New brake pads losing power straight away

mediamonkey

Last week I replaced my rear pads, bedded them in, went for a ride and they worked perfectly. I put the bike in the garage for three days, take it out and it's like someone has spread lard over the rotor: barely enough friction to lock the wheel, and it's squealing like a howler monkey.

The last set of pads developed the same problem but I thought a thorough clean and new pads would fix it. Obviously not. I can't see any obvious cause and there's no loss of pressure from the brake lever. Brakes are Shimano M596. Any ideas?

njee20

Either you have a contaminant on your rotor, or you have a leak.

mediamonkey

I can't see any obvious oil leakage. Are the piston seals the most likely spot?


Edit: OK, on close inspection I can see a little drip of fluid on the frame below the calliper. The bike is only 18 months old so this should be a warranty job right?

On a related note I'm really not impressed with the kit on modern bikes. Bottom bracket was trashed after 9 months. Freehub trashed and replaced last week. Now the calliper is leaking. My first MTB, a 1990s GT, got ridden in all weathers, minimal maintenance and after 15 years of use was only on its second BB and second rear hub. Pulled it out of the shed last week to fix it up as a runabout and it's still working fine! Truly they don't make 'em like they used to...

andyeb

mediamonkey wrote:

On a related note I'm really not impressed with the kit on modern bikes. Bottom bracket was trashed after 9 months. Freehub trashed and replaced last week. Now the calliper is leaking. My first MTB, a 1990s GT, got ridden in all weathers, minimal maintenance and after 15 years of use was only on its second BB and second rear hub. Pulled it out of the shed last week to fix it up as a runabout and it's still working fine! Truly they don't make 'em like they used to...

I think this is a general problem with newer bikes these days and I think the rise of online shopping is partly to blame, where customers get into a spec-driven mindset. Manufacturers respond by bringing out bikes with impressive specs, but something has to give, so they economise on the more hidden parts, like the bottom bracket and headset.

Terrytibbs

mediamonkey wrote:

I can't see any obvious oil leakage. Are the piston seals the most likely spot?


Edit: OK, on close inspection I can see a little drip of fluid on the frame below the calliper. The bike is only 18 months old so this should be a warranty job right?

On a related note I'm really not impressed with the kit on modern bikes. Bottom bracket was trashed after 9 months. Freehub trashed and replaced last week. Now the calliper is leaking. My first MTB, a 1990s GT, got ridden in all weathers, minimal maintenance and after 15 years of use was only on its second BB and second rear hub. Pulled it out of the shed last week to fix it up as a runabout and it's still working fine! Truly they don't make 'em like they used to...

I doubt it'd be fixed under warranty, it depends on the brake but most manufacturers have a 1 year warranty but it depends. To be honest though, things wear out and seals will need replacing some time or another. If your brake needed a bleed the oil could be mucky and could have affected the seals.

It's not a huge job though, take it to a shop and expect to pay around £20-£25 for a bleed and seals. If it's a crap brake anyway it may be worth upgrading.

The kit on modern bikes is fine, it just depends how much you spend on the bike, how you treat your bike and how much it gets looked after. Things will wear out and break at some point.

Terrytibbs

Also forgot to mention. If it's leaking and you've got oil on your pads, you'll need new pads and you'll have to at the very least rub your rotor down with emery paper to remove any burns or glazing. Otherwise, it'll still be noisy once the leek is fixed.