I'm reposting my response to a similar question over on the Crazyguyonabike Forum since I'm feeling lazy!...
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I run both rim and disc brakes [Avid BB7s]. I wouldn't want disc brakes on a go anywhere touring bike.
Some things to think about:
- can you get spare parts for disc brakes as easily as v-brakes?
- disc brakes add more dish to your wheels [you now would have a dished front wheel]
- disc brakes pads can wear out quite quickly in gritty conditions
- v-brakes provide loads of stopping power [can you skid wheels or endo with v-brakes?..I can.]
- disc rotors are easy to damage in transit
- are expedition tourists on your site finding rims are wearing out particularly fast?
- disc brakes can overheat as well at similar temperature ranges as rim brakes
- v-brakes take seconds to adjust and don't require much attention
- disc brakes complicate rack mounting
- discs are heavier and more expensive
- disc brakes require special hubs [how easy will they be to find on the road overseas?]
- large disc rotors can create so much braking force on sticky [paved] roads you can damage the fork/frame
- disc brakes will require a fork that can handle the forces involved and may compromise the comfort of the bike: look at the Safari, Big Dummy, Karate Monkey forks [all designed for disc brakes] compared to the LHT, REI Randonee, Thorn, Trek 520 forks [all designed for rim brakes].
I am a techy person and when disc brakes first came out I was sure they'd be better than v-brakes. After years of using both I'd prefer to use v-brakes on my touring bikes.
I haven't been overly impressed with disc brakes when touring on wet muddy roads and the fast pad wear is a real problem under these conditions if you can't get spares.
Not all rims are made equal - if wearing out rims is an issue you need to purchase rims that have a thicker and/or more durable braking surface.
A quick survey of touring bike manufacturers:
- Surly - they love discs, but don't spec them on the LHT
- Trek 520 - no discs
- Bruce Gordon - no discs
- Thorn - no discs
- Koga-Miyata - no discs
- Cannondale - no discs
- Rocky Mtn Sherpa - no discs
On Eric Parsons recent Lost Coast Tour he and his partner had to ride brakeless as the pads wore out so fast on their Avid BB7s due to the wet gritty conditions.
Just so I don't sound like a disc hater I have 3 sets of Avid BB7s in service and I have toured on two different disc equipped bikes. If I was commuting in the PNW or in a Canadian winter I'd spec a bike with discs.
safe riding,
Vik
www.thelazyrando.com