11 and the front wheel support frame 13 supported to pivot about the swing shaft 13 39 mounted on the swing frame 11 therefore as shown in fig6 when the vehicle is about to turn a curve or corner the front wheel support frame 13 and the front wheels 14 are pivoted along the tracks when swing frame 11 swings under the body 6 however the position of the rear wheels 10 mounted on the rear axle 9 does not change with respect to the body frame therefore the body frame is guided by the swing frame 11 and the front wheel support frame 13 along the curve such that the body frame is slightly misaligned with respect to the travel direction the front wheels 10 and the rear wheels 14 and the guide rollers 20 and 23 will not separate from the rails 2 when the vehicle travels along a sharp curve thereby providing very smooth and comfortable travel furthermore since the rear axle 9 is held at a given position relative to the body frame a complex transmission mechanism need not be used to transmit power from the pedals to the rear wheels 10 through the chain 48 of each pedal mechanism as a result a simple light weight power transmission mechanism can be used in addition to this advantage the four wheel vehicle described above can travel along a sharp curve so that a sophisticated track effectively using a compact area of an amusement park can be obtained wherein various types of up and down inclines and cants can be provided to enjoy 34 sky cycling 34 the front end of the swing frame 11 pivotally mounted at the middle portion of the front wheel support frame 13 substantially passes.