Originally Posted by Easy Rider
My mistake. I didn't read the whole thread. I thought the discussion was about sprockets. You are correct that on friction drives, the diameter of the spindle determines the speed.
You're right too! It started out as a sprocket question, and somehow I ping-ponged into friction drive...my fault!
HoughMade's response says it all.
But I might suggest using whatever sprocet the kit comes with, so you don't go spending money before you even know what you like. If after engine break-in, you want more torque and willing to tade off top speed, then go bigger sprocket. If torque takes a back seat to top speed, get a smaller sprocket. But base it on what like/want from experience.