In this article, we use so-called affiliate links. With every purchase through these links, we receive a commission from the merchant. All relevant referral links are marked with . Learn more.
CONTENTS:
Why do disc brakes drag?
Without pulling the brake lever, the brake pads rub lightly against the disc. Five causes - five solutions.
1 Too much brake fluid: Occurs again and again with new brakes as delivered. The pistons cannot retract far enough. The only thing that helps is to correct the brake fluid level. You must then Bleeding the brake.
2 Brake disc not centred: In this case the Loosen and realign the brake calliper.
3 Impeller installed at an angle: This can happen on bikes with conventional quick-releases. Open the quick release and readjust it.
4 Brake disc bent: Sometimes it helps to apply the brakes really hot (be careful not to overheat!). Otherwise Bend carefully by hand or with a straightening tool.
5 Piston stickingPiston and Clean the brake calliper with brake cleaner.
In our E-MTB special "All the facts for beginners" you will find even more useful information:
Safety note
For your own safety: The brakes are one of the hardest-working parts on the bike and deserve regular maintenance. A regular check is worthwhile so that you are not suddenly surprised by worn brake pads on the road.
ATTENTION: Disc brakes are safety-relevant components. Anyone tinkering with them should know what they are doing and, above all, work carefully. A check ride after maintenance never hurts. If you don't have sufficient experience in tightening disc brakes, it's worth going to a bike workshop and getting advice from experts.
Change brake pads
How long the pads last depends heavily on the external conditions. In muddy weather, a pad can be worn down after just one long day on the bike. The pad thickness should be at least 1 millimetre. The discs also wear out. The thickness can be reliably checked with a caliper gauge or a special wear gauge. The brake disc should not be thinner than 1.5 millimetres. Discs that are worn to varying degrees should also be replaced.
Changing the brake pads on MTB disc brakes - here's how:
1. remove the locking screw
Before you start replacing the brake pads, use a flat tool to push the brake pistons back as far as possible between the old brake pads. This will create space for the new, thicker pads. Now remove the retaining ring and then the retaining screw.
2. remove brake pads
The old brake pads are now free and you can remove them. Simply press the pads together from both sides and remove them from the rear of the brake calliper.
3. clean the brake calliper
Clean the pistons on the brake calliper with a clean, lint-free cloth. Brake cleaner helps with heavier soiling and stubborn brake pad abrasion. Careful cleaning improves the function of the pistons and thus increases the performance of the brake.
4. push back the piston
To be on the safe side, push the pistons back in again. Before doing so, however, roughly clean the old pads and reinsert them. This prevents the new pads from being damaged when they are pressed back in. Then remove the old pads.
5. insert pads
Now place the pad spring between the two brake pads, press the pads together with your fingers and insert them into the holder between the brake pistons. Some manufacturers differentiate between left-hand and right-hand pads. It is essential to ensure the correct arrangement!
6. secure coverings
Replace the brake pad locking screw. Do not forget the retaining ring of the screw. Older brake models sometimes still use a cotter pin, which must be bent open with pliers.
Fitting the brake disc
Replacing the brake discs is not rocket science. Depending on the standard - centre lock or six-hole disc - different tools are required.
Six-hole disc
The brake disc is fastened using six bolts, which are tightened crosswise with a torque of 4-6 Nm, depending on the brake model. The screws are provided with a screw lock to prevent unintentional loosening of the brake disc.
Centrelock standard
Centerlock discs are mounted with a ring in the centre of the disc. A conventional bottom bracket spanner is used as a tool. Centrelock discs can also be fitted using a nut. The torque required to tighten the ring is significantly higher: 40-50 Nm. The toothing of the hub and end ring prevents the brake disc from coming loose. Advantage of Centrelock: Fitting is much quicker. Disadvantage: Some manufacturers do not offer suitable discs for the Shimano standard.
Observe the running direction
Caution: When fitting the brake discs, always observe the correct running direction. Shimano usually marks them with an arrow.
Aligning the brake calliper and adjusting without grinding
The brake calliper should be exactly parallel to the disc - this allows the brake to apply powerfully and prevents it from dragging.
1. loosen the brake calliper
Loosen the two screws on the brake mount. Now pull the brake lever until the brake pads are firmly in contact with the disc. Tighten the screws again with the brake lever pulled.
2. visual inspection
After tightening the fastening screws, the disc should run exactly in the middle between the brake pads. If this is not the case, repeat step 1 and readjust the brake calliper. A light-coloured paper on the floor helps with the visual check. | Photo: Georg Grieshaber
3. align the brake disc
If the disc grinds irregularly and "wobbles" despite the brake calliper being adjusted, it is warped. In this case, use a special straightening tool to clamp the edge of the disc or use your hands and a cloth to protect it from grease to carefully straighten the brake disc. To be on the safe side, clean the disc with brake cleaner afterwards.
The right tool
These are the most important tools for brake assembly:
