Disc brakes on a road bike: The most important tips & tricks
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Even if we still receive letters from readers wishing for tests of rim brakes and complete bikes with the old technology to return, there is no alternative to disc brakes on road bikes. About ten years after the major bike manufacturers began to gradually switch to the new technology, the rim brake has completely disappeared from the market - apart from a few exotic models and individual frame builders. If you want to buy a new bike today, you almost inevitably have to get to grips with the new technology.
It was not only better products and increasing acceptance among cycling professionals that were decisive for the gradual but now widespread breakthrough. Above all, it is likely to be the experience that users have gained with them over time. The consistent, high braking power, better modulation and reliable function, regardless of the weather conditions, convinced more and more road cyclists in parallel with the triumph of the gravel bike. And these are just the directly tangible arguments. There are also side effects: Anyone travelling with carbon rims no longer has to worry about heat problems and expensive special pads. Frequent riders are pleased that disc wheels last almost forever. With a lateral runout or cracked spoke, the disc racer can usually continue to ride, whereas the rim brake version sometimes cannot. Once a disc, always a disc, that is usually the tenor of those who have made the switch. Anyone who has tried them once or even experienced the advantages in difficult situations is happy to accept the minor disadvantages.
On the way there, the disc on the road bike had a hard time. It's not just the extra weight of around half a kilo that is often criticised as a race-deciding disadvantage. Complicated and barely visible technology, faults that are difficult to rectify in the wild and the need for special tools are still causing traditional racing cyclists to have reservations. Yet the hydraulic disc is not that difficult to handle once you know how it works. On the contrary: a tight and well-adjusted system works significantly longer maintenance-free than a rim brake, because no Bowden cable will stretch or wear out.
Our two-part article shows that adjustment and maintenance are not rocket science. The workshop at home is sufficient for most jobs. Our professional mechanics will show you tips and tricks so that you don't have to go to a specialist dealer for minor issues.
Check disc brake
Is everything running smoothly?
Visual inspection: With the bike in the assembly stand and with the front or rear wheel turning, check: Are there any oil leaks in the lines to the brake calliper and the grips? Are there any visible or tangible grooves on the brake discs? Do the discs wobble or run flat, are grinding noises audible? Also check the tight fit of the brake callipers on the fork and rear triangle and the brake levers on the handlebars.
Light on both sides
The brake system is optimally adjusted if there is an equally large light gap to the brake pads on the left and right of the disc. This position also shows whether the pads still have enough flesh. It becomes critical when the pad thickness is less than 0.5 millimetres.
Counting tenths of a millimetre
If you travel a lot in the mountains, you should check the wear on your brake discs at regular intervals. In this case, there are still a good two tenths of a millimetre to the wear limit of 1.5 millimetres, at which point the disc must be replaced at the latest.
Not down to the metal
Depending on the intended use and riding style, brake pads wear out at different rates. The example in the photo shows a brake pad that has been rasped down to the backing plate. The manufacturer Shimano, for example, recommends fitting new pads at a thickness of 0.5 millimetres at the latest.
Maintenance and repair of disc brakes is not rocket science. For me, the rim brake has had its day. - Matthias Fischer, TOUR mechanic
Adjusting the disc brake
Hand-friendly
The better the brake lever sits in your hand, the more precise, durable and powerful it is to operate. The grip width can be individually adjusted on most levers. On current SRAM levers, the adjustment screw at the upper end is concealed behind a small decorative cover; the grip width is adjusted with a Three-millimetre hexagon socket adjusted by turning to the left or right. Similar to Campagnolo or Shimano, whereby the adjustment on the Japanese is only visible when the grip rubber is removed. With Campagnolo, the screw is located in one of the recesses on the front of the brake lever.
Aligning the brake calliper
If the disc grinds in the brake, the brake calliper should first be realigned precisely. To do this, loosen the fixing screws until the brake calliper can be moved freely. Then apply the brake until the brake pads pinch the disc and the brake calliper aligns itself. With the lever pulled, screw the brake calliper on hand-tight. If the grinding is not eliminated, repeat the procedure. Check that the light gap is the same width on both sides of the disc and that the distance between the pads and the disc is symmetrical. Then tighten the fixing screws to the specified torque. If the brake calliper keeps tilting when tightening, this may be due to the fixing points not being flat. Sometimes only paint residue needs to be removed. Otherwise, you will need to help with the alignment by hand or mill the mounting flat.
Bending without breaking
Careless transport of the wheels when they are removed can cause the brake discs to develop lateral run-out. This can be remedied with a suitable Brake disc straightening tool, whose slot fits exactly over the disc, can be corrected by gentle levering.
Rim brakes are technically simple, but require a lot of manual force on steep descents. I therefore prefer disc brakes, which are easier to modulate and provide powerful deceleration. - Sandra Schuberth, TOUR online editor
Disc brake: maintenance and installation
Clip off!
Removing the brake pads is easy with the right tool. Use flat-nose pliers to loosen the locking clip on the guide screw, which is then unscrewed using a small hexagon socket. Caution: The small safety clip can easily be lost.
Package solution
Once the retaining screw for the brake pads has been removed, the pads including the expanding spring, which presses the pads into the correct starting position when the brake lever is opened, can be pulled out upwards with a slight jerk. The spring, which fits snugly around the pads, should be handled with care so that the delicate part does not bend.
Placeholder
With removed coverings, a suitable Transport lock between the brake pistons, otherwise there is a risk that they will extend so far that the disc no longer fits due to unintentional actuation of the brake lever.
Well sanded
Glazed or dirty brake pads can be made fit again with 80 grit sandpaper. Glazed brake pads, i.e. those that have not been braked in properly, can be recognised by their smooth sheen, which can usually be easily roughened again. A cleaning cloth soaked in brake cleaner or white spirit can still help with superficially oil-smeared brake pads. However, the pads often soak up the fluid and need to be replaced.
Well sprung
Only undamaged expanding springs may be reinstalled. Particular attention must be paid to the small lugs on the open side. If they are bent inwards and do not fit snugly around the pad, they cause high-frequency squeaking by rubbing against the disc. Attempts to straighten them usually fail, so it is better to buy new ones. They are usually included with new pads.
I think disc brakes are simply better than rim brakes. Full stop - Wolfgang Papp, TOUR picture editor
Fortunately standard!
While different variants such as press-fit or BSA with different crankshaft diameters are used for the bottom bracket, Campagnolo, Shimano and SRAM use a standardised lockring to secure the brake disc. The appropriate tool is available from Shimano, for example, with the designation TL-FC36. The insert for the half-inch torque spanner is also available as a matching socket.
Clean disc
At the end of any assembly work in the vicinity of the brake disc, it should be cleaned with a special cleaner should be cleaned. This reliably removes dirt, oil or grease, which can otherwise promote wear, reduce braking performance or cause noise.
Troubleshooting
Brake pistons that have been pushed out cannot be pushed back in by hand. You can help yourself with two old brake pads, which you can spread open with a large screwdriver. If the pads are still to be used, insert a cloth between them. If the pads have been removed, a 13 mm open-end spanner with a ring side that fits the diameter of the pistons exactly will work, or alternatively a tool that is as soft as possible and does not have sharp edges, for example a Tyre lever.
Matthias Borchers
Editor
