Originally Posted by
PepeM
I recommend
this one. Incredibly small and has the basics. I'm sure someone will recommend something with spoke wrenches and chain breakers and torx keys and everything, but most bike related things can be solved with a few allens, which is what that one has.
I think it varies.. some basic things like my stem's bar clamp, brake pads and seatpost clamp all adjust with a torx T25. YMMV