Oh, and bleeding brakes. Brake fluid is nasty stuff, and it’s a tricky operation for which more than two hands is almost essential. Right faff. And brake pads and brake fluid are the two least compatible compounds for efficiency…
Servicing forks. Oil everywhere, no matter how careful you are.
Adjusting cup and cone hubs. For this reason:
Always seem to need 3 hands, and re-fiddling as perfect becomes too tight once the wheels been clamped up.
PITA. Sealed Cartridge FTW.
Front mechs can be a right bugger, as can getting a stem absolutely straight.