how can you tell if a set of brakes are IS mount and a post mount? cheers

note the holes where the bolts go on the caliper
Post mount

everything else is IS

Save the picture to your computer, as this regularly confuses me 😕

This caliper is IS mount. It screws straight to the fork or frame

This one has the holes at a different angle to the one above and needs an adaptor to attach to the frame

Hope that helps 🙂

Is there a benefit of one over the other?

cheers 🙂

Rob, post mount is easier to set up, IS mount is a bit lighter (And I think looks neater)

they are interchangeable if you get the correct adaptor for the fork/frame.

so what does boxxer mount look like?

This one has the holes at a different angle to the one above and needs an adaptor to attach to the frame

unless the frame is post mount….

Boxxer mount is similar to IS I think (sideways bolted) but possibly different dimensions

Also may hopefully be helpful to add:
1. Most current brake calipers out there are post mount.
2. Post mount caliper onto post mount fork seems to be the trend/most common.
3. Post mount caliper onto IS fork is a fairly standard adaptor.
4. Most frames have IS mount at the rear and the adaptor to post mount caliper is usually included with the brakes.

Hope that helps