Fettling SRAM rival hydro discs

graeme_s-2

This is my first disc braked bike, so after a bit of advice from wiser heads.

The bike has SRAM Rival hydraulic brakes, is two years old and has been used as a daily commuter in all conditions. Last changed the front pads 3,500ish miles ago, and the rears 1,500ish miles ago.

Most of my braking's on the front, although I do try and give the rear a good hard pull at least once a ride.

The front brake still feels pretty solid, but the rear is not good. If I pull the rear by itself it is not confidence inspiring and squeals. A few weeks back I gave the caliper a quick blast with some muc off disc brake cleaner and pumped the lever a bit (I was wondering if the pistons had got a bit gummed up), that seemed to improve things very slightly, but it's not as good as it used to be, or as good as the front. If I pull the lever as hard as I can it goes all the way back to the handle bar.

I can remember riding down a hill bedding in the rear pads when I installed them, and braking only on the rear brake I had to be careful not to lock the wheel up. Now I can haul the back brake on by itself as hard as I like and there's no chance it'll lock the wheel. If I'm braking with the front brake as well, then the rear is still able to lock the wheel.

So, is it worth trying changing the pads (although it seems unlikely to me that they'd be more worn than the fronts)? Or does it sound like a fluid issue? Should I be considering bleeding or changing the fluid?

meanredspider

It may just be that the rears have got contaminated over time and a new set of pads is in order. That would be my first step. I tend to order pads in sets of 5 pairs or more from whoever is selling them at a good price for a reputable brand. Superstars have been fine. If they are hydro and you give the disc a good wipe down with an appropriate solvent, you should be able to just pop the new pads in and bed them in. Whilst the pads are out, it's probably worth giving the calliper and pistons a clean up. Carefully extend the pistons, taking care not to over extend, and wipe them down with the same solvent.

graeme_s-2

Thanks, I'll give that a go before getting more drastic.

There are superstar organic pads front and rear in there at the moment, but superstar are out of stock, not expecting them back in this calendar year.

Had 2 pairs of SRAM's own organic pads delivered from Wiggle yesterday (which must have been what was fitted to the bike to start with).

I'd gotten a bit bullish that being a heavier chap (plus my work bag) and doing a lot of stop-start city centre riding on my commute I was somewhat contamination resistant (in that anything that got on them would be burned off quickly), but it does sound plausible they're contaminated. I'll have a go changing pads this weekend.

meanredspider

Graeme_S wrote:

Thanks, I'll give that a go before getting more drastic.

There are superstar organic pads front and rear in there at the moment, but superstar are out of stock, not expecting them back in this calendar year.

Had 2 pairs of SRAM's own organic pads delivered from Wiggle yesterday (which must have been what was fitted to the bike to start with).

I'd gotten a bit bullish that being a heavier chap (plus my work bag) and doing a lot of stop-start city centre riding on my commute I was somewhat contamination resistant (in that anything that got on them would be burned off quickly), but it does sound plausible they're contaminated. I'll have a go changing pads this weekend.

It's worth a try to start with. I've become pretty complacent about my rear brake on the Volagi as, like you, I hardly ever use it. When I had the faulty original HyRd caliper descending Alpe d'Huez, it was useful to have a rear brake when the front lever started touching the bars. You might find that the fluid needs changing if the lever has got spongy but that would be my last port of call.

graeme_s-2

Well that's it. In day to day operation the front is perfectly good enough by itself, but if something were to suddenly go wrong with it, at the moment I wouldn't have much confidence in my rear brake to stop me.

I have to say I was impressed when I realised I'd done 3,500 miles since I changed the front pads. I literally haven't done a single second of maintenance or fettling on the front brake in that time.

graeme_s-2

Finally got round to looking at this properly last week. Replaced the front pads (which were nearly down to the metal), and also the back pads (which had plenty of wear left on them, but were not inspiring confidence). Gave the discs a good clean with disc brake cleaner, and bedded them both back in.

Rear was definitely better afterwards, but the lever still had loads more travel on it than the front lever, and with the pads out I could see the pistons didn't seem to be emerging equally, or at the same rate as the front. Tried to clean them up a bit with disc brake cleaner, didn't seem to make any difference.

Put my bike in with a mechanic to change the bottom bracket the day after, spoke to him about the rear brake, he thought it needed bleeding. He bled it, and the rear brake is now as good as the day I unpacked the bike.

I tend to be a bit crap at keeping on top of maintenance, but with everything cleaned and fettled, the brakes sorted out and a new bottom bracket the bike is an absolutely joy to ride again. Only sound while riding is the noise of tyres on tarmac - bliss!