With the 13-18t combo I am 225lbs and have a top speed of 27mph on flat ground. And also with a much improved take off acceleration and hill climbing ability. You can also change the gear ratio qiuckly by changing the JS output sprocket . Usualy you can go up or down a tooth and not even need to change the chain length. A Doodlebugger with this setup will spank a stock geared one in a drag race.