wilson_smyth

I have a bike with a set of Shimano BR-MT200 disc breaks.
Recently there has been a very slight rubbing on the front disc. The breaks are not spongy and still feel sharp and quick to stop.
I followed the recommended steps of removing the wheel and pads, pushing the pistons in with the end of a tire lever and reassembling.
That worked fine for one spin, but the rubbing is now back. its very slight but id like to resolve it.

As i can resolve it for one spin by pushing the pistons back, i dont think its a bend/buckle in the wheel or disc.
Could the spring around the break pads need replacing or could bending it out give it a bit more life?
Appreciate any other thoughts on what may cause this?

Thanks!

Noonievut

I'm not a mechanic so I'll just offer some of my own recent experience with disc brake diagnosis:

- regarding the rotor, if you look down at the caliper with the wheel/rotor spinning, do you see it rubbing on one side, each turn? If so, might be the rotor that needs to be straightened (I had that exact experience and corrected it)
- also in my case, I found that the front wheel gave me some grief if I didn't close the thru axle in a specific position
- I'm not following the part about resolving it for one spin...if you spin the wheel hard and it's rotates 10-20 times I would judge performance by noise across this time, not just the first spin

Now you can wait for the experts to chime in...and good luck!

wilson_smyth

Thanks! By ”one spin" I mean a trip out on the bike, for an hour , but I see how that can be misconstrued to one spin of the wheel!

I'm pretty sure it's not a bend/buckle but i will.look at how the wheel/axel is seated.

Noonievut

Haha - I like your version of a spin more so than mine!

This is a busy sub-forum and I've asked a number of questions and I'm always impressed by the assistance. But I'll tell you, when a company finds a way to manufacturer a complete bike that you almost never have to service (from general riding conditions), I'll cry in joy. I realize that a lot is user error, but IMHO bikes and components--while amazing in so many ways--have gotten more complicated and prone to needing more service. Sure, service can be something to embrace and enjoy (I've tried / am trying), but many folks just want to ride and not have to deal with issues.

cxwrench

BRAKE...not break. Unless it's broken.

Did you just push the pads back and not adjust/center the caliper over the rotor? If you don't move the caliper relative to the rotor it's highly likely it will still rub. Unless your caliper was adjusted so it's centered over the rotor AND both pistons are working/moving the same you'll have to do some adjustment.

Marylander

Something like these doodads make eliminating brake rub easy:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

You slip one on the rotor between the brake pads, loosen the caliper mounts, squeeze the brake lever, tighten up the caliper mounts while holding the brake lever, and finally remove the doodad.

Amt0571

I always align calipers by eyesight. I just get behind the caliper and look at the space between the pads and disc and, with the bolts lightly tightened, center the caliper with my hands. When it's in position I tighten the bolts slowly alternating from one to the other.

If I see I can't correct the problem because the rotor is misaligned, I watch closely to find which part rubs and bend it back with an adjustable spanner.

Hit Factor

That's how I do it, but without the doodad!

wilson_smyth

Update from OP:

pushed the pistons back in again with a tire lever, put the wheel back on and used cardboard from a business card as a spacer between the pads and disc to center the caliper on the disc. Just back from a long spin and no issues so hopefully thats it resolved for a while.

thanks for the help and advice all!

Marylander

Yeah, that's the way I used to do it. Somehow it didn't always work the first time for me. With the little doodad it has always worked the first time. It was also super cheap so not much of a risk for me to try it.