UPDATE: though this is still a good suggestion if you are having brake problems, the conclusion I came to in the end was just “just buy new pads”. This is partly because mine were actually very worn, which wasn’t helping, but also it’s probably better to be safe than sorry. So try this by all means, but if you still feel your brakes are not working as they should then perhaps it’s better just to cut your losses and get a new set - I did and now they work better than they ever could have just by cleaning them.
I don’t often post bike repair tips, basically because I am a rank amateur and will probably give you some dodgy advice, but here’s a little tip that helped me recently:
I am a disc-brake newbie this season and am incredibly amazingly happy with them! Disc-brakes rule, and I reckon Avid BB5s are a pretty good buy if you’re on a budget - they are just a vast improvement on V-brakes, what can I say!
 | US $8.00 End Date: Monday Mar-15-2010 11:28:37 PDT Buy It Now for only: US $8.00 Buy it now | Add to watch list |
One of the things you have to watch out for, though, is not to get any sort of lubricant on the rotor, or else you are in some trouble - you’ve heard the story of the “woman driver” (always is) who “oiled the brakes” on her car because they were squeaking? Well, there is a very good reason why you don’t want any greasy, oily stuff near your brakes - they are somewhat dependent on friction to work properly, and lubricants exist for the sole purpose of eliminating friction. Need I say more?
Anyway, somehow, whilst cleaning my cassette (which REALLY wants replacing actually) I inadvertently seem to have got some grease on the rear disc rotor because when I subsequently went out for a ride I had virtually zero stopping power on the back brake.
What to do? Well, thank heavens for forums - I put out a plea for help on MTBR (probably the best MTB forum out there) and within minutes I got this solution:
1) Take the wheel off.
2) Take out the pads - easy, just pull out the little caliper in the middle and the pads come completely loose and you can fish them out.
3) Turn your oven on to 200 C and pop the pads in - set the timer for about 20 minutes.
4) While the pads are baking (to burn up any grease/oil), pop the wheel in the bath while your wife is out and wash the rotor with a liberal dose of Fairy Liquid or other household detergent and rinse.
5) Now the slightly dodgy part - get some fairly fine grade sandpaper (i.e. not really harsh scratchy stuff) and give the freshly baked pads a vigorous sanding for 10-20 seconds, using circular motions.
6) With a similar grade sandpaper, go round the rotor with the sandpaper on both sides, making tangential strokes (i.e. not along the circumference and not radially either) first one way, then the other, so you make a light cross-hatch pattern. Don’t go crazy - you want to roughen up the rotors a LITTLE bit, just enough to get some additional friction going, but light enough to get smoothed out after just a couple of big descents.
Now, put it all back together (you may need to loosen both sides of the brake to get the pads in more easily) and you should be back in business!
This worked for me so if you have accidentally lubed up your disc brakes, this might help. As ever, these instructions are provided as-is - any work you do on your bike is at your own risk! In particular, I can’t be sure that all types of pad will take a roasting in the oven - they SHOULD do, they take enough heat when braking, but still, do this at your own risk, like I say.
Now to go and do some braking…
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Posted on May 15th, 2009 by markowe
Filed under: Bike repair
[...] reach a sharp technical descent. I have ridden this before without dismounting, but this time the curse of the brake pads seems to catch up with me and my discs appear to fade, forcing me into an emergency stop into a [...]
I recently had a similar problem-I spilled water with soap on the disks while washing my bike. The front brake was almost useless, and made a horible squeeking sound when I tried to use it. I got a degreasing spray, took off the tire and sprayed it, waited for 5 mins, replaced the brake pads, whiped the disk and put the tire back on. well…I still didn’t have a lot of braking power, but the squeeking was gone. (And after a day of riding, the braking power was back, so now everything is fine :))
All’s well that ends well!
Actually, I think soap shouldn’t be a problem - that gets evaporated and burned up pretty quickly, but it is probably a shock initially as you realise your brakes are useless! It shouldn’t take long for braking power to return with detergent the only problem. However, oil and suchlike are a bigger problem - I guess they are hard to burn up. Maybe with some serious downhill braking sessions to get your discs and pads white-hot - but how you going to do that with no braking power… er…
Anyway, like I said, if in doubt I think it’s wise to just replace the pads (and give the rotors a good wash) - if there’s one thing you want working on your bike, it’s the brakes…
Just use some rubbing alcohol for the disks. It does the job and evaporates quickly. As long as you don’t get a lubricant on your pads/disks, you’re fine.
Don’t make the LBS your one-stop shop for your cleaners, degreasers, lubes, soap… They will gouge you (as if you didn’t know that already). Go to the hardware store.
Take care.