What is the most popular choice of sprocket size on an f4I for stunting of course. Just got my first F4I and would like to do it right the first time around.

 

most f4i's ive seen have like a 55 rear and if it's not enough you can go down on the front.

 

I am -1 in front and +14 in the back. It's not streetable, but fun as hell. If you are trying to ride the streets I would go maybe -1/+5. It depends on what you are trying to do with your bike. Look at the Starboyz and Streetfighterz. They used to, and sometimes still do, rock stock sprockets. All bigger sprockets do is give you the ability to roll slower idles and offer a bit more engine braking.