If biking hurts your knees, your bike is probably the wrong size / needs to be adjusted. Your legs might be bowed outward too much, your feet may be turned in or out (putting pressure on the knee while slightly twisted, bad news), your seat might be too low, etc. Running around with your knees bent almost 90 deg. will make them ache very quickly, riding a bike too small for you is very similar.
(You may also be riding in too high a gear. Spinning in a fairly high RPM is best, fighting against a heavy gear is hard on the knees.)
Any bike shop worth its lingering rubber smell should be able to help you find a bike that fits like a glove. If you don't enjoy cycling, that's one thing, but don't write it off just because you tried it on the wrong bike. Running in shoes three sizes too small probably wouldn't be any fun either. :)
(You may also be riding in too high a gear. Spinning in a fairly high RPM is best, fighting against a heavy gear is hard on the knees.)
Any bike shop worth its lingering rubber smell should be able to help you find a bike that fits like a glove. If you don't enjoy cycling, that's one thing, but don't write it off just because you tried it on the wrong bike. Running in shoes three sizes too small probably wouldn't be any fun either. :)