Quote Originally Posted by silversurfer View Post
Removing and replacing the gear change cable is the part that seems complicated to my feeble brain.
My foldie has a SRAM hub with internal gears and a cassette. The instructions to remove the "click box" seemed a bit intimidating, but in reality it is really simple. I suggest following the instructions for your friend's bike's hub to unhook and rehook the cable just for practice.

As for tools, make sure to bring a wrench that fits the axle nuts! (Probably a 15mm.) The internal gears means there is no quick release. For my bike, I managed to find a short stubby wrench made by Snap-On. It's the best quality while only half as long as a regular wrench.