Road disc brake problems

huntswheelers wrote:

Daily issue here in the workshop for Road Bikes on Discs….. not going to say Told you So….lol. 

 It was in my workshop too; I too will try to resist the “I told you so”. The braking may be good, but the daily living with them is much more onerous. A road bike to me should be a thing of quiet beauty, which is not easily compatible with discs, either aesthetically or aurally.

Guys, I’m actually amazed

Guys, I’m actually amazed people are concerned about sanding the discs. This is a well established step in trying to solve contamination/squeeling issues. 

Remember when they are supplied new in the box, they are not a ‘polished machined surface’ but a matt, buffed looking surface, which almost looks like someone has taken a fine sandpaper over it, funnily enough.

Obviously you shouldn’t be taking a belt sander to them, and obviously you shouldn’t be sanding away for hours and actively thinning the disc down, but I can tell you that for various reasons, I’ve had cause to sand discs numerous times, all you’re doing is taking them back to the state they were in when brand new, so yes, you have to bed them back in again, but no, you’re not leaving them more prone to contamination, no you’re not weakening them, no you’re not doing any permanent damage, etc. etc.

That said, you should be using wet+dry, not mega coarse sand paper, and you should probably be putting that file down… 

Edit: re: prone to contimination, I guess if you sand the rotors but continue to use contaminated pads, then yes, you would be depositing contaminated material on the rotor. This step presumes using new pads…

I don’t know if this will

I don’t know if this will help on disc brake rotors, but as a chippy, when our ciricular saw blades get ‘contaminated’ with resin etc from knotty wood, leaving them soaking overnight in oven cleaner works a treat, as nothing else (turps / meths / petrol) shifts that stuff. Might be worth a try. I’d be really wary (as mentioned before) of sanding the discs. They’re a  polished machined surface, and unless you’re polishing with something like 4000+ grit wet and dry, then you’re likely to leave a surface which is far more likely to become ‘conatiminated’ due to the small scratches retaining contaminant materials.

http://www.discobrakes.com/?s

http://www.discobrakes.com/?s=0&t=0&

some great prices here and the quality is very good

PaulBox wrote:

I would recommend Uberbike components for pads, not worth messing about, just change them out.

https://www.uberbikecomponents.com/category/324/Disc-Brake-Pads

I was going to say exactly the same and in fact their website looks very similar to Disco mentioned earlier, could they be connected ?

In all the years I’ve been

In all the years I’ve been using disk brakes (mountain bike and hybrid), I’ve never once taken sandpaper to the rotors or scrubbed a set of pads to the extent described above – I use Muc-Off and then car shampoo to wash the bikes and give the brakes a good wash with that at the same time.

I’ve used meths and brake cleaner a couple of times when I’ve serviced the calipers and cleaned the rotors.

When I’ve had squealing brakes, it’s usually been down to a sticky piston meaning the pad on one side isn’t releasing properly (rode my sister’s bike from her house to my house with a howling front wheel because of this – it was a lot quieter when I rode it back!).

If you’ve got vibration, then it’s also worth checking the hub bearings are ok – this is currently the problem on my mountain bike and will (kids permitting) be sorted this weekend.

IanEdward wrote:

I’m a little out of touch with Shimano brakes, but I think leaking callipers causing contamination was a fairly well recognised problem.

I had this. As did several other owners of Specialized Source Comp Discs I happen to know (Shimano BR-M506 brakes). Only solution we found was to replace the brakes.

Once I guessed what was happening (and that took me a while) I could test it by putting the bike up on a workstand, cleaning thoroughly with alcohol and then putting a small piece of tissue between the back of the pads and the cyclinders.

If I put it in and left it it would come out clean. If I braked hard a few times however it would come out with a circular stain of what looked like oil, but was presumably brake fluid.

That tallied with what I noticed with riding the bike. I would clean everything and the brakes were quiet. Then they would slowly get louder as I rode but particularly if I had to do any hard braking. As time went on it would get noisy quicker so I guess the leak was getting worse. Eventually the noise would make babies cry, people to lean out of their windows to see what happened and for every man and his dog to tell me I either needed to clean my brakes, or oil them.