-
Yeah, I've just done some quick internet research and it sounds like the pistons on UR300 are resin rather than ceramic.
On this bike I actually have 160mm rotors on there front and back already despite it being road. I decided to increase from 140mm last year because I use it to drop my kid at nursery and on the way home we come down a very steep and twisty descent where I'm not gonna be bombing it down the same way I would it if were just me on the bike and I've got the extra weight of a hamax carress and a 2yr old on the back. I currently use the adapters front and rear to space out the existing calipers to 160mm.
I read that the UR300 are to be used with resin pads only. Is that correct? I'd thought that it was the disc that would dictate only being allowed to use resin, rather than the caliper, but I am clearly not incredibly knowledgeable on the subject.
Other considerations are that I'd need to change pads. Obviously a new caliper comes with the pads included. If I keep the current front caliper and only change the rear, then I'll have 1 type of pad on the rear and a different type on the front. That's okay, but I think in the long run I'd ideally also change the front to the same caliper. It's probably just a matter of time before that one goes.
Questions I have:
- Front and rear callipers are not interchangeable, right? I think I've answered my own question looking at the images online - they look very different.
- Are you sure my levers (RS505) are compatible with the UR300 calipers? Looking at Shimano's compatibility chart they aren't listed, but I think that's only because they are listed as different categories (road/gravel versus MTB/urban) and Shimano just isn't expecting people to want to mix and match.
- Are my existing hoses and barbs definitely compatible? Shimano lists the SM-BH59-JK-SS separately for road and MTB for some reason, and says that UR300 are only compatible with MTB, but I can't tell why or how that would be different.
- If I choose to re-use the existing hoses and barbs, what warning signs should I look for that it's not worked and I need to replace the barb? Presumably just leaking around where the hose connects to the caliper?
You are right that the UR300 is cheap as chips. I could get both front and rear from Ribble (including lever, hose, and pads) for £35 delivered, which is far cheaper than any of the other single calipers from the 105 or ultegra that I can find for sale online. Depending on answers to the above questions, I'll probably just order up both a front and rear.
- Front and rear callipers are not interchangeable, right? I think I've answered my own question looking at the images online - they look very different.
hazzelfrazzel-
I’ve just gone UR300 on my Sequoia flat bar conversion using the existing hoses. They screwed straight on without a problem. If I go back to drops I’ll just screw them on the RS505 levers. The discs that came with them have “resin only” stamped on them, but I’m sure you can use whatever you want with your road discs.
Chaley
It's usually the ceramic pistons that go rather than the seals. Mostly pushing them back in at a wonky angle, but they're quite fragile and can just break. I'd guess the UR300 doesn't use them so you'll not need to worry about that, just be wary of the front caliper having it's adapter built in so front only for whatever the fork is set to rotorwise (probably 160) cheap AF though.