http://sheldonbrown.com/starting.html


Some Wrong Ways:

The Cowboy Mount is popular among cyclists who learned to ride on a bicycle that was too large for them. Indeed, this is the only way to get started on a bike that is seriously too tall for the rider. This dubious technique involves standing next to the bike, putting one foot on a pedal, then swinging the other leg over the saddle while the bicycle is in motion.

The cowboy mount places the rider's weight on the bicycle while it is leaning over at a sharp angle. This puts considerable lateral stress on the frame and the wheels. Bicycle wheels, in particular, are not designed to withstand serious sideways stresses, and this poor mounting technique is very hard on your wheels.


Correct Basic Starting Technique

Stand astride the frame, both feet on the ground. Most people get to this position by swinging a leg over the saddle, but if you have low handlebars, you can do it over the bars as well. If you have a "lady's" bike or other bike with a low frame, you may be able to lift your foot over the frame. It sometimes helps to lean the bike to the side before straddling it.

Do not try to sit on the saddle while the bike is stopped, this is not usually possible if your saddle is properly adjusted.

Rotate the pedals so that the pedal for your less skillful foot is 45 degrees forward of straight up.

Put your foot on the high pedal, then press down hard. This will simultaneously:

Let you use the pedal as a step to lift yourself high enough to get onto the saddle...and:

Apply driving force to the chain, causing the bike to pick up speed.
If you have not learned to do this, take the time to practice. It may sound difficult, but it isn't as hard as it sounds. Once you get used to it, it will become second nature. You will become a better, safer cyclist, because you will be able to bring your bicycle quickly up to a speed that allow you to ride without wobbling.