Originally Posted by
essiemyra
I also have a Priority Continuum Onyx and have been riding it since March 2023. I have put about 1000 miles on the bike this year. This thread is really timely for me. As I have notice that my rear brakes have started to squeak occasionally. Also I thought the brakes needed to be bled. So I brought the bike to my lbs and they looked at the bike. They said the brakes don't need to be bled as of yet, and also the brake pads are fine and don't need to be changed. Also for point of reference I have always had rim brakes not disc brakes.
Any update with the squealing?
Rather than replace my pads again, I went overboard and decided to do a wholesale replacement of the entire braking system and did the install last weekend:
- Levers: Shimano BL-M4100
- Calipers: Shimano BR-MT410 (with resin pads installed)
- Rotors: Shimano SM-RT56-S (160 [mm])
The levers and calipers came as separate packages for the front and rear, with the lines already connected to the calipers and filled with mineral oil, and plugged at the lever end. That made it really easy to do the install, as even though I had to cut both the front and rear lines, very little fluid got out. Thanks to online instructional videos I did my first "lever bleed," and that turned out to be quite easy. (I also bought some specialty tools: hydraulic line cutter, barb inserter and Shimano-specific bleed kit.)
Replacing everything was certainly overkill, but I was going a bit crazy with the squealing and didn't want to do another pad replacement. So far, all is quiet, but that's been the case with each set of new pads I've installed... for a couple of months.
Were I to have taken a more scientific approach, I may have started with just replacing the rotors, as my current hypothesis (essentially untestable now) is that the rotors may have been the culprit and, I suspect, especially prone to resonating. The cutouts on the new rotors are quite different. I also note that the new rotors are marked as being for resin pads only. I presume this is because they're made of a softer alloy. Perhaps that will mean they'll wear more quickly, but perhaps it also means that they'll be less prone to squeal.
I also note that the braking is noticeably better overall. It's not clear to me if that's related to the Shimano versus Promax levers and calipers or, perhaps, just the fact that the Promax components that I replaced were ready for a bleed. I really do think it was silly to replace everything, especially as in the process I finally learned a bit about how to maintain hydraulic brakes, and I could have easily done a bleed for the Promax parts. Part of my motivation for replacing everything with Shimano was so that I'd have parts for which one can easily find instructional videos, and there's a lot more available for Shimano than Promax (although, again, now that I have basic familiarity, I see that one could easily translate the videos from the Shimano platform to the Promax platform).
So, I may have been able to save $100+ in unnecessary part replacements, but I've learned a few things about maintaining hydraulic disc brakes and am (at least somewhat) optimistic that I'll get more than a couple of months of quiet braking.