Got a new gravel grameset (Open U.P.) and swapping over the gear from my Curve onto it. The Open is flat mount, so I bought some 160mm flat mount to post mount adapters to swap over the post mount brakes I was running on the old frame (SRAM Rival Hdr).
Rear fits and works fine. But the front caliper sits out too far, so the rotor is only barely engaging with the caliper. I’d say the adapter is about 5-10mm too big.
What am I missing here? It’s the same caliper, adapter and rotor front and rear. If the adapter was wrong, why does it work fine on the rear? A 180mm won’t fit, as is it needs a 165-170mm rotor.
The only solution I can think of is to fit a 180mm disc on the front and add some longer bolts and spacers onto the adapter to move it out 10-15mm, but that’s a lot of spacers.