my pryer has a 36 tooth, its a model that was designed for a batavus regency. i'm running it on a stock pepi delux with a 9 tooth sprocket and 16x2.5 tires. goes about 30 and for me that about as fast as id ever want to go on it. i think having a polini would def help the torque. I did run into chain clearance problems running the 9 tooth on the trike frame. so you might need a chain tensioner to lift it up a bit. excited to see your progress!