I just changed my rear from 34t to 30t with mike's sprocket. running 17/30 now with what i believe is the stock chain, as the 17/34 were both stock. I'm JUST short of bottoming out the adjusters (at smallest mark on the swingarm indicators) with the increased chain length. but there is some space. i check my bike before i ride and the axle is straight & the chain is tight & ive had no issues in the 60ish miles ive put on since the switch last week. MUCH better high-speed manners too... 1st is a scosh high for my tastes but not a big deal. & 70mph @ 3700rpms (gauge-indications only, mind) is definitely not bad! I can cruise at 75 in 5th pretty comfortably, & 55 in 4th is just about perfect.