The SRAM Rival discs on my Polygon Bend RV are junk, and they've been that way from when the bike was new four months ago. Even without any luggage on board they can't be locked up. With any weight on board, they're dangerous. Compared to the Avids on my MTB, they're hopeless. And they squeal horribly too, as well as not stopping the bike....... :-(
Maybe it's not the fault of the discs/calipers: I've read this stuff about how they need to be bedded-in properly and maybe that wasn't done, so I guess I'll get some replacement pads. The original pads have a metal fleck in them, so I'm assuming that they're the metallic type. Should I replace them with organic pads ? I don't really work the brakes that hard: I'm not into screaming down steep hills fully loaded etc...... It's a cruising bike. But I need the brakes to work.
I have been riding Rival discs for a while now and I find them great, stop on a dime. But they were not always so great. Had similar problems to you and took them to my favourite bike shop who bled them. I have ridden organic and metallic pads and have found that proper bedding in is really important. It is possible that during the build the pads were contaminated with a bit of oil (doesn’t take much) and that can lead to squealing and slow stopping. Are the levers a bit squishy feeling? If so have the system bled. If not try removing the pads, clean them and the rotors really well with isopropyl alcohol and maybe a sand them a bit (how to on internet), then try bedding in process all over again. Overall Rivals have been great for me so hope something here will solve your issues.
Thanks Jack. That gives me some hope. I don't think that they need bleeding: they're not especially spongy- maybe just a little...... But I might take it in to the bike shop to see what they think. I did try cleaning up the discs with thinners (what the heck is isopropyl alcohol anyway ?) and roughing up the surface of both the disc and the original pads, but.................didn't really make any difference. Hopefully they can be made to work OK. Cheers, Nitram
Isopropyl alcohol is more commonly known as rubbing alcohol or isopropanol and is widely available at pharmacies and grocery stores. Isopropyl alcohol is one of the most effective ways to remove grease from brake pads, brake tracks and rotors. There is always a spray bottle of it on my work bench. The best thing is that it is really inexpensive and safe to use. You will recognise the smell because hospitals use it to sterilize equipment. Unfortunately it’s been my experience that it’s really easy to contaminate brake pads with just a tiny bit of oil or grease, had to replace almost new pads on my mountain bike. I have heard that some thinners can contaminate pads, but don’t know for sure.
Thanks again Jack. I’ll see if I can find some IA today and clean things up with that instead of thinners which is my usual go-to serious cleaner. Ta Nitram.
Just for the interest of Jack and anyone else with discs that don’t stop and make a horrid racket anyway......... After cleaning the discs and pads thoroughly with isopropyl alcohol and getting no improvement, I decided to bite the bullet and take the GCN advice and hit the front pads with a blowtorch: not an oxy torch- just the LPG. The pads smoked severely as the oil or whatever they were contaminated with burned off, and I heated the pad material til it glowed red a bit. I didn’t put the flame on the steel side: just the pad material itself. I also cleaned the disc (again) with the isopropyl, and went for a ride: excellent ! A huge improvement !! Felt like a disc should, and I went through the recommended bedding-in process and it seemed great. I went on and did the back pads as well, but it was late last night and i didn’t get out to give it a run/ bed-in etc, but I’m confident it’ll be good. I guess it’s a worry that the heating/burning of the pads might have cooked whatever bonds the pad to the steel backing. But I’ll keep an eye on it. So far so good !!! cheers, Nitram
