[jrockway]

Came here to say this. Internally-geared rear hubs are great for certain mountain bikes, where derailleurs just won't work because there is too much mud. But for everyone else, a well-adjusted derailleur system will be fine. (Yes, you have to pedal forward to change gears. If you're stopped at a light, press the front brake and move the pedals forward. Or remember to downshift as you're braking.)

I've thrown a chain twice in recent memory: once when I was climbing on a chain where I disregarded the rule against breaking the chain without replacing the pin with a master pin (that you break off after driving in), and once when I was trying a new kind of lube on the chain (that worked more like glue than lube). A well-maintained derailleur system is very light and very efficient, and with a bit of practice, easy to use.

[Too]

Mud always comes up in these discussions but isn't a real problem. You can get mud, water, sand, branches, snow, grass, gravel or entire bushes into your gears and hardly notice it. Sometimes it feels like the whole forest just wants to go into your gears but in some magical way it always falls out again. The more i think about it the more amazing i think it is, the amount of punishment the powertrain takes is quite remarkable and even though the components are so small and precise they don't take much damage.

The only real problem with derailleurs in the forest is when they get hit by a rock, a think branch or the ground. Anything else that doesn't actually bend the derailleur is a non issue. In very very rare occasions something might jam the chain but no changes in the gear are going to fix that. And of course the mud will slowly wear and tear things down by grinding but that's not an issue of the actual gear but more of the cogs and chain.

[jrockway]

Ah yes, the derailleur thing sounds like the real issue that internal gearing aims to fix.