a) Drive Train - Check for Bottom Bracket wear & tear if not loose.
Crankset fully tighten including both pedal.
Check for chain wear if not change. Will stressing alot on chain.
Rider using D-link or missing link to check for loose & wear.
Jockey wheels at Rear Derailuer tighten if wore change inorder
the chain not to be derail from cassette & chainring.
Lubricate Chain, WD 40 not recommended as it will bit off the Lube
coating around the chain & bearing.
b) Control - Check brake & pads or adjustment.
Check Shifters or adjustment.
c) Parts & Tools - Spare inner tube for your wheel size.
Mini Pump with Presta or Shrader valve.
Tire lever & Allen key tools kit with chain breaker will be good.
Size 15 Spanner for rider using Internal Speed Hub at rear.
Any Additional input will be great.
Cheers,