Hi well I recently installed sbp jack shaft kit onto my GIANT UPLANDER SE mountain bike. What an awesome design these are. Have been riding it most days to work around 32klm's each way. Anyway today while riding it around at 43klm's p/hr the crank arms/pedals felt like it grabbed and scared me a lot at that speed. I checked that the chain was not lose on the jack shaft kit and was not rubbing on the bike chain. No plenty of room their so I went back to pedalling the old fashion just to be safe and see if it’s all ok. Yuck not into the pedalling thing anymore but now I noticed that when pedalling it would free spin for half revolution before grabbing then working properly. I went back to riding with the motor on ok for awhile but then it did it again the crank arms/pedals moved under my feet and seemed to do it more often. When stopping I noticed I could turn the crank arms around forwards and backwards easily. So I had to start pedalling again to get home seemed ok for awhile when I tried to start the bike the pedal/crank arms would spin with the motor and that's how I rode it home my legs out to the side while the crank arms were rotating with the speed of the chain drive. When i pulled in the clutch the cranks stopped rotating. I think my crank bearing could be mashed or the freewheel bearing has gone and is probably the cause of the problem I’m not sure will have to have a look. Anyone got an idea what it could be that has caused this???