grinding noise from disc brakes

[John Gowland]

Hi, I’ve recently bought a rockhopper 29er & after about 50 miles both the front & rear disc brakes started making grinding noises under heavy breaking. I took the bike back to the shop & told them what was happening & they said that they had re-allinged the pads but after about 2-3 miles they were just the same.
I can’t see anything loose & it all seems to be lined up correctly. any help very much appreciated.

John

[schwim ✓ supporter]

Hi there John,

The sound could be indicative of a few things. Usually, worn brake pads to the point that the metal backing plate of the pad is coming into contact with the rotor, but it can also be one piston stuck and the other is pushing the rotor into the caliper body or something similar. The fact that it’s both brakes and that it happened so quickly leads me to believe that we’re dealing with a bogus setup or loose calipers.

Could you perhaps post a couple pics of the calipers while standing behind the wheel and looking straight down the rotor where the caliper straddles it?

[John Gowland]

thanks schwim, i’ll put some pics on.

[John Gowland]

[img][https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-ash3/q71/s320x320/1185138_10201738890702068_533666627_n.jpg/img]
[img][https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-ash3/q74/s320x320/555005_10201738894822171_76011653_n.jpg[img]https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn1/q71/s320x320/579632_10201738899862297_513238858_n.jpg[/img]/img]
don’t know if you can see anything from these pics as my camera is not very good.

[schwim ✓ supporter]

"John Gowland" wrote

don’t know if you can see anything from these pics as my camera is not very good.

Unfortunately, I can’t see diddly 😢. If you’re using a cellphone, try taking the bike outside into the natural light and holding super-still to take the picture. If you can give us additional angles, that would be great as well. That might get us something a little better to judge by.

[slipfinger]

"John Gowland" wrote

Hi, I’ve recently bought a rockhopper 29er & after about 50 miles both the front & rear disc brakes started making grinding noises under heavy breaking. I took the bike back to the shop & told them what was happening & they said that they had re-allinged the pads but after about 2-3 miles they were just the same.
I can’t see anything loose & it all seems to be lined up correctly. any help very much appreciated.

John

Did you purchase the bike brand new? What make of brakes are on the bike?

First off, if you purchased the bike new, new brakes need to be bedded in. Here is an article on how to bed brakes in.

Secondly, some brakes (Avid) are notorious for making noises during braking. I wouldn’t call it a grinding noise but more of a squealing noise.

Couple other reason that brakes would make noises, they have gotten contaminated some how and would need to be cleaned, or as you LBS suggested they are not aligned right and need to be realigned again.

Lastly if you purchased the bike from your LBS continue to take it back to them until they sort out the issue. This is why I truly believe it is more important to purchase a bike from a shop with a reputation for excellent customer over cheapest prices. just my 2 cents.

Hope you get this sorted

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