Please help me not hate my bike's disc brakes
October 16, 2015 1:22 PM Subscribe
I've had a 2014 Brodie Argus for about a year. It's a hell of a bike and exactly what I was looking for. But I can't get the disc brakes to stop grinding and squeaking. Help?
Both the front and rear brakes make a loud grinding sound/sensation when I apply more than a small amount of pressure to the brakes. The brakes otherwise seem to work fine. I commute about 20km daily on paved city streets.
This has been going on for months now, with the sound sometimes going away for a period of time. I'd occasionally take the bike into a trusted local shop and have them tune the brakes, and that would usually solve the problem for a couple days but the sound would quickly come back.
About a month ago I replaced the brake pads for the first time. I thought this would solve it, but again after about a week the problem came back. Then I tried cleaning the rotors with rubbing alcohol. This made the brakes work like a dream... for about a day. Then back to normal. Since then I've cleaned the rotors with increasing amounts of effort about a half dozen times but it's always only a short term solution.
Surely there is a way to fix this? One possibility I can think of is that I waited to long to change the pads and that ruined the rotors? Is that plausible? Any advice is greatly appreciated.
Both the front and rear brakes make a loud grinding sound/sensation when I apply more than a small amount of pressure to the brakes. The brakes otherwise seem to work fine. I commute about 20km daily on paved city streets.
This has been going on for months now, with the sound sometimes going away for a period of time. I'd occasionally take the bike into a trusted local shop and have them tune the brakes, and that would usually solve the problem for a couple days but the sound would quickly come back.
About a month ago I replaced the brake pads for the first time. I thought this would solve it, but again after about a week the problem came back. Then I tried cleaning the rotors with rubbing alcohol. This made the brakes work like a dream... for about a day. Then back to normal. Since then I've cleaned the rotors with increasing amounts of effort about a half dozen times but it's always only a short term solution.
Surely there is a way to fix this? One possibility I can think of is that I waited to long to change the pads and that ruined the rotors? Is that plausible? Any advice is greatly appreciated.
Are you using metal pads or composite? An old MTB trick is to mount one of each on the brake.
posted by TDIpod at 1:40 PM on October 16, 2015
posted by TDIpod at 1:40 PM on October 16, 2015
Response by poster: Thanks for the quick answers. I'd read about bedding in the brakes and figured I was fine since I work at the top of a ~100m hill and ride down it every day, but I don't think I specifically paid attention to how much pressure I was putting on. I'll try this.
I'm not sure about metal/composite, I had a shop put in the new pads.
posted by no regrets, coyote at 1:47 PM on October 16, 2015
I'm not sure about metal/composite, I had a shop put in the new pads.
posted by no regrets, coyote at 1:47 PM on October 16, 2015
Best answer: Entry-level Hayes discs are kinda known for squealing. When a customer brings me their bike and is complaining of squealing pads, I do the following, in this order:
1) Diagnose if it's either the front, the rear, or both that are squealing. On my bike (Avid BB7 Road with 2nd gen rotors) only the front squeals.
2) Drop the pads and measure them with a caliper to see if they need to be replaced. You've already replaced them, but in the future measure the thickness to see if they're in need. There's a chart in the Barnett's manual that shows various pads and their respective thicknesses at which they need to be replaced, or you can dig through Hayes's tech docs.
3) If the pads don't need to be replaced, sand them lightly by rubbing them gently on sand paper or a wide emory board. You don't want to grind them away, you just want to remove the outer glaze. If the pads do need to be replaced, replace the pads. When you replace the pads, it's ok to go from organic to metallic, but not the other way. Organic pads tend to squeal less, but that's not always the case. Personally I find that metallic perform better, so if it comes down to no squeal or better stopping, I take better stopping.
4) Clean the rotor with a lint-free cloth and rubbing alcohol.
5) Install pads and bed them in. When bedding, you never want to bring the bike to a complete stop. Take the bike from 15ish mph to a near stop, let the brakes cool, then repeat, gradually and progressively braking harder. I usually do a run with the front, then a run with the rear, then repeat.
6) If you're still getting squeal in the rear, there's probably not much you can do about it. If you're getting squeal in the front, sometimes it's not from the brakes, but from the vibrations the brakes create, and it's actually the fork that's resonating. I had some bad squeal with one fork, and that squeal went away when I replaced it.
