Step 1: Parts & Supplies!!
•40, 41, or 50 SAE chain size
• Bike (preferably with sliding dropouts)
•PBI Aluminum sprocket
•3.5" 6061 solid aluminum or
•Hob sprocket cutter
•20 T rear steel sprocket as a pattern
•General shop tools and knowhow
Tree Fort Bikes has a rear steel sprocket
♦You will need a large front sprocket and a small rear sprocket for this conversion. Ideally you want aluminum because it is stronger per weight than steel which means that is is light!! PBI sprockets has blank aluminum motorcycle sprockets that we can use for this project. I suggest using a 32 T front and a 20 T rear; this gives a 1:1.6 gear ratio which is perfect for mountain biking.
♦Since PBI doesn't carry 20 T sprockets and we especially need one that is internally-splined, we must machine our own.