Maintenance & Repair

Maintenance
Bicycles are hardy machines and need little maintenance to keep them running smoothly. There are a few things, however, which need periodic attention.
Tire Pressure
Virtually the only element of a bike which requires frequent action is tire pressure, since the tube will slowly lose air whether you ride or not. To keep your ride as smooth and effortless as possible, you really should keep the tires at somewhere close to the recommended pressure. If you don't, you will really notice the reduction in performance. The recommended pressure can usually be found embossed on the side of the tire itself. Of course, be sure not to exceed the recommended maximum pressure or you could blow out your tube. Once a week is a good timetable for refilling tires. You should have a decent floor pump with a pressure guage. Presta and Schrader Valves All you need to do is remove the valve stem cap, attach the nozzle and and pump the tire until the needle reaches the right number. Then simply replace the cap and ride.
     You should know, however, that there are two different kinds of valves - Presta and Schrader. Schrader valves are thicker and require only the removal of the stem cap. Presta are taller and thinner, and once the stem cap is off, the top of the valve itself must be loosened by screwing counterclockwise. Only then can a pump be used to fill the tube. After filling, the valve top must be screwed down again and the cap replaced. Newer pumps usually work for both kinds of valves, but older pumps may not. Make sure your pump is the appropriate type for your valve or it can completely deflate your tube.
Bicycle chain Chain Cleaning and Lubrication
The other component which deserves some regular maintenance is your chain. The chain is the drive train for your bicycle, turning the sprockets which turn the wheels - if it doesn't go, you won't go. Removing the grime and lubricating the moving parts keeps wear on key parts to a minimum and lets you go faster. There is considerable disagreement on the proper way to maintain a chain, and it varies from "knock the gunk off of it when it looks too dirty," to "remove the chain every two weeks, soak it in kerosene, let it dry for two days, soak it in hot wax for a day and put it back on." There seems not to be much hard evidence to support either position. Here's a compromise chain cleaning process which seems reasonable and not too onerous.
Batteries
If you ride at night or dusk or chance getting caught in poor light, you should have front and rear lights to be visable to traffic. Lights require batteries and batteries wear down, even when they are not being used. Check the lights occasionally to make sure they are as bright as they should be. Cyclocomputers use batteries as well, but you'll know when they're dead, because your readout will disappear.
Tuneups
Beyond the simple steps I have covered, maintenance begins to get a little more complicated and requires some technical knowledge and occasionally some specific bike tools. While it's not difficult and you could probably do it all yourself, you might not care to right away. In this case you should let your local bike shop tune your bike up once a year. This involves checking out the mechanics, tightening brakes and shifting cables, adjusting the chain and making recommendations for specific repairs when needed. Get your tuneup appointment early, as it may take as long as a month in the busy season. If you choose to do your own tuneup, here's a checklist from Bicycling.com.
      As you get more riding experience you will probably want to take on more of the wrenching yourself. See Resources for links to many sites which can help you.
Repair
Flat Tires
By far the most common problem for cyclists is the flat tire. Usually this is caused by a small sharp object in the roadway, such as a grain of glass or a screw, which penetrates the tire and holes the inner tube. Some flats, characterized by two small holes side by side (resembling a snakebite), are called "pinch flats" and are usually caused by a combination of underinflated tires and an impact, such as hitting a pothole or riding over a curb. While a flat is certainly cause for pulling of hair and gnashing of teeth, it can be quickly and easily fixed. Here's how to repair a flat. It's worthwhile to go through all the steps of changing a tire at home before you hit the road.
      One thing you can do to reduce the possibility of flats is inspect your tires after each ride - even during a ride if you ride over a rough spot. Make sure thare are no small stones, bits of glass or metal or other foreign objects embedded in the tread. These could work their way inward through the tire and puncture the tube, so remove any that you find immediately.
     Apart from flats, problems occur infrequently and, when they do, need a little more technical knowledge to address. Again, the Resources section has links to sites which will show you how to repair any problem that arises. Or you can call on your local bike shop again.
Riding Tool Kit
There are a few tools you should take with you when you ride. These will allow you to make simple repairs on 95% of the problems you're likely to face. Problems really do not occur often, so one tool kit among a group of riders should be sufficient (make sure you have a spare tube for each size tire in your group). If you're going to tour, ride at an advanced level or want to do your own wrenching, you'll probably want a few more goodies - you'll know what these are when the time comes and as you learn more about mechanics. A small tool kit can be easily packed into a seat or handlebar bag.
Home Tool Kit
If you're not going to do much of your own work, the riding tool kit will be most of what you need, but there are some additions which will make it much easier.
Floor Pump  You'll definitely want a decent floor pump, since this is much easier to use than a mini pump or frame pump and you'll be using it a lot. Make sure it has a pressure gauge.
Spoke Wrench   Park Wrench and Delta Spokey You can adjust your spokes with this when they start making music as you ride. You'll have a devil of a time determining which size you need - ask your local bike shop (you'll need to take in the wheel). A Park spoke wrench or a Delta Spokey are inexpensive and very adequate. Don't get a round multi-size wrench - these are usually inferior in quality and can round the edges of your spoke nipples. I used to take a spoke wrench riding and adjust my spokes on the fly, but I threw the wheel out of true, so now I do it at home where I can be more careful. Know what you're doing before using this tool too liberally.
Full Tool Kit   If you find the Beginner's Tool Kit Allen wrenches on the mini tool a little awkward to use, as I do (and Allen wrenches are needed to make practically any adjustment on the bike), you can buy a set which is easier to use Bike Repair Stand at any local or on-line bike retailer. There are also many kits of varying size and quality with a more complete set of tools you can buy if you want to try your hand at advanced wrenching. Don't worry if the kits seem a bit too comprehensive at first - you'll grow into them! Bicycle repair and maintenance seems to be a world unto itself among bikers, and a surprising number go as far as building their own bikes from the ground up!
Bike Stand  This is basically a big tripod with a gripping arm to hold your bike off the floor while you work on it. They're not cheap, and you can always rig something with bungee cords or 2x4s, but they do make it easier.