I have an IS mount for the rear brake on my frame. I am in talks to buy a set of brakes, both with post mounts. Is there an adaptor to take a 160mm brake with a post mount fitting to a frame with an IS mount?

I know there is for forks, wondering if the same can be done with the rear brake on the frame. Excuse potentially silly question.

IS to Post adaptor? Yes. Try Discobrakes for cheap ones.

magura qm12 from memory?

The main question I had was whether it would work equally for post to IS on the frame as post to IS on the fork, but it seems to make no difference. Thanks.

Front and rear ones are different, you need a PM-IS R160 (in superstar’s language).