More than 30-35mm of slack on the upper run on the center stand and my bike vibrates noticeably more, and has more lash in the drivetrain. When adjusted properly, between 20-30mm slack, it shifts, pulls and revs cleanly and vibes are pleasant, with no drivetrain lash. Also better mileage. Just saying what worked on my bike. With the variability in these, YMMV. I could acquire the 100 link chain in a day or less from my local shop, inexpensively. since my bike is transportation, not just recreation, I prefer not to be down for a week or two waiting for mail order parts I can source here. The 102 did not work. Could practically pull the chain completely off the sprocket with the snails all the way out. The 101 started life with the snails more than half the way out, so it seemed pretty likely the 100 would work. It did, and