I have post mount TRP Spyre calipers, how can I upgrade to flat mount Ultegra calipers? are there adapters available? I've only seen adapters for flat to post.
I think there are no adapters on the market to use flat-mount calipers on a post mount fork, so your options are:
- Get a flat mount fork and Ultegra caliper you want. I actually did that, the additional price will depend on new/secondhand and no-name/open mold/brand name factors.
- Get any post mount Shimano hydraulic caliper, those are all compatible. There's no actual Ultegra post mount calipers, but prior to R8000, Shimano made a non-group, Ultegra-level ST-RS685/BR-RS785 shifters/calipers, so you might use a BR-RS785 or slightly older BR-R785 (actually an XT).