kunsei83

I have my bike on the bike stand, and I pedal it forward with my hands and after i stop pedaling, the pedal still keeps moving instead of stopping. Is this a big problem? Is it the wheel's hub that's causing this problem?

toomyus

if u hold the pedal and the whel is still moving does it stop?. if it tries to keep going something is up, something with the freewheel mech. if it stops then no worries.

Retro Grouch 

Your freewheel or cassette body is probably gunked up. The quick/dirty fix is to remove the rear wheel and set it cog-side-up on a trash can. Spray some WD40 on the interface where the freewheel spins and let it work in for a couple of minutes. When you can spin the cogs freely with your fingers, wipe down the outside and you're good to go.

torqd76

Do you have any sort of plastic chain guard between your largest gear on the cassette and the spokes? If so, that might be what is causing it. My pedals would continue to spin as you described, but it was because that plastic guard had warped and was creating friction between the cassette and spokes, therefore spinning the pedals. I just took the guard off and it works fine.

Surferbruce

sounds like your bike is trying to convert itself to a fixed gear when you're not looking.