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Chain Drive Ratio Calculator

Find the ratio of a chain and sprocket drive for a bicycle with
this Chain Drive Ratio Calculator.

Drive Sprocket Radius :
Driven Sprocket Radius :

Fill in the radius of both sprockets to calculate the total ratio.
Mechanical power travels from the Drive Sprocket to the
Driven Sprocket.


The ratio in a drive system is represented in reference to the number 1.
A ratio of 2 to 1 would be signified by 2:1.
A ratio of 1/4 to one would be signified by .25:1.

To find the total ratio, use the equation:
Ratio = (Radius of Driven Sprocket) / (Radius of Drive Sprocket)

Example: On a bicycle, the sprocket that is attached to the pedals is the
drive sprocket and is 4 inches in radius. The driven sprocket at the rear
wheel is 2 inches in radius. What is th total ratio?

Ratio = 2 / 4

Calculated out this drive has a .5:1 ratio. For every full revolution
of the pedals, the rear wheel turns 2 revolutions.