From Envirowiki

there are a number of things that are easy to do at home that you can do to make sure your bike is safe and has a long lifetime.

[edit] some quick checks

• Check for major deformations/cracks before first use and after any crash.

• All nuts/bolts/screws need to be tight, bikes have a heavy work load and things could come loose.

• Check brakes work. They will wear fast if pressing against rusty rims (sandpaper away the rust and wear a face mask OR use a big file that will create less dust and be quicker).

• Check wheels spin. Buckles can be removed by tightening spokes in SMALL increments. The wheel rim hits the left brake pad near the reflector. So the spokes near the reflector connected to the left side of the hub must be too tight, and/or the spokes near the reflector connected to the right side of the hub must be too loose. Make only half turns of spoke nipples and check the effect. Repeat until no side-to-side buckles. (Up-to-down buckles can be more problematic to fix, but use similar logic to solve)

• Check pedals, chain moves. Very rusty chains need to have oil soaked into them for a few weeks. Apply small droplet to each circle link component and leave for a month or so for penetration.

• Check steering works, and the handlebars are on tight. Stand in front of the bike with the front wheel inbetween your legs. Try to move the handlebars against the front wheel to check for tightness.

• Check for any problems with tyres (glass/sharp objects embedded, or holes). Rotate the tyre slowly, while feeling the inside with your fingers, for small sharp things. Look at the outside of the tyre as you do this and check for any problems. Sometimes it's possible to turn the type inside out, this makes the punctures and embedded objects easier to find. After finding the sharp puncturing beast, remove it and place in bin. Don't just throw it on the ground, it could be the cause of your next puncture!
  • The myth of wall rubber deteriorating making the trye useless is consumeristic claptrap. The rubber layer on the outside wall protects the material inner lining of the tyre. The material inner lining contains all the strength of the tyre. As long as the tyre/bike is kept mostly out of direct sunlight, the material inner lining doesn't need the rubber protection. The rubber deterioration problem usually only occurs due to lack of use. Solution is to ride more often and wear the tyre out before it deteriorates.
  • Check the bead of the tyre. These are metal rings (which give the round shape to the wheel) encased in the tyre, which are on both sides of the tyre and fit into the rim of the wheel. The metal beads sometimes come out of the material lining, causing massive tube blowouts (if you have been riding your bike when this happens, you usually get some warning of a bumping feeling from the tyres. Stop riding before it blows out). Need to check the metal bead is encased in the material of the tyre ok. Small problems 1-2cms can be fixed with material fasteners. Larger "naked" beads of 5cm or more render the tyre (almost) useless. Remove both beads with stanley knife and use as insert for extra protection against puntures.

• Tubes. The tube valve needs to come out straight from the wheel. When at an angle, the rubbing with the wheel causes a puncture at the valve.

• Oil your bike regularly, as this will prevent rust, as well as make the bike run smoother, and reduce wear and tear on moving parts. of course, petroleum oil is nasty shit, and causes wars and capitalism - try using fine vegetable oil or similar. you can even use old cooking oil, as long as you filter the lumps out!
  • Or don't oil your bike. If you ride your bike most every day and keep it out of most of the rain, you won't need to oil. Chains don't last longer if you oil them. In fact the more they squeak, the more people hear you coming, the safer everyone is.