Sheldon Brown on Brakes for touring bikes...

David Cambon posted this Adventure Cycling article written by Sheldon Brown about the different brakes that touring cyclists may be considering.

There are a few points I'll add to what Sheldon says:

Cantilever/V-brakes:

• Cane Creek now makes a drop bar v-brake lever which is very nice.
• I've used the Dia Compe 287-V and it has worked nicely for me.
• I've not had any clearance issues with v-brakes fenders and 26 x 2.0" tires
• pads for these types of brakes are very common, especially if you don't use the cartridge style v-brake pads
• I'd recommend using a Koolstop salmon coloured pad for great performance wet and dry
• Although some folks are worried about rim wear unless you tour exclusively somewhere wet and gritty tourists are not having issues with worn out rims, David Cambon suggests a properly hand built wheel should last 30,000kms on a touring bike - YMMV.
  
• I've never had issues with rim brakes overheating. If you can use pulse braking, sit up to catch the wind and let your bike run or take a break to snap a photo while your rims cool. Interestingly disc brakes can overheat as well and although they don't blow a tire if your discs suddenly stopped working or applied full braking force without notice - you wouldn't be any happier than a blown tire.

Disc Brakes:

• You need a very strong stiff fork for a disc brake. This means you'll be giving upthe comfort of the classic curved steel touring fork that bike builders have been perfecting for a long time.
• My experience with disc brakes [Avid BB7s] on the Dempster Highway has made me question the performance of discs in wet/gritty conditions. My brakes worked, but they were certainly significantly impacted by the mud and rain I was riding through. true the caliper and disc are not near the hub, but enough crap splashed up into the hub area that braking force was reduced, pad wear was accelerated and I had to adjust the pads a lot to get clearance for the rotor as crud built up.
• Finding disc pads that fit your brake will not be as easy as v-brake pads so carry a couple extra pairs on tour. If you tour is long and you'll be traveling through less developed countries you have to ask yourself if you'll be able to get spares you need to keep your brakes working.
• I'd stick with mechanical discs on a touring bike for simplicity and ease of repair. With Avid BB7s if the front caliper fails you can quickly remove it and install the rear brake on the fork to get to the next town and get it replaced. If a cable brakes it is an easy field repair to replace it with minimal tools.
  
• One popular myth is that disc brakes don't overheat so they would be ideal for a heavily loaded touring bike in the mountains. Logically an engineer can surmise that disc brakes are not immune to over heating [the heat has to go somewhere and there is not much mass in a rotor or caliper to absorb it, some heat will be dissipated to the air, but there is a finite rate at which that can happen which you can exceed with heavy consistent braking] and the tests run by a German mountain bike magazine confirm this. When disc brakes do overheat the brake can stop working or can seize up - neither is a good thing on a touring bike in the mtns so you need to manage your heat load with discs as well. If you need further proof that discs can overheat just head to a tandem site and note that nobody will approve a disc brake as a third drag brake on a tandem [unlike drum brakes which work well in this role] - this is simply because they'll overheat and fail if sustained braking is attempted.
• Disc brakes apply a lot of force to a wheel in an asymmetric fashion which will eventually cause spoke failures.
• Disc rotors are delicate and can easily be damaged [flying, buses, taxis, trains] so you have to ask yourself do you want to be pulling the rotors when you need to transport your touring bike?
• I find modulation of Avid BB7s to be similar to a v-brake.
  
• A normal sized rotor [160mm] provides the same braking force as a good set of v-brakes. This is enough to skid a rear wheel or do an endo on an unladen bike. Keep in mind there is no more braking force to be had after this. If you were to add a large 203mm rotor to your bike in the hopes of even more braking power keep in mind under most conditions you'd simply reach the same point of skidding a wheel or doing and endo. If you were on a heavily loaded touring bike and happened to be on some sticky pavement you would be able to generate more braking force than a v-brake or standard disc, but keep in mind all that force has to be transmitted through your front wheel, fork and frame - it wouldn't be hard to damage your bike permanently if you got too aggressive under very high traction conditions.
• this is not to say you cannot or should not use disc brakes on a touring bike, but they are not a magic bullet and they come with trade offs, but if you mostly were a bike commuter in the PNW and wanted to use the same bike for touring discs would make sense. If you wanted to tour on a MTB with a suspension fork discs may be your only option with many forks. If your touring bike was also your winter commuter discs definitely make sense in the snow/ice.

At the moment I have one touring bike with v-brakes and one touring bike with Avid BB7s. Although I think v-brakes make more sense for a touring bike I continue to use a set of discs and will modify my opinion if my experiences and/or the touring journals I read demonstrate they are a better choice.