fixing wheels

Hi All!
I am a newbie in the field of robotics. I want to know what is the best way to fix wheels (say the wheels of a toy car) to the shaft of any dc motor or a servo, so that later you can again dismantle it if you want.
Using an adhesive, it becomes difficult to get the wheel off the shaft once it is fixed. Also, if the adhesive isn't good enough, the shaft wouldn't hold the wheel properly.
Lalit

Its best to use a wheel hub that has a set-screw for fastening the wheel to the shaft, another option is to use a cotter pin inwhich you have to drill a small hole thru the shaft.