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I never had this before. Very recent TRP Slate 4. Just put it on the SC with new (Shimano) hose and really good bleed, (I think).
Fantastic lever feel and loads of power but while braking I can feel a pulse through my finger coming from the lever, very weird. It *seems* proportional to the wheel speed.
New Clark rotor, which I took off and cleaned with brake cleaner. I also sanded the pads clean. Re bedded in which didn't take long but pulse back straight away even before the end of the bedding in.
Next step?
Thanks for any help.
Is the disc warped? Spin the wheel and look at the gap between pads and disc or put your finger against the caliper… is the disc catching the pads on the way around?
Not it's really well aligned, I always have tight tolerances and no rubbing. Have had much worse which even if I didn't correct never created pulsing.
I'd have also suggested a slightly warped or bent rotor. Can you remove it and place it on a flat surface to see if there are any gaps?
Rotor is installed the right way? The orientation of the disc might have a difference if the rotor needs to be installed with the arrow facing forwards (at the top) and it is actually pointing backwards.
Absolutely sure the bleed was good and definitely no air in the system?
Do the pads overlap either the wavy outside edge or the arms on the inside?
Do you have a different rotor to experiment with? Maybe swap front and back of they are the same diameter, see if the problem moves to the other brake.
Is the rotor from a genuine retailer?
I've had pair branded disc rotors new from eBay that look the part but are not the same thickness one side to the other. Maybe escaped production rejects or just counterfeit, l dunno. It was measurable with a micrometer.
They give a pulse through the lever that feels like the lever pushing back against you and uneven braking force.
Okay, seems like you've got to the point where we need consider unlikely possibilities.
Could it be that the top edge of the rotor is catching in the caliper? I've seen that happen before when the wrong adaptor has been used
I’ve had that on a bike with Clarks rotors front and rear. Replaced with alternative rotors and it vanished. Assume the Clarks ones had inconsistent thickness as the feeling was very pronounced.
I get this on a few bikes. It's only really noticeable when breaking smoothly for a long period of time. Down a road for example. It's never actually been a problem just a curiosity.
I would have thought that slight distortions in the disk would not do that? If a disc is off centre it is bent by the calipers?
I always assumed it was to do with changes in contact area. Because that would change the breaking pressure. Not really sure.
My guess is that K has the answer. Can you see a spot on the disc that looks different?
Bleeding will make zero difference to pulsing
All bolts torqued up? I assume they probably are, but it's been the cause of vibrations for me in the past.
I had this, it was the pads catching on the spokes of the disc. In my case it was quite pronounced as the disc was worn and the spokes were raised.
Thanks everyone.
Nicely torqued, perfect bleed, nothing catching, friction area bang on where it should be, no visible bend. I can't put it on a flat surface as the rivets are proud of the braking surface.
Anyway I swapped it for an old rotor and braking is perfect, no pulse.
I reckon there are thickness variations invisible to the eye (at least my eye).
I had bought 2 and all in original packaging. The front one is perfect so just lack of luck on the rear. I will return it for an exchange as I would like to have a matching pair.
If all else fail I'll go for Shimano Icetech.
At least it's not my brake.
I've got this on a front Clarks rotor, had a look in good light and there's one patch (which corresponds to the 'slowing' part of the pulse) that just has the surface honing marks, from where they skim the disc or the sheet before it's cut out, that are in a different direction to the rest of the rotor.
It's like the whole disc has been skimmed in one direction and they've gone back across one edge at 90-degrees to the original skim. Because the rogue honing marks are at 90-deg to the direction of the rotor and slightly rougher than the rest it must just grip slightly more!
I reckon there are thickness variations invisible to the eye (at least my eye).
It wouldn't need to be much. Probably need a micrometer to tell
Child #1 has Clarks rotors and I noticed recently that the braking surface isn’t concentric to the mounting holes. Can’t be far off changing the amount of contact patch he has as it spins
pulse per rotation, or more often than that? (6 pulses per rotation)
if the brake pads is larger than the brake track, and rubs on the arms of the rotor, that will cause a more frequent pulsing.