One of the big advantages of hydraulic disc brakes is their relative lack of maintenance requirements, but that doesn’t mean there’s nothing to do to keep them operating at their best.
Here’s our simple guide to keeping your new disc brakes performing at their best, with rotor cleaning and pad changing tips we’ve learnt from (sometimes bitter) experience.Pad changes
Disc brake pads normally last a lot longer than V-brake pads but they aren’t invulnerable and soft compounds will still suffer fast in gritty winter conditions. If you burn pads through to the metal backing then not only will your braking power suddenly disappear, but it can also pump enough heat through the fluid to lock the whole system up. For these reasons always check you’ve got pad left before a ride, and if you’re heading out on an epic or wild weekender, take spares with you. As a rule of thumb if the pad material is thinner than a 1p piece get some spares ready.
Once they’re looking worn out, we suggest you replace them in the comfort of your shed, as hunting for vital small parts amongst trailside grass is never much fun. Make sure that you have exactty the right pads too. Nearly all brakes – even between the same manufacturer – use different pads shapes sizes and even fitting mechanisms. You won’t be able to bodge one between the other.
Once that’s all sorted the first stage is to remove the wheel and the disc rotor.
Then work out how your pads are held in place. Some are just held in with a push fit spring clip and magnets while others are held with pin/s that run through the top of the caliper body. If it’s the latter watch out for the small metal springs that are often placed between the pads to help them spring back into place. Check exactly where they sit now to make putting them back correctly easier. Now carefully remove any split pins or safety wires and unscrew / pull the locking pins straight out. Now the pads can be pulled out of the bottom of the caliper one at a time.
Now is a good time to give the inside of the caliper a quick wipe round with the corner of a rag and a bit of soapy water. Avoid aggressive cleaners as they can damage delicate hydraulic seals.
To install new pads simply reverse the procedure, but make sure that you avoid touching the braking surface of the pads to avoid greasy contamination. That said, a small dab of high temperature grease (we normally use ‘Coppa-slip’ or similar) can help to stop the minute vibrations that cause the shrill screech that plagues some brakes. If the system uses a spring to space the pads, then it’s often easier to sandwich the spring and pads together and fit them all in one go.
Once the pads are securely in place, replace any locking pins and spacing springs and check the pads retract away from the rotor cleanly for a smooth spin.
If you’ve got a ‘Closed’ system or one with pad adjustment on the caliper itself you’ll need to fully open the pad spacing to give room for the new pads. If you find they still don’t fit, very carefully ‘leak’ a small amount of fluid from the caliper, but make sure you keep fluid away from the pads and rotor.
As the pads are new you’ll need to allow time for them to break in and give you full braking power. The time this takes depends on the brakes and the pad compound, but don’t go braking too late or too hard until they’ve settled.Pad contamination
Although they look fairly hard chunks of material, brake pads have a real weak spot for soaking up any greasy lubricant or brake fluid that comes near them. Once contaminated their braking power all but disappears. Rapid emergency cleaning with rotor cleaner, or a wire wool pad can help a bit and we’ve even heard of some folk getting decent results from baking the pads in an oven to remove residue. You’re better off just making sure you keep any sort of lube spray or fluid spills away from them in the first place though.Rotor cleaning
Stuck on the opposite side of you wheel from lube hungry chains and sprockets, brake rotors are hard to keep totally greaseless. Luckily the steel baking surface of rotors are a lot easier to clean, but using the wrong stuff can contaminate the brake pads themselves.
Motorbike and car disc brake cleaner might sound ideal, but they often leave a film of residue on the braking surface. As car and motorbike systems use massive amounts of heat they can burn through this residue without worry, but bike brakes will suffer. Bike disc brake cleaners might seem expensive compared to big cans down “Auto Mart” but they are designed specifically to clean off crud and then evaporate entirely, leaving the braking surface perfectly clean. Makt, Finesse and other bike lube companies all produce their own blend.
If you’re finding build up of mud inside the calipers a problem then it might be worth changing the shape of your disc. ‘Wavey’ outer edges like those on the Hope Mini rotors help push through mud and other debris while the buzz saw blade design of Planet-X’s Rotorvator will probably clear small trees from your path too!
For more information on different pad compounds and rotor sizes see our opening disc brake feature.Next Week
Although cable disc brakes generally need treating in exactly the same way as their hydraulic brothers, there are some tweaks worth knowing to keep them performing predictably and powerfully. So tune in next week if you’re stopping with string.