1, the bike of the tightening of the screw nut should be tightened, not loose and off.
2, the rotating parts should be flexible operation, not stuck, stiff phenomenon. Such as: the front and rear wheels should be flexible rotation, and should not swing around and up and down, will be stopped when the wheel should be able to do before and after the light swing, can not suddenly stop turning. Handlebar left and right rotation should be flexible and comfortable, pedal shaft and crank should be fastened, not loose between each other, and flexible rotation.
3, variable speed gear in the variable range of the strain file is correct, variable speed position should be clear, the middle shall not have a gap.
4, the chain should be appropriate, flexible operation. Hand reverse reverse repeatedly crank crank sprocket, chain operation is flexible, no jump chain and shedding phenomenon.
5, with both hands to hold the saddle above the front and rear parts, one hand forced down the front of the saddle, saddle front end not fall. And then horizontal rotation of the saddle with both hands, the saddle should not turn.