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Hi
I've got a Marin Pine Mountain 1, which I am really enjoying, apart from one niggling squeak. The front disc clips the pads at a certain point on each rotation. Thinking it was probably a bent disc I ordered a replacement from Chain Reaction, which I have just fitted. Sadly, the squeak remains, and as before it is just in one place.
The brakes are Shimano BR-M445, which appear to have no adjustment options. I have loosened the brake caliper off, put the brake on and re-tightened to no effect. Can anyone suggest anything else to try?
When I was waiting for the bike to come in to the shop I was told that there had been an issue with fork quality, but that this had been addressed. Would a wonkily welded brake mount cause this? Or wouldn't that cause constant noise as opposed to this once a rotation squeak?
I can take it back to the shop, but that is close to a two hour round trip so would rather try other options first.
Any suggestions appreciated!
The put the brake on and tighten the caliper is a stupid method that seems to do the rounds on the internet. It's never worked properly for me across several brands of brake. I know of a few people that do it and they're always adjusting their calipers - I started to sense a pattern 🙂
Loosen the caliper and line up by eye. A torch or light behind can help, as can getting the bike in a stand at the right height and position to see. Be carfeful when doing them back up as they can move as you tighten the bolt.
This is possibly the greatest 'why have I never used one before?' tool since the invention of the needle driver.
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If it's touching at just one point in the rotation and it's not a bent disc it must be the hub flange not being flat or something being trapped between the rotor and the flange. Have you got another wheel you can try?
The caliper should have some side to side adjustment if you slacken the two Allen bolts off a bit.
Once per rotation suggests to me that you should be able to fine tune it by eye. When you say there is no adjustment option, you must be able to move it slightly side to side and up and down when when it's loosened? Normally there's a few mm of play in either direction when you very slightly slacken the bolts off.
Did you make sure the pistons are both pushed right back in before you start?
Ok, took the rotor of again to check nothing behind it causing uneven rotation, pushed the pads back in to the caliper before refitting wheel and tried to true everything up by eye as much as possible. Something worked because it didn't click at all on yesterday's ride! Still feels a bit squealy/juddery at times on longish descents but way better. Thanks for your help!
Get the mount faced.
Had same issue on my steel forked Genesis. Uneven paint on the mount caused squeel, judder and misalignment.
Faced it and all problems gone. A well kitted bike shop should have the facing kit.
The put the brake on and tighten the caliper is a stupid method that seems to do the rounds on the internet.
Yeah, it does the rounds in instruction manuals too. (Avid ones at least) Maybe cos it's a reasonable way to fit your brakes.
If it's hitting at one point in the revolution, it's a slight bend in the disc. Get your adjustable spanner out (make sure it's super clean - you don't want grease on the disc) and get it bent back. Surprisingly easy, and very satisfying when done.
Edit
Ok, took the rotor of again to check nothing behind it causing uneven rotation, pushed the pads back in to the caliper before refitting wheel and tried to true everything up by eye as much as possible. Something worked because it didn't click at all on yesterday's ride! Still feels a bit squealy/juddery at times on longish descents but way better. Thanks for your help!
Could be a slightly sticky piston exacerbating it. But the only thing that'll cause it to ping every rotation will be a slight out of trueness in the disc.
If its only touching at one point in the wheel rotation, it cant possibly be the caliper alignment causing the touch.
If you've replaced the disc then its likely to be the hub (unless you've been unlucky with the discs). I've got a mavic crossride hub which always had a rubbing disc. Tried the disc on another hub, no rubbing. Looked at the disc mounting flange and it wasnt running parallel to the plane of rotation (I think its called run out).
You could try shimming the disc using IS mounting spacers to compensate for the run out of the hub.
If its only touching at one point in the wheel rotation, it cant possibly be the caliper alignment causing the touch.
+1, I can't believe some of the absolute tripe spouted on here sometimes. 😯
I got a Pine mountain one a few weeks back and had a similar issue which was a brake squeal turning into corners. I just loosened and nipped the caliper bolts hand tight, re-adjusted the brake caliper until no rub then tightened. Seems OK so far. Great bike for the money. Paint on the forks is thin though so watch the cable rub!
I've had hope discs come out the packet slightly warped so I'd assume your disc is probably slightly warped too.
easy fix.
go to a well lit area and spin the wheel whilst looking through the gap in your caliper watching the disc. when you see it touch the pads bend that point in the opposite direction slightly and keep doing so until it's sweet.