You need a box of spares as well. It’s worth keeping bits and pieces in your house so you don’t have to rush off in the middle of a job to pick them up.
- Two tubes: the right size, with the correct valve for your wheels.
- Brake blocks or pads.
- Two brake cables and a length of brake outer casing.
- Two gear cables and a length of gear outer casing.
- Ferrules (the end caps on casing) and end caps (the end caps on cables).
- Powerlinks to repair standard chains.
- Shimano chain-joining pins for Shimano chains.
- Zipties (aka cable or electrical ties). These hold the fabric of the universe together. Before them we had string. Mountain biking couldn’t exist until the ziptie was invented. Whoever invented it deserves a major international prize. No toolbox should be without a few of them.
- Electrical tape
Source : BIKE MAINTENANCE TIPS, TRICKS & TECHNIQUES