That's quite nice, but be careful: a motorized bicycle makes a very poor motorcycle or moped. A motorized bicycle's steering geometry is incorrect for a powered vehicle. The center of gravity is far too high. The brakes are a joke, there's no suspension, the electrical system doesn't exist, and it's a long way down to the pavement. Now, my experience with an ancient motorized Schwinn Racer that went to heaven last October and tried to take me along is not typical--I hope. Neither the police nor I know just what happened when I went o'er the handlebars and sailed onto the street, but at least my bike helmet saved my life. Had pulled nerves, broken collarbone and, most amusing, a broken neck vertebra. They fixed me up, but it's been a longer pull than I'd have wished.
It's possible that the bike itself failed, with the front fender brace winding itself around the front axle and thus locking the front tire. Lessons learned: wear a helmet and continue to inspect your bike for loose bolts and worn-out rivets. This last bit used to be standard operating procedure for every motorcyclist until Honda began making bikes that didn't drop parts into the street. Most mopeds are similarly quite safe, but most of these little bikes are aging. So have a look and be vigilant.