Yeah, thats what I heard also. I put the 15 on last night and I was able to get it tight but the adjusters are all the way in now and I have no more adjustment left, so if the chain stretches then I am screwed. but if I go up 1 or 2 teeth in the rear I should be fine, like I said before I am afraid that there wont be enough motor to turn em over!!! What do you guys think?