Purchase a new front wheel with a motorized hub. The Electric Bicycle Motors website provides a list of online bicycle-motor retailers. Note the rim size of your bike's wheels (a measurement of the rim's diameter in either inches or centimeters, which should appear on the rim itself), and purchase a wheel in the same size. Look for a wheel that includes a power cable to connect it to the battery, as well as a throttle cord that installs on your handlebars. This system allows you to keep your present brakes and handlebars.
Also purchase a rechargeable battery pack, which will power your new motor. Look for a battery system designed for use with bicycle motors that incorporates the proper capability to attach to your frame or seat post. If you plan to ride in hilly areas or tow a trailer, consider a lithium-ion battery, which provides the optimum amount of power. These batteries come in various voltages; purchase a battery with the highest voltage you can afford, which will allow for the longest possible trips without recharging.
Turn your bike upside down and rest it on its seat and handlebars on the ground to remove the front wheel.
If your bike has quick-release forks (i.e., your wheel mounts to the frame via a system that does not require tools), loosen the quick-release lever. If you have caliper brakes (a pair of pads that squeeze to the rim when you apply the brakes), undo the connection between them.
If your wheel mounts to the fork with a nut-and-bolt system, use a crescent wrench or ratchet to loosen the wheel. As with a quick-release system, unclip the front brake system if necessary.
Carefully remove your wheel from the fork. Consider keeping the wheel if you think you may want to ride motorless at times.
Install your new motorized front wheel in the front fork. Depending on the mounting method for the wheel you have chosen, tighten the quick-release hub or use your crescent wrench or ratchet to tighten the nut-and-bolt system. Reattach your front brakes.
Install your battery pack. The installation method will vary, depending on the pack you have purchased; follow the manufacturer's instructions. (Most packs will mount to either the bike's frame or seat post.)
Attach the battery pack to the motor. Your new motorized wheel should have included a cord for this purpose. Using a single-plug system, the cord will not only allow the battery to power the motor but will convert the direct-current (DC) power put out by the battery into the alternating current (AC) power used by the motor.
Install the grip-throttle system from your front wheel to your handlebars. Again, the mounting method will depend on the wheel you have purchased.