Brakes for cycle touring – a very personal viewpoint...
It is easy for us to spend most of our time on worrying about how fast a bike will climb, what average speed we can manage or the rolling resistance of tyres. But in reality how quickly and easily we can stop a bike is more important. As cycletourists, often riding heavily loaded bikes on steep roads, this becomes an even higher priority. The one snag is that though brakes are now more effective than ever before also now come in a bewildering variety so hopefully this article will help you make a more educated choice for your own use.
Firstly lets look at the three main types of brake currently in use – rim brakes, hub brakes and discs.
These rely on a principle almost as old as the wheel itself. Essentially they consist of a mechanism that forces a friction pad (originally leather, then rubber and now synthetic) against the rim of the wheel. Though this sounds incredibly crude it's the system that has stopped perhaps 99% or bikes for the last 150 years and so they must be at least adequate. There are three main types – those that are attached to the fork-crown and seat-stay bridge and via a calliper 'pinch' the pads onto the rim. It is this system that is used by almost every road-racing bike ever made and with good reason – light, simple, reliable and effective. But for our purposes – those of the touring cyclist – they have one drawback; if you have fatter tyres and mudguards (as we do) then in order to give enough clearance the calliper has to be longer and so loses mechanical advantage and a great deal of stiffness as they are only attached by one central bolt. You end up with spongy brakes that are not overly powerful. There have been variations on the theme whereby the callipers have their pivots brazed onto the frame, but by then you are getting a heavier and more bulky brake that still can't match the stopping power of the alternatives. For that reason we can discount calliper brakes for serious touring bikes.
The alternatives are cantilevers and 'V-Brakes'. The former are very simple – just levers on either side of a fork/stay that when pulled up by a wire force the pad onto the rim. How long those levers are dictate the mechanical advantage – i.e. short levers will give less braking power but a firmer lever.
The second are the now more popular 'V-Brakes' introduced by Shimano. These are little more than very long cantilever arms which offer even greater mechanical advantage at the cost of needing to pull more cable (and so cantilever and V-brakes need special, and incompatible brake levers). Both types use the same brazed-on pivots on the forks or stays and can be immensely powerful. The one snag with V-brakes is that even the longest 'arms' limit the clearance available to tyres and mudguards so for those needing the maximum clearance cantilevers are a better bet, however as the two are similar and largely interchangeable (brake levers apart) I'll treat them as a single type.
Hub or 'Drum' Brakes
These have been around for a very long time and so, as with rim-brakes, they must have something going for them. They work like a car's drum brakes (now seen only on the back of cars if at all) in that the hub forms a drum, and pads (or shoes) inside the drum are forced against the drum inner-surface by your brake cable. I'll not spend much time on these as they have one major Achillies Heels - if you damage a rim you will need to find a wheelbuilder to replace it (and he may well not have the correct lenght spokes) - no bike shop will have a replacement wheel 'on-the-shelf. They are also less suitable for loaded touring in mountainous areas as they can suffer from 'fade' – on a long downhill the drum quickly heats up and expands to the point where the shoes have to move more and more to make contact and eventually cannot put any pressure on the drum – i.e. no brakes! They do have some good points, and their lack of maintenence needs, and the fact that the internals are protected from knocks make them great as a commutor choice, but for touring discs are better in almost every other respect so we'll move on to them.
If your purpose is to stop a bike come rain or shine then discs are the way to go. First developed to stop aircraft on landing, then cars they work brilliantly on a bike. Instead of the brake pad being pressed onto the wheel rim, it is forced to clamp a separate steel disc attached to the wheel hub. It's a pretty simple system and once you've used good discs it's hard to go back. If that were all that mattered then this article would be over, as it is things aren't quite so simple so lets look at the pros and cons of V/cantilever brakes vs discs purely from the touring cyclist's point of view...
In the dry decent cantilevers/V-brakes will lock either wheel with relative ease, therefore there is plenty of power. In fact in this respect they are at least as good as discs with the proviso that disc brakes seem to be less prone to lock-up and are easier to modulate. In the wet, modern V-brake blocks have very good performance, but discs are even better and more consistent even if the rim has been plastered in road grime. A clear win for discs.
