How do I know what size handlebars to get my bike?

One way to determine the size and style of handlebars to put on your bike is to sit on your bike and put your hands up in the air where they feel comfortable, where you would want them to be. It can be helpful to hold a pencil or something silimar in each hand. Have someone take the general measurements such as rise, pullback (how far back the hand grip area comes toward you from the vertical rise section of the handlebar) and the angle of the grip area. If nothing else, the simple act of putting your hands in various positions may help you determine if you like the feel of certain handlebar styles (Drag Bars, Rabbit Ears, Ape Hangers etc) or not.

What is the proper way to measure bar rise?

A simple tape measure will let you determine the rise of your handlebars. There is total rise, and end rise. Total rise is the measurement from where the handlebars clamp in your risers, or mount to your top triple clamp, to the highest vertical point of the handlebars. End rise is the measurement from the handlebar clamping area to the center of the end of the tubing in the hand grip location. For accuracy, be sure to measure straight up to get this measurement, and not at an angle from the clamping surface.

What is the legal height of handlebars on a motorcycle?

The legal height of handlebars on a motorcycle depends on your local laws. In the United States it varies, with 16 states having no law whatsoever. For the other states, 20 have a limitation of 15" high handlebars, and another 10 limit the height of motorcycle handlebars to no higher than shoulder height. When in doubt, check your local laws. Or don't, and just do what you want!

What is the best handlebar width?

Handlebar width is a personal choice, and it can also be tied to visual style of the motorcycle. Wider bars tend to be associated with 'cruisers', whereas drag bars, T-Bars and rabbit ear handlebars give a more aggressive riding posture, and lend themselves well to a hard ridden, fast motorcycle. Note that wider bars can easily be cut narrower with a hacksaw or grinder with a cut-off wheel. However, you have to make sure that you have enough straight tubing in the hand grip area for your throttle and levers. Also, if the bars are dimpled for Harley style hand controls, you cannot cut them shorter as the handlebar grips and hand controls will mount at the dimpled section and be too far outbound.