Shimano MT420 front brake (less than a year old), new 3rd party 203mm floating rotor, new TUV rheinland certified 3rd party "ceramic sintered" pads. Rear is same setup with 180mm rotor.
I was coming down tight, twisty mountain roads, dropping about 330m quickly. Not dragging the brakes, but hard bleeding off speed when blind corners appeared.
Lever pulled in, braked for a bit, then the power just vanished. Under continuous hand pressure the lever went in further, braking action, and then lost power again. It repeated this a third time. The lever just kept going in, in stages. Very weird. Never experienced this before so no idea what happened.
Any ideas what went on? Problems with the 3rd party gear? Or a bleed issue?
If you aren't loosing fluid anywhere then either air in the system or internal seal leak in the lever is my guess
My guess would be a caliper seal blowing with the heat and fluid escaping and being burnt off
I'll have a check how the brake is working tomorrow in the daylight, and cooled down. Look for any residue on the caliper and lever. Then if it looks okay, I guess I'll be watching YouTube videos on how to bleed this thing over and over.
Otherwise I'm going to have to buy a new front brake that can manage heat, if that's the issue here.
https://postimg.cc/gallery/WkZN18j
Okay, I've just found the time and energy to do maintenance and here's some pics of what's left of my brake pads. They have dissolved. So I'm guessing it's not a bleed issue, or a seal issue. It's a "did they hit the right part of the rotor" issue? Or what? I wasn't riding in sand or salt.
What do the rotors look like? What have you been cleaning them with? It looks to me like they've been chemically etched rather than worn. If it was wear, I'd expect the rotor to be shredded too.
Maybe that’s just a case of being crap pads? I think some of the aftermarket pads are produced on the cheap and QC isn’t what it could be.
I’ve got on ok with uberbike pads but I think they had a batch where the pad material came away from the backing.
Maybe try Shimano branded sintered pads and see if they’re up to the job?
Buying genuine parts is problematic where I am. I pay about £5 for these pads.
One side seems to be worn more than the other. I can't get the pistons to go back in properly on that side. I ought to do a bleed, but I don't want to mess stuff up. The bike is sitting on the work stand waiting for me to hit it tomorrow. When I'm sober. We are close to a media-holiday here where a quarter of a billion people will want to travel and see family and they're freaking out over a few hundred cases of Omicron.
I may even throw my hands. Up, take some new pads and cycle to an LBS and let themtry and sort this out. But 25 years of sorting my own gear out and it's beffudling me.