If all else fails, take it to a mechanic and see if they can give it a second look. Squealing is ok. Grinding isn't ok, but maybe what you call grinding I would call squealing. If you're looking for an upgrade, I'm a big fan of Avid BB7, and supposedly their new centerline rotor is supposed to be their quietest one yet. Next time I swap my pads I'm swapping to the centerline rotors as well. Another mechanic in my shop is happy with his Spyre TRP's on his commuter.
posted by spikeleemajortomdickandharryconnickjrmints at 3:56 PM on October 16, 2015 [2 favorites]
1) Diagnose if it's either the front, the rear, or both that are squealing. On my bike (Avid BB7 Road with 2nd gen rotors) only the front squeals.
2) Drop the pads and measure them with a caliper to see if they need to be replaced. You've already replaced them, but in the future measure the thickness to see if they're in need. There's a chart in the Barnett's manual that shows various pads and their respective thicknesses at which they need to be replaced, or you can dig through Hayes's tech docs.
3) If the pads don't need to be replaced, sand them lightly by rubbing them gently on sand paper or a wide emory board. You don't want to grind them away, you just want to remove the outer glaze. If the pads do need to be replaced, replace the pads. When you replace the pads, it's ok to go from organic to metallic, but not the other way. Organic pads tend to squeal less, but that's not always the case. Personally I find that metallic perform better, so if it comes down to no squeal or better stopping, I take better stopping.
4) Clean the rotor with a lint-free cloth and rubbing alcohol.
5) Install pads and bed them in. When bedding, you never want to bring the bike to a complete stop. Take the bike from 15ish mph to a near stop, let the brakes cool, then repeat, gradually and progressively braking harder. I usually do a run with the front, then a run with the rear, then repeat.
6) If you're still getting squeal in the rear, there's probably not much you can do about it. If you're getting squeal in the front, sometimes it's not from the brakes, but from the vibrations the brakes create, and it's actually the fork that's resonating. I had some bad squeal with one fork, and that squeal went away when I replaced it.
If all else fails, take it to a mechanic and see if they can give it a second look. Squealing is ok. Grinding isn't ok, but maybe what you call grinding I would call squealing. If you're looking for an upgrade, I'm a big fan of Avid BB7, and supposedly their new centerline rotor is supposed to be their quietest one yet. Next time I swap my pads I'm swapping to the centerline rotors as well. Another mechanic in my shop is happy with his Spyre TRP's on his commuter.
posted by spikeleemajortomdickandharryconnickjrmints at 3:56 PM on October 16, 2015 [2 favorites]
The number one thing to know is that cheap brakes of all varieties squeal like hell when not perfectly maintained. It's not that they are disc brakes, it's something that happen to all sorts of brakes and pads. By expensive pads and get them professionally mounted. If that doesn't fix it, and the bike still stops, do your best not to worry about it.
posted by 256 at 5:34 PM on October 16, 2015
posted by 256 at 5:34 PM on October 16, 2015
Response by poster: Update for anyone who finds this question later:
Some squeaking is normal for disc brakes, but I took the bike back to where I bought it and they took it for a test ride and confirmed that the loud grinding sounds are not typical.
They still couldn't find anything actually wrong with the brakes, but replaced the rotors and so far that seems to be helping. No verdict on what caused any of this.
posted by no regrets, coyote at 11:39 AM on November 5, 2015 [1 favorite]
Some squeaking is normal for disc brakes, but I took the bike back to where I bought it and they took it for a test ride and confirmed that the loud grinding sounds are not typical.
They still couldn't find anything actually wrong with the brakes, but replaced the rotors and so far that seems to be helping. No verdict on what caused any of this.
posted by no regrets, coyote at 11:39 AM on November 5, 2015 [1 favorite]
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my understanding is that some of the brake pad gets embedded on the disk. if it's not distributed evenly then the brakes grab/release on the embedded parts, squealing, and making things worse (because the grab/release tends to make more pad stuff embed where there already was some, if you get the idea).
anyway, the way to fix this is to make sure that the pad "contamination" or whatever you call it is distributed evenly. and the easiest way to do that is to (1) clean the disks and (2) cycle up the highest hill you know and then back down again, dragging the brakes on the descent. on the descent you want steady, medium pressure (as much as possible without losing speed), for as long as possible. basically you're trying to coat the brakes with pad stuff smoothly.
it may be enough to do a "lite" version of the above, which is to try bake very smoothly and gently for a day or two. again, trying to get the pads to rub all around the brakes without juddering.
posted by andrewcooke at 1:38 PM on October 16, 2015