I’m having problems with the front brake on a 2 month old bike – I’m planning to ask the shop to sort it but I’d like opinions on the issue first. Brakes are SRAM Rival hydraulic.

After a few rides it was obviously losing power and eventually had no resistance in the lever at all. I took it in to the shop, they bled it and it seemed to work fine after. It was squealing when they gave it back so they cleaned the rotor thoroughly.

I then changed the pads as it was still squealing a bit and didn’t seem as strong as I’d expect. After bedding in the new pads it was great.

Since then I’ve ridden it 3 or 4 times. On Saturday I started thinking it was losing power again but wasn’t sure. Between that ride and today it’s been stored in the house and there’s no way anything got on the pads/rotor. I take it out today and it immediately starts making an incredibly loud screech under any braking (it’s dry out). The brake is still working and the lever feels fine, but the braking power is definitely getting weaker again.

Given the symptoms I’m thinking a slow leak of fluid from the caliper? Should I be asking for a replacement caliper or is it repairable?

sounds plausible its a small leak – thats the usual symptoms. If it is it need new seals if availale or a new calliper if not.

Take the pads out and put a piece of paper between the pads and pistons reassemble and hold the brake on with a rubber band for awhile – see if any fluid staining on the paper

What have the road and weather conditions been like when you’ve been riding it? If at all wet and you’re on busy roads then you could be picking up oily contaminants. My usual routine is to find a decent hill, get some speed up and burn them off by braking. When regularly commuting 20 miles a day, I’d do this weekly.

If the brake judders and squeals as you roll to a stop it’s definitely contaminated with oil or brake fluid.

could be road contamination

Fits description of slow leak from the caliper.

Fits description of SRAM brakes….. 😀

Would road contamination not be noticeable during the ride where it happened? The brake was fine when I put it away Saturday but screeching straight out of the door last night. It’s also only affecting the front.

give the discs a sand.

I assume you’ve checked the rotor is tight? had that numerous times over the years where people complain their brakes judder and squeal only to find the rotor is not tight

I thought my Front brake calliper was leaking on my 105 brakes but the overnight toilet paper test shows it isn’t. It’s just road contamination but I seem to be swapping pads and cleaning rotors much too often. LBS have suggested it’s not doing regular heavy braking, so I’m consciously not dragging the brakes now but doing more off/on braking to see if that makes a difference.

Would road contamination not be noticeable during the ride where it happened?

Possibly not, if the brakes are warmed up when you’re riding and cold after you’ve dragged your bike out of the garage.

As mcnultycop suggests, it’s likely a factor of not needing to brake very hard on a road bike at normal commuting speeds. Feathering/dragging the brakes lightly is the very worst case for pads. This, more than any other bollocks, is the best case for possibly avoiding disk brakes road bikes. Maybe it would be better if smaller rotors 140F/120R were standard.

Tried the toilet paper test, there’s a large evenly spread damp circle. So that looks like a leak?

yup