Post Mount
Post Mount is the dominant brake caliper mount on mountain bikes. The caliper bolts to two threaded posts 74 mm apart (74.2 mm exactly) with M6 bolts, parallel to the rotor, at 6–8 N·m. Its big advantage: the caliper holes are slotted, so by loosening, squeezing the lever and re-tightening, the caliper self-centers over the rotor. For larger rotors you use a caliper adapter.
If your bike is a mountain bike, your brake is almost certainly Post Mount. It's robust and among the easiest to align.
What it is and how to align it
The caliper sits on two posts protruding from the frame or fork and is held by two M6 bolts. Since the caliper holes are slotted (with play), alignment is simple: loosen, pull the lever so the caliper centers itself over the rotor, and re-tighten to 6–8 N·m. The native post height defines the rotor that fits without an adapter (typically 160 or 180 mm).
Key data
What it fits
It fits any Post Mount caliper (Shimano, SRAM, Magura) and the rotor the native post height allows; for a larger one, a caliper adapter. It doesn't accept Flat Mount calipers directly (Flat→Post adapters are very restrictive).
If you don't know which mount, rotor or fluid your brake uses, send us the case. Real diagnosis, nothing to sell you. Message us on WhatsApp
Frequently asked questions
How far apart are the Post Mount posts?
74 mm center to center (74.2 mm exactly), with M6 bolts. That's what distinguishes it from Flat Mount, which is 34 mm.
How do I align a Post Mount caliper?
Loosen the two bolts, pull the lever so the caliper centers itself over the rotor, and re-tighten to 6–8 N·m. The slotted holes allow it.
Can I fit a Flat Mount caliper on Post Mount?
With an adapter, but it rarely pays off: Flat→Post adapters add a lot of height and are restrictive. The norm is Post→Post with a size adapter.