A rout for discs – they simply don't wear out the rims. On a bike using rim brakes the pad compound will gradually wear away the alloy of the rims especially if the pad picks up grit (it will) – to the point where the rim will become so thin it will fail. Personally I think that when a wheel has got to this stage it's probably time to replace the wheel for other reasons – spoke breakages, fatigue around the rim's spoke drillings, hub wear etc but the advantage remains. A knock-on advantage is that with discs you can use a lighter rim as you don't need to take into account the rim weakening as it becomes thinner, nor do you need a machined rim surface.
One look at a disc brake set-up and it's obvious that there's a lot more metal there than on a pair of cantilevers – in the grand scheme of things it's not a massive amount but it's there nevertheless. Advantage rim-brakes.
Once set up (a little fiddly) a disc brake needs no more adjustment than occasionally pulling through a little more cable (as with any brake). Pad changing involves dropping out the wheel, flipping out the pads (they are held by magnets) and slotting the new ones in. It's a lot less hassle than trying to line-up V-brake pads and of course V-brakes wear pads unevenly so you have to adjust their position as they wear. It's not arduous, but a faff that needs doing every week on tour. So again a clear win for discs but with two provisos. The first is that as the discs are at the hub they require much longer cables and cable-runs. As the drag in a cable is greater the longer the cable is, and that drag can only increase as the cables lose grease and allow water ingress, the lovely feel of discs will deteriorate faster than with cantilevers and V-brakes where the front cable in particular is very short. The second and potentially more important disadvantage is that a V-brake or cantilever will take any cheapo pad picked up in the third-world or your local supermarket – they might not be brilliant but they'll work. The disc brake requires specific pads and there are many incompatible designs out there. This means that on tour anywhere remote (like rural France...) you need to carry all the spares you might need. Luckily they are light but don't forget...
Personally I'd call that a score draw;-)
Both systems rely on cables and so no advantage there and in both the basic mechanism is pretty simple though the rim brakes are VERY simple. The one problem that I've discovered with discs is that the discs themselves are prone to being bent in accidents or by clumsy handling (bike racks being a prime culpret). Once bent the disc has 'stretched' and is almost impossible to straighten – you can make it better by levering it back in the jaws of a big adjustable spanner but it'll always rub a little. More irritating than mission-critical, but a disadvantage. On the other hand rim brakes need a straight rim, and though generally a touring cyclist will be able to straighten a rim, some damage, especially the sort of flat-spot you get after hitting a big pot-hole can make braking very uneven. But to balance that, with discs a damaged wheel needs to be replaced with a disc specific wheel, and though those are common in most developed countries you will not find them in the wilds – so a broken wheel may cost you ½ your braking...
Rim brakes just edge this one...
So what's left? Disc brakes put more bending force through the bottom of your forks and so in theory you need heavier forks – the brazed of fitting will also stiffen the bottom of the fork, so again a bit more weight and a marginal affect on ride quality. The actual structure of a disc-brake, especially at the rear, can cause problems with certain racks and/or panniers – so something you need to be aware of. Lastly friction develops heat and on a long mountain decent a rim brake can heat to the point where it can melt an inner-tube. Primarily a consideration only for those coming off 2000m cols or hurtling down steep hills on a tandem it's still a clear win for discs.
Hydraulic or cable-runs
Both types of brake are available as hydraulic versions, and the advantages are considerable. With no friction the braking is so much smoother (and stays that way unlike cables) and easier to control. In particular a quality hydraulic disc set-up will be a revelation for someone coming from a cantilever set-up and are the best brakes currently available. The big snag is that you are unlikely to find spares or be able to do roadside repairs. Though they are magnificent I'd personally feel uneasy about taking them too far from civilisation. Given that the alternatives are more than adequate I personally wouldn't use hydraulic brakes far from home.
So which should you choose?
I think you need to think very carefully what you want to do with your bike, both now and in the future, as a shift from discs to cantilevers is difficult and expensive. Ultimately it comes down to two things. If you want the very best and most consistent braking, rain or shine, then discs hold a distinct advantage. If you want something light, simple, rugged and with easy spares availability and which work just fine then either V-brakes or cantilevers hold an edge. Of course we want the best of both worlds, but as each has advantages it's as so often in cycling, a question of the best compromise. For my own use? If I were to set out tomorrow to cycle round the world, or to choose a bike design for a group of 10 cyclists cycling round France I'd probably stick with my V-brakes. If I was cycling solo in Europe, and especially in areas where braking is critical like the Pyrenees, then I'd probably go for discs. Only you can decide which is for you.
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