⅛ VS 3/32

When talking sprockets the term ⅛ and 3/32 refers to the thickness of the sprocket where the chain bites to the teeth. ⅛ Inch (0.125", 3.18 mm)  are used on most single-speed bikes including BMX and bicycles with internal gearing. 3/32" (0.094", 2.30 mm) chain is used on derailer equipped bicycles that have more than 3 cogs at the rear. The majority of BMX brand sprockets that you will buy for your freestyle BMX bike will be ½ inch.