Mount (34mm). At the front, the spacing of the holes may be the same, but Post Mount uses an M6 bolt while Flat Mount uses M5. Post Mount is more common on mountain bikes, while Flat Mount is found more frequently on road and (increasingly) gravel bikes.

Rotor size:
Disc brake rotors come in a range of sizes, and for good braking, we need the brake caliper to bite down at the right spot on the rotor, near the outer edge. The correct disc brake mount is essential for this positioning.
Rotors are most commonly found in 140mm, 160mm, 180mm and 203mm sizes, with smaller rotors found on road-oriented bikes, and larger rotors found on more trail-oriented mountain bikes.
When selecting the disc brake mount adapter you need, you’ll need to check what your frame’s “native” rotor size is, versus what rotor you want to use, and use an adapter to bridge the distance between the two.