Safety bicycle. A bicycle with equal or nearly equal wheels, usually about 28 inches diameter, driven by pedals connected to the rear (driving) wheel by a multiplying gear.  Since the 1930's this has been the most common type of bicycle, now simply called bicycle.  The older high-wheelers are often referred to as bone-rattlers.
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  safety bicycle
       n : bicycle that has two wheels of equal size; pedals are
           connected to the rear wheel by a multiplying gear [syn: safety
           bike]