Originally Posted by
sstorkel
I think this is a spurious argument. If you've damaged your bike so much that one of your brakes is completely non-functional does it really matter than you've got to loosen two bolts so you can remove the caliper? Honestly, in that situation the fact that I can release a canti or V-brake cable in 2 seconds isn't going to change my mood: I'll likely still be miffed that my bike is damaged.
For the kinds of riding and touring I do, it doesn't make sense to try to optimize for a condition that occurs exceedingly rarely (in my experience).
If I had to release the rim brakes on my bike to compensate for a broken spoke, I'd probably say 'Damn it!' but I doubt that I'd be all the miffed. I'd deal with it by releasing some cable tension and maybe rebalancing the spokes on the wheel.
If, on the other hand, I managed to damage the rotor on a hub mounted disc, I wouldn't just say 'Damn it '. I'd probably cuss up a storm because it's not as easy to fix. Whether or not you could just loosen bolts to remove the caliper is dependent on the brakes. If the brakes are cable actuated, it's possible. If the brakes are hydraulic, it's much more problematic. You can't just take the caliper off. You have to remove the caliper, the hose and the levers. You'd probably be better off removing the rotor...if you remembered to bring the torx tool along.
And I can see lots of situations where a rotor could get damaged. The rear one is fairly safe since it has lots of stuff around it. But, for example, you could hook a rotor on something while leaning the bike up against a building. People tend to pull on stuff when it's hooked and you could easily bend the rotor a couple of millimeters. People do lots of silly things like using a $500 flyrod to get a $2 fly out of a tree.
I've trued disc brake rotors and was amazed at how little torque is required to bend the rotor. I'm not saying that hub mounted discs are inherently fragile. But they do have weaknesses...the hypertruness of the rotor being one...that you need to think about before you find yourself miles from the nearest bike shop with an unrideable bike.
Being prepared makes the difference between enjoying your vacation and spending it waiting for repairs. I, personally, know how to take remove, repair, reinstall and/or work around every part on my bike. If I can't fix it, I can McGyver my way out of it. I'm sure you have similar skills and knowledge but many people don't have those skills. Those people are the ones who should consider the issues before they go.