DRIVE-TRAIN
Clean
Complete drive-train service (inspect, repair, adjust: cables, bottom bracket, crank-set, derailleurs)
Replace chain (may need to replace cassette, too)
Replace cassette
Replace chain-ring(s)
Replace crank-set and bottom bracket
Adjust front derailleur
Adjust rear derailleur
Replace front derailleur
Replace rear derailleur
Install new derailleurs and shifters
Replace shift cable(s)
Derailleur hanger (frame) repair/replacement
Remove pedals
Install pedals
Overhaul pedal bearings