If using cps washers they go above and below the caliper as stated.

I know there’s a difference front to rear in adaptor capacity – what does 20 on one end is 40 on the other but don’t remember which way round.

I can post pics of my Elixir R’s if it helps but I think we’ve covered everything…

Just looked through the order from merlin and it’s described as

1 x Avid Caliper Mounting Brackets 200mm Post Front or 180mm Post Rear

so you can forgive me for purchasing it!

http://www.merlincycles.com/avid-caliper-mounting-brackets-55672.html

Dave, it just didn’t line up to the rotor properly. IIRC the caliper cleared the adapter but just didn’t meet the disc. Compared to the actual Avid one the superstar one was massively more angled. Works absolutely fine on another shimano brake that’s 160>180. I couldn’t work it out cos it’s supposed to be a standardised system???

Proper 20mm avid one I just got sits like this (although this one is 180mm frame > 200mm disc it’s the same for 160>180:

Ah. Is the spacing on the new Trails different from the older Elixirs as far as adaptor fit is concerned?

I know I’ve read one of the new Sram/avid types doesn’t use cps any more, but it would make sense if the adaptors for such spaced an extra 10mm or so unless the difference was built into the caliper body…

If that’s the case an adaptor that was fine for Elixirs with 200mm rotors might only cover an 180mm with trails, which seems to be where you are?

Just a guess…