I have 15 year old twin nephews that live a few hours away, so it is not possible for me to maintain their bikes. If there is a problem, they must wait until their mom feels that she can afford to take the bike to a shop for repairs. The problem of the moment is a simple broken derailleur cable. A $5 part and a few minutes to install and adjust, but the bike has been out of commission for weeks.

One of the boys has fairly decent mechanical skills and could probably figure it out with a little aid. It's really hard to tell someone what to do over the phone, however. Can anyone recommend a good maintenance book for a beginner? I'm talking basic stuff like fixing flats, adjusting brakes, replacing cables.