»There are two main types of brakes: ones that work on the rims and ones that work on discs. Rim types include cantilever, sidepull and V-brakes. There are also hydraulically operated rim brakes although they are mainly seen In Europe. Rim brakes gradually wear through the walls of the rims which is obviously not good on a touring bike. Also, for all rim brakes to be effective, the wheel still needs to be kept ‘true’, whilst wheel trueness is a non-issue with disc brakes.
»Disc types broadly fall into two subgroups, cable operated (or “actuated”) and hydraulically operated. Disc brake rotors (the disc that the caliper squeezes onto) do wear out but they are made from special steels and a rotor might last more than 50,000km. By comparison, rim brakes can render a front rim useless in 15-20,000km. Rain and mud,city riding and bigger loading make this worse.
»It is normal to classify all brakes as rim or disc acting. But it is also valid to classify them as cable or oil (hydraulic) actuated On cable systems, whether operating on rim brakes or disc rotors, as cables stretch a bit and as pads wear down a bit, the brake levers can’t travel far enough before they hit the handlebars. Adjustment need to be made at least at 500km intervals. Hydraulic systems however are self adjusting and also self centering. You don’t need to touch them until it’s time to change the pads. This varies with loads, rain, hills and speed but count on changing the pads at about 5,000km intervals.
Disc Brakes on Touring Bikes
»In about 2005, cable operated disc brakes, started to appear on long distance touring bikes. Developers took it slowly as there is a reluctance to experiment in the touring bike category. The bikes need to survive everywhere. However, cable operated rim brakes did give way to cable operated disc brakes as they just work better.
»More recently the evidence in favour of hydraulics over cable-actuated has become undeniable. Leading German and Dutch brands of touring bikes have now moved onto hydraulic disc brakes.
»Meanwhile, in the MTB world, by 2010, all but the most basic bikes had converted from cable to hydraulic disc. There were some problems 20 years ago but they have been all ironed out. Comparable performance and the lack of evidence of actual problems were clear to see. Now that confidence in hydraulics has spread to other styles and ‘disciplines’ in the cycling world.
What’s so Good About Hydraulic Disc Brakes?
»Whilst cable operated brakes have friction in them there is no friction in an oil-filled system. This is not so much an issue of energy saving. It is about ‘feel’. Modulation, or the progressive feel in your fingers, being able to directly and intuitively sense the power as the disc pads touch the rotor, is in a class of its own with hydraulic brakes. You can sense more of a connection in your hands. You get more force delivered to the pads, hence more stopping power for the same input, plus, when releasing the brakes, faster, more reliable and predictable pad retraction. Especially on long descents, this reduction or elimination of hand fatigue is very good.
»The ability to control speed is extraordinary, especially if like most cyclists you have used cable systems in the past. You can go from top speed to a standstill in a couple of seconds with a single finger on each brake lever, even on a fully-loaded touring bike. On cantilever systems for example, this is unmanageable.
»Because the hydraulic system is sealed, grit and grim cannot get in to jam up the moving bits, making them maintenance free apart from eventually replacing worn pads. This system is mechanically simpler than cable operated brakes.
»Hydraulic systems usually have opposing pads that self adjust for central alignment and also as the pads wear out. However most (except TRP Spyre) cable disk brake systems work by operating one pad only - and squeezing a rotor onto the stationary pad on the other side. This means that as the pad wears down, you typically have to wind in the moving pad (usually the outside one) to keep the right bite point. Hydraulic brakes don’t require adjustment.
»Hydraulic disc brakes are without peer once the rain starts to fall. Between wet and dry, you effectively sense no difference in the quality of braking.
»Not needing to regularly centre and adjust your brakes is a chore you do not miss.
What About Reliability and Repair on the Road?
»Hydraulic disc brakes were once seen by tourers as just another potential disaster waiting to happen. You get a leak, or a hydraulic line fails, and you’re left with zero braking power, at least on one wheel, and, if you’re outside the developed world, perhaps no chance of a repair for a few thousand k’s. The fact that most bike shops never see cases like this didn’t matter – what if it did happen?
»Contrary to common belief, disc brakes are not necessarily any more difficult to repair or maintain. Let’s say your hose gets ripped out and your mineral oil goes everywhere. Well, a spare hydraulic hose weighs next to nothing — much lighter than the mechanical brake equivalent. But, you have nothing to refill the system with — and you don’t want to lug around a bottle of mineral oil “just in case”.
»Remarkably, regardless of the stern warnings in the brake manuals, pretty much any light oil can be used. Sewing-machine oil, baby oil, or light suspension oil for motorbikes, cars, snowmobiles, all work and even water works in an emergency as long as there’s no risk of freezing. And instead of taking a full bleed kit, you’ll probably find that every developing country will sprout the kind of ingenious minds that spend their lives fixing everything that moves, and will find a way to draw your new hydraulic fluid through the system. After all, it’s just a tube with a small reservoir and a plug at each end. Get down on your knees and suck it through! (Or just bring the weightless plastic syringe with you.) Job done, panic over, on with the tour.
VWR gives a big tick to hydraulic disc brakes but there is one of the five models which can not use them. This is the Deccan. Because the Deccan uses 9 speed STI shift levers on drop bars there is no hydraulic option. The next best thing to hydraulic brakes is the TRP Spyre cable disc.TRP Spyre mechanical disc brakes are cable actuated, but benefit from a dual piston design. This means that both pistons move equally against the rotor, as opposed to the single piston design of the Avid BB7 and Shimano CX75 mechanical (cable) disc brakes. The Spyre is 20 gms lighter than the BB7, has better modulation, better clearance, easier adjustment for at least the same braking performance.