I have a Hope RX4+ on the front of my gravel bike, and having very tight pad clearance it’s pretty sensitive to alignment. I’ve been putting up with a bit of a squeak for a while but having tried to fix it it’s just gotten worse and worse. I’m no newbie to setting up disc brakes but this one feels beyond me and I’m wondering what else to try.
So far I’ve cleaned and lubed the pistons, installed a brand new rotor and done my usual routine of centering the caliper with the pads in over a white background. It kind of feels like the caliper is twisting perpendicular to the fork blade. My next thought is to take it to a shop and see if it needs facing (or just a more skilled eye) but I thought I’d see if there was anything the Escape hive mind might suggest to try while I wait for an appointment.
I’ve had mixed experiences with the RX4s. I’ve had them on a gravel bike for awhile, and currently have a different set on a gravel tandem with 203 rotors. The gravel needed a lot of finesse, then ran fine for awhile. After swapping to a different frame I just could not get them rub free consistently. The tandem has been fine and hands-off, though I did go through a few bleeds and pads before identifying a bad piston seal.
I’d advise you use their 3d printed tools to advance and exercise a single piston at a time until they all advance evenly. Message me (is that a thing here?) and I’ll send you a couple. Between working every piston, ensuring a perfect bleed, and really getting the centering right you can get them working. I got sick of the song and dance on the gravel bike and just put shimano calipers on. The tandem has been great (knock on wood), but I also ride it less given the maintenance time it takes.
RX4s have a nice feel and power, but I’m not sure they’re worth it over the ease of the shimano 2 pistons. Though, you may be on SRAM?
I have mine running perfectly. Couple of things - the pistons need to be clean and coming out evenly. The rollback on the seals is very sensitive but you only need to clean with soapy water. Brake oil. As mentioned above the tools to exercise the pistons will make life easier.
Also get a disc rotor straightening tool and make sure the rotor is dead straight. Even if they anre new they can come with a little wobble. And lastly make sure the disc is running through the middle of the caliper. It’s a PITA to set them up but I have two bikes with them on with Rival E1 levers and they are amazing and worth it over the crap SRAM calipers.
Make sure the disc brake mounts on your frame are perfectly square. Often times paint or other crap from the factory means that a brand new frame right out of the box will have to be faced. I have a set of RX4 and RX4+ on two different bikes and they both were a bitch to set up. I personally use a light below the caliper to help line it up. These are some of the most finicky brakes I’ve worked on in 4 years as a bike mechanic but I think the performance is worth it
Ditto to the above things about the pistons and making sure the rotor is straight. I have a 3d printer and should still have the files somewhere on my computer if you want.
I feel your pain. Tightening the calipers should not change the rotor/pad interface unless the mounting bosses are not square and need to be faced. Unfortunately, facing tools are expensive and most home workshops don’t have them. If it’s not too bad, you can try to skew the alignment towards the side that rubs by inserting both sides of a pad/rotor alignment tool like the one here on the side that rubs. Note that if you put one spacer on either side as designed, it’s often not enough to keep the pads from rubbing once you remove the spacers. If you tighten the calipers with both spacers on one side, there’s often enough “preload” that even if it moves the caliper towards the rotor, the spacer will save enough space when it’s removed to keep it from rubbing. It’s trial and error for sure, but I absolutely hate brake rotor rub. Note you can also just use feeler gauges; I have a set of varying thicknesses that can be stacked to provide whatever thickness I feel is needed. Good luck!
Thanks for the replies everyone!
I’d already done all the sticky piston jobs, performed zen meditation in order to do a good bleed on the brakes and sacrificed my first born to the Dark Lord Båřñøłðşŵîčķ to try and sort the brake so I gave in and took it to an actual professional.
It turns out that the brake mounts had deformed slightly and indeed needed facing. Thirty quid later and now my wheel spins silently. I don’t regret a single penny