The more you know how your bike works, the more you’ll know how to solve mechanical problems while on the road. Do your own maintenance and basic adjustments at home.
If you take your bike to a bike shop for anything major, ask the mechanic to show you how he/she diagnoses and troubleshoots. For this, you need a friendly and patient bike store. Keep in mind that it’s unfair to expect free repair pointers from a shop without also making purchases there.
We carry – and find very useful – an e-copy of the repair help section of the Park Tools web site. This site deals with the details of professional repair. We’ve found it essential for field repairs.
On a Greek island with no bike shop, we had to straighten a derailleur hanger that got bent on the ferry. How else would we have known how to measure so as to see we had it back within tolerance?
The contents of the repair kit you assemble depends on where you’re going and for how long. A kit for commuting should allow you to change a flat and make small adjustments.
We’ve found it works for us to keep these often-needed items in a rigid plastic box, which means the tube of glue is protected. Longer trips require more tools and spares. Sew a simple roll-up to keep less-frequently used tools organized. We like to keep the roll-up safely near the bottom of a pannier, and the plastic box more easily available.
Pictures of our repair kit items and items we take touring are on our Flickr site.
Two useful items in our kit that are harder to find are the Hypercracker tool (this page describes replacements for the original tool that is no longer manufactured) for removing the cassette, and the FiberFix Emergency Kevlar Replacement Spokes.