Many people have found with the stock gearing of 45/14 that 1st gear is too short, and that gearing a little it taller allows the rider to use the torque in 1st gear a bit more effectively. I personally run 15/44 and am very happy with it! Once I get a bit more power out of the 250 I wouldn't mind going to 15/43, but I won't go any steeper than that. One thing I definitely wouldn't do is gear any shorter than 45/14, or you'll pretty much make 1st gear a crawler gear, or redline at 5mph. Pretty much useless for everyday riding. There is a guy on here who does a lot of touring on his bike, who runs 15/39, but I can't imagine how much the acceleration would suffer with that...