Yeah that's tight! For reference a Shimano wouldn't work on my setup but a Sram did. Terrible pic but below shows a 30c g-one on Kinlin rim, there's probably 2-3mm clearance all round on a shortish A-C length fork. Essentially the inside of the caliper runs flush with the inner surfaces of the fork so if the wheel will spin without a caliper it should/might work with a Rival caliper.
You could put something in the dropout to give you 2mm more of crown clearance. Of course this could be terrible advice, but may work if done right (and the dropout have enough room to do it safely)
Cheers but the point of the photo was just to highlight the difference in caliper profiles. As you can see the bike gets ridden in crappy weather and that tight clearance has never been an issue for me!
Yeah that's tight! For reference a Shimano wouldn't work on my setup but a Sram did. Terrible pic but below shows a 30c g-one on Kinlin rim, there's probably 2-3mm clearance all round on a shortish A-C length fork. Essentially the inside of the caliper runs flush with the inner surfaces of the fork so if the wheel will spin without a caliper it should/might work with a Rival caliper.
I'd stick with the 25c and DA caliper.