Cantilever question

[Dare]

I have problem with my m900 cantis. The thing is that rear break began stopping my bike in pulsating motion, if you know what I mean, like it grabs and releases. I tried to switch and to adjust pads but it didn't help. I thought it was something with my rim, but the rim seems ok...My question is if you guys think a brake booster would help and which booster would you suggest?

 

[Double-E F]

What bike are they on?
Just to be sure: have you checked whether the bolts used to secure the cantis to the frame are sufficiently tightened?

 

[Thias]

Will quite possibly still be a problem with your rim. Either there's a dent, a welding seam (if its not a SUP type of rim), a slight misalignment ( we call that an 8 here). Or just a drop of smear or oil.
So first try and clean that rim with some brake cleaner fluid (or alike). Inspect for dents (you have already?) and misalignment. If it was a dent, a sensible man would be able to feel that "pulse" at the brake lever.

I dont think a booster would help. At least not if I understand your problem the right way. (Its the german guy talking to the swedish guy using foreign language... )

 

[Dare]

What bike are they on?
Just to be sure: have you checked whether the bolts used to secure the cantis to the frame are sufficiently tightened?

They are on my Brodie eXpresso and yes, bolts are sufficiently tightened. There is a little play but it is nothing that could cause this and nothing that you don't find on every cantis, including V's. The play is between parts of the brakes not between brake and the frame.
I also visually checked the brakes while braking to see if they move, but they don't. I need to mention that I am heavy fella (98kg) and that this happens mostly when I am going downhill. I am no begginer when it comes to fixing bikes, just wondering if you think it is worth to try with booster and of anyone else has experienced something like this?

 

[Dare]

Will quite possibly still be a problem with your rim. Either there's a dent, a welding seam (if its not a SUP type of rim), a slight misalignment ( we call that an 8 here). Or just a drop of smear or oil.
So first try and clean that rim with some brake cleaner fluid (or alike). Inspect for dents (you have already?) and misalignment. If it was a dent, a sensible man would be able to feel that "pulse" at the brake lever.

I dont think a booster would help. At least not if I understand your problem the right way. (Its the german guy talking to the swedish guy using foreign language... )

First I thought it was something wrong with the rim myself so I gave it good checkout. It is straight, clean and without any dents...changed pads; put some nice kool-stops on there and it was fine first few rides....now it is just being very annoying as the damn problem came back.

 

[t wild]

Sorry for the thread resurrection but you never mentioned the solution. Did you check the rim wasn't egged a bit. It may be straight from above but is it Rising and falling on the brake blocks. If you have a dish in the rim it wouldn't be really noticeable till the blocks had bedded in.

 

[troje]

Re:

If pulsating rythm is faster/slower depending on speed, it's the rim. If not, it's the brake.

 

[k-rod]

rim

 

[bartsince1975]

Could also be bad pad adjustment, if you don't give these pads a propper toe in they will bite and judder. Especcially softer pads.