Few things bring as much satisfaction on the trail as a crisply vented brake with a direct pressure point and high performance. This doesn't have to remain a pipe dream. We show you how to get the most out of your brakes with just a few simple steps.
Safety first: The brakes are among the hardest-working parts on the bike and deserve regular maintenance. Spongy pressure points, constant squealing or a lack of braking power are really not necessary. We show you how to look after your brakes properly.
To avoid being surprised by worn brake pads on the road, it is also worth carrying out a regular wear check. The pad thickness should be at least one millimetre. The discs themselves also wear out. The thickness can be reliably checked with a caliper gauge or a special wear gauge. The minimum thickness is often indicated on the disc.
Caution: Disc brakes are safety-relevant components. Anyone working on them should work carefully and without time pressure. 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.
Bicycle disc brake: Basic service
If the disc brakes on your bike squeal like lorries on an Alpine pass, the performance is usually also passé. The result: high manual forces and little riding safety. The problem is usually dirt or inadequate maintenance. Once properly cleaned and fitted with a fresh set of pads, the brakes are quickly ready for use again. We show you how to do it:
1 Remove locking screw
Before you start replacing the brake pads, carefully push the brake pistons back as far as possible between the old brake pads using a flat tool. This creates space for the new, thicker pads. Now remove the locking pin and then the locking screw.
2 Remove brake pads
The old brake pads are now free and can be removed. Simply press the pads together from both sides and remove them from the rear of the brake calliper. Only in exceptional cases, such as with Srams Maven heavy-duty anchor (tested here) the pads must be pulled out downwards.
3 Clean the brake calliper
Clean the pistons on the brake calliper with a clean, lint-free cloth. Brake cleaner or pure alcohol (e.g. isopropanol) can help with heavier soiling and stubborn brake pad abrasion. Careful cleaning improves the function of the pistons and thus increases the performance of the brake. You will also have to invest less time in maintaining the brake system afterwards and adjust it less frequently.
4 Clean the brake disc
The disc itself must also be cleaned thoroughly. Grease residues on the disc in particular can otherwise contaminate brake pads in no time at all. Also use a lint-free, clean cloth and brake cleaner or alcohol and avoid direct contact between the disc and your fingers. Otherwise there is a risk of squeaking and poor braking performance again.
5 Mobilise pistons
Now push the pistons back in again. Roughly clean the old pads before reinserting them. This prevents the pistons from jamming and damaging the new pads. The Shimano pistons made of ceramic (e.g. GRX, Deore, XT) were particularly susceptible to damage. Shimano has already made improvements to the new XT. If you often have problems with braking performance or grinding (Magura?!), you should mobilise the pistons by pushing them back several times. All pistons should extend evenly when the brake lever is actuated. Then remove the old pads.
Special care should be taken with Shimano brakes with light-coloured ceramic pistons. They tilt easily when pressed back and can break. Magura's MT series requires particular care when cleaning and mobilising the pistons. Otherwise the braking performance often suffers.
6 Insert coverings
Now place the pad spring between the two new brake pads, press the pads together from the outside 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!
7 Secure coverings
Now reinsert 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.
8 Brake in correctly
Insert the wheel and roughly align the saddle. To do this, tighten the bolts with the brake applied. Then apply the brakes vigorously and hot with several full braking applications in quick succession. This is the only way for the brake to develop its optimum performance. The brake should be Braking If possible, do not block. Therefore, do not brake to a standstill.
Braking in is crucial for optimum braking performance! The heat removes the separating layer from the new pad and the pad and disc are brought into contact with each other. Even light soiling during operation can be neutralised by the high heat during braking. We recommend: 10 full brakings from 30 km/h to walking speed in quick succession. Do not give up: In the case of heavy soiling, braking performance often only increases noticeably after the 5th full braking application.
9 Aligning the brake calliper
The pads in the caliper settle under load and heat during braking. Grinding can then be quite normal. In this case, the caliper should be centred again with the brake tightened. If the brake still grinds despite the disc running smoothly, you can help with some fine-tuning. Tip: A torch under the caliper makes the central alignment on the disc visible. If there is a lot of lateral run-out, the disc can be straightened by applying a measured amount of force. If this does not work, a replacement is needed.
Why brakes squeal. And: What to do if nothing helps?
Everything has been cleaned and serviced, new pads fitted and brakes applied, but the brakes are squeaking again and not working properly? Stubborn dirt is often to blame. They reduce the coefficient of friction between the pad and disc. The disc stutters instead of gripping. This happens in very quick succession, resulting in the characteristic squealing noise. The braking performance remains low even with high manual forces.
Our experience: Many modern brakes can offer good function, but have their own particular Achilles heel. Magura's MT line needs to be mobilised regularly, otherwise the pistons get stuck. Magura claims to have improved the Louise and Gustav Pro.
Sram's pads are susceptible to squeaking in wet conditions, but then still provide decent braking performance. Organic pads from Shimano (e.g. GRX, Deore, XT) are particularly susceptible to contamination, partly due to a longer service life or some cleaning agents. Here in particular, it is worth hot-braking the system intensively before replacing the disc and pads completely. This often allows the brake to be reactivated. Removing the top layer of pad with sandpaper can also help with minor contamination. Then, as with a new brake pad, intensive Braking announced.
BIKE conclusion: Even a high-end stopper is no guarantee
Everyday BIKE testing shows that many brakes work well if they are well braked and maintained. However, the process is time-consuming and even on new bikes we regularly come across brakes that perform well below average. This can downgrade a Shimano XT or a Magura MT7 to the level of a cheap entry-level stopper. Intensive cleaning and braking can help. This is particularly easy with an e-bike or a long, steep gradient. In case of doubt, however, only a set of new pads will really help to give the brakes a long-term boost. - Adrian Kaether, Editor Test & Technology
Adrian Kaether
Editor
