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How easy is it to keep a mechanical (non-hydraulic) disc brake system working at home with a set of "normal" (not bike-specific) tools, especially compared to rim brakes?

Discs seem to be currently en vogue in adventure biking (cf. the Salsa Vaya) and even in cyclocross bikes (cf. the Merida Cyclo Cross 300). Despite their all-weather stopping power, I have heard several people (even people working at LBSs) say that they are a lot of work to adjust. How true are these claims?

Can a layperson reasonably expect to keep them working optimally without the help of a LBS, or do they entail regular professional "servicing"?

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    If you keep a set of rim brakes working well, and have access to google/utube, you can easily keep cable disc brakes working optimally with the same tools you already have. Only caveat - discs have finder tolerances, and require more care with respect to oil contaminating the pads. If you are a messy 'gorilla with a spanner' mechanic, you may find rims better.
    – mattnz
    Commented Jan 31, 2016 at 23:20

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There's two different situations here.

The first time disks are set up after installation can be a lot of work. The calipers need to be fixed in the right position, which can involve a special tool to shave a little off the mounts to get them square and parallel to each other, then some precise setting of the mounting adapters and positioning of the caliper on them. Both can be tedious because you need to do the bolts up quite tightly without letting the thing you're attaching move. If you're unlucky you might even need to bleed hydraulic brakes.

But once that's done it almost never needs to be changed. So "setting up the brakes" means changing brake pads and every year or so either replacing the brake cable and outer, or bleeding the brakes. Neither of those should take more than half an hour, but I'd probably still get a shop to bleed the brakes because it's messy and toxic.

Just changing pads is normally quick, even if you have to turn the bike upside down to pull a wheel out. It's usually ~2 minutes plus the wheel removal Cleaning the rotor takes as long as swapping the pads. Mostly it's just a dirty job. I wear disposable nitrile gloves and just use toilet paper to clean the rotor, but somehow still manage to get road dirt off the caliper on myself every time.

IMO the difference in braking power would make up for any difference in hassle, but I've also found that to keep V brakes working properly takes more work than keeping discs working. Setting V brake pads up is a bit of a pain, and they wear out fast compared to disk pads. But you have to redo the V brake setup every time you change pads, where discs you just push the pads out (hydros) or wind the adjuster screws out (cable). It's quick and low-hassle.

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    And if you know tricks. Setting up discs are easy. With as many bikes as I own and as many tools as I own (have more than most LBS's) I still do not own a brake tab facer. All disc brakes are now post mount and come with an IS adapter, rendering the tab facer unecessary. Even if your IS tabs are not parallel, it doesn't matter - corrected via the adjustment in the adapter.
    – Brady
    Commented Feb 3, 2016 at 20:15
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Disc brakes - to me - are easier to maintain than rim brakes. Rim brakes take a lot of adjustments as you wear the pads. The pads on rim brakes have to be given more and more toe-in adjustment as you wear the pads to keep them working optimally. Disc brakes are far less tedious. I will not buy a bike that I am going to ride a lot with rim brakes. Six of my seven bikes are all disk, the only one that isn't is my dirt-jumping/bmx bike.

Mechanical disk brakes only require minor adjustment when the pads wear down because only one of the pads actually moves in a mechanical disk brake, the outer pad moves in and presses against the rotor and against the opposite pad. So as the inner pad wears you have to adjust it closer to the rotor, typically with a 5mm key wrench. Hydro's don't have this as both pads move.

If you consider the all-weather performance, longevity of disk pads, no rim wear, and cleaner upkeep (no rim black dust from pads). Disc brakes are a no-brainer.

My most recent bike, a Jake the Snake Cyclocross bike, has mechanical disks but eventually I will put hydros on it later as an upgrade.

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  • Disc brakes are more expensive to maintain, but they need less tweeking too, so IMHO.. it is a wash. When they do fail though... They usually fail engaged or jammed--showstoppers. This makes them unsuitable for some situations.... However, you cannot beat a disc brake in the snow and ice! So, they are ideal for other situations....
    – david1024
    Commented Jan 31, 2016 at 15:42
  • I just talked with a guy from yet another LBS yesterday and he in fact told me that he tries to steer customers away from (mechanical) disc brakes because for 90% of scenarios a good rim brake will be nearly as good at stopping and is serviceable in pretty much any corner of the globe, whereas not all LBSs are capable of dealing with discs. On the other hand, the touring bikes he sells are from Fuji, with no disc brakes: Does he stock them because he doesn't like discs, or does he not like discs because he doesn't stock them?
    – errantlinguist
    Commented Feb 3, 2016 at 15:01
  • Everyone has opinions. But my 23 years of riding, racing, building bikes, and traveling the globe says different :-D
    – Brady
    Commented Feb 3, 2016 at 20:09
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If you are going to service them on the go you'll need to learn how. When you get new set of brakes, tear them apart and put them together a few times. It may take an hour or three, but then you'll know how to fix them.

Which is better is really up to your use case. Both will stop your bike when necessary.

My list of issues to consider:

  • Replacing a disc is easier than replacing a rim.
  • Bent disc is usually easier to fix than loose spoke while on the road.
  • There are 100s of incompatible disc pads while there are only a few different rim pads.

Every mechanical disc brake and rim brake set I know of can be serviced with a typical multitool with torx heads.

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I will try and stick to your specific questions. To adjust either type at home is possible, neither is more difficult but have different techniques. On that basis I would say to choose freely, and learn how to maintain the one you own with a good how-to book or online videos etc.

Disc brakes do not stop you any faster in the dry, but do potentially help you stop faster in the wet, as the braking surface does not go through puddles and mud.

Personally I think that cable disc brakes are easy to maintain once you know how. You need the disc to be straight and true, then install the caliper so that the pads centre around the disc. You can adjust the 'fixed' pad with a 5mm Allen key and the 'floating' pad with the tension in the cable. The floating pad is the one outboard which is moved by the cable. On mechanical disc brakes, only one pad is moved by the cable. As the pads wear down you can adjust both sides to move the pads closer to the disc once more. Pads might be more expensive but you might judge them worth the expense. If you're concerned about being far from home in need of pads, take spares along with you.

Rim brakes are also possible to maintain at home with the same tools, the pads need to be installed carefully to line up with the rim and not touching the tyres. Also to keep them quiet, they should be toed-in. Then you set the cable tension with an Allen key to make the pad spacing correct each side of the rim. Small screws on each brake arm allow you set the spring-back of each arm individually. Then the brake will spring open again correctly. Fine adjustment of rim pads can be fiddly, but you can learn in the warm and practise.

Now, neither type requires much in the way of specialist tools, except for further maintenance like keeping the rim straight (true) or keeping the disc rotor straight.

So Yes a layperson can maintain either style of mechanical (cable-operated) brakes.

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