Offset Chain Ring Classic Cycle 2,5 mm (~0,1 inch) Offset cool offset chain wheel for “one piece crank”, 42 teeth For Chains of 1/2 x 1/8 Helps to bring the chain 2,5 mm (~0,1 inches) off the line not to touch the tire Diameter of the bolt circle is of standard 103 mm (~4,05 inches)