Disc Brake Problem

[GuinnessMK]

My trusty but ancient (circa 1991 vintage) Stumpjumper Comp got stolen a while back, so I treated myself to a new Cube Acid.

I've done about 120 miles on it so far, the odd commute, a couple of night rides and a few longer trails etc.

It's a brilliant bike and it's clear to see there has been a lot of development in bikes over the last 17 years!

However there is one thing troubling me about the bike, the back brake. It's a hydraulic disc brake, single piston. When I first got the bike I rode it for a few days and then took it back to the shop as it felt like it wasn't releasing. They took it back to the workshop and fiddled with it / fixed it.

Now 100 miles further on I've noticed the back brake grinding when applied. On a car I'd assume the pads were worn down and replace them, so I had a look at them. The pads look reasonably OK (about 2mm of pad left), but the fixed pad is below the level of the caliper, meaning when I brake the mobile pad pushes onto one side of the disc and the disc then rubs on the caliper!

Obviously this isn't right and I'm off to the shop tomorrow for them to have a look at it, but can anyone explain what might have happened? I don't want to be buying new brake pads every 100 miles!

Cheers

Mike

[Cabinet Enforcer]

Sounds rather like your grease monkey doesn't know one end of a pair of pliers from the other

Either go and play hell, or fix them yourself, disc brakes are hardly complicated.

According to a quick google the 2008 acid should have M485 shimano hydraulic calipers, these are twin opposing piston, not fixed. Which calpiers do you have? If shimano you can get full fitting and setup sheets from their website.

[GuinnessMK]

Thanks!

I have Hayes Stroker Ryde calipers on mine for some reason (probably 2007 stock)!

I didn't realise the caliper mounts are adjustable. (Shows how long it has been since I worked in a bike shop). I'll loosen the caliper mounting bolts, centre them up myself and see where that takes me.

Cheers

Mike

[Cabinet Enforcer]

GuinnessMK said:

Thanks!

I have Hayes Stroker Ryde calipers on mine for some reason (probably 2007 stock)!

I didn't realise the caliper mounts are adjustable. (Shows how long it has been since I worked in a bike shop). I'll loosen the caliper mounting bolts, centre them up myself and see where that takes me.

Cheers

Mike

The hayes strokers appear to be newfangled, so it's a 2009 model. If you took the wheels out to transport the bike then one of your pads may not be correctly positioned, I think some hayes units have the pads held with just a spring. There should be pad fitting destructions with the bike.

[aciddrop616]

as said, one pad moves, one doest, the one that doesnt will wear down, you jsut needs to twist the allen key on the back of the caliper to push it out a bit more.

Hardly rocket science

thom

[GuinnessMK]

Thanks Thom!

Whilst I agree that it isn't rocket science it's new to me, hence why I asked what to do.

I did mention in my original post that the last bike I bought was made in 1991. I also mentioned that I used to work in a bike shop. So back in the early 90's I built up literally hundreds of bikes and serviced many more. I could even build wheels. Back then V brakes where new technology! SIS had just been invented.

But that was then and this is now. I didn't get a manual for the bike when I got it and unless someone tells you how to adjust the brakes I'm not going to know instinctively.

Mike

Edited by GuinnessMK on Monday 13th October 19:17

[Parrot of Doom]

To centre them up, wind the non-moving pad out a bit, loosen the calliper and then hold the brake lever tight - so the pads are gripping the disc. Still holding the lever, tighten the calliper at that point.