Abstract: A skate bike including a frame; a spring seat saddle connected to an upper part of the frame; a wheel having a central axle connected to a lower part of the frame; a pair of pedals provided on either side of the wheel; a pair of supporting shafts pivotally provided on the frame at suitable position to define a support for feet of a passenger; and an auxiliary wheel set provided on the frame at a suitable position. The skate bike is effective as an unicycle and also effective as an ice scooter or a grass scooter when used in conjunction with a pair of ski poles.