Im looking at changing my sprockets on my NSR 150 and can't decide which way to go. Im thinking 1 down on the front sprocket and 1 up on the rear, or just 1 up on the rear. I have beeen using this sprocket calculator http://web.singnet.com.sg/~ivant08/NSR150SP.htm but still cant make an informed decision. My other dilemma is, will I run a 120/80/17 tyre on the rear or a 130/80/17 ? . I use the bike primarily as a fast commuter but love to give her a workout on the weekends.