U B the expert: Do your own bike repairs
I've noticed a dramatic increase in the number of bicycle riders in my hometown this summer, many, I presume, driven to pedal by the rise in gas costs. Many of these bikes are not working properly, but need only simple adjustments to return them to peak operation. Bicycles are relatively simple machines, and anyone with a little patience can do much of the work themself and save the cost of a bicycle shop tuneup.
A couple of things anyone can do - first, inflate the tires to the proper pressure (usually printed on the side of the tire). You'll be amazed how much easier the bike will roll. You'll need a pressure guage that reads up to 110 psi, available for a few bucks in most hardware stores. Most bike have a valve that allows the tires to be filled at the gas station air pump. Lube the chain, too. A dry chain causes premature wear on bike parts, and inhibits smooth shifting. I usually pull an empty oil bottle from the trash at a gas station; there is enough oil left in the bottle to drizzle over my chain.
Many other repairs and adjustments can be made with a few simple tools such as Allen wrenches and an adjustable wrench. Don't bother with printed manuals to learn bike maintenance, though. There are a wealth of tutorials on YouTube and elsewhere that show, in detail and step by step, how to set your brakes, adjust your saddle and handlebars, fix a flat or true up a wheel. My favorite at the moment is Biketutor.com,which combines excellent camera work with a patient narrator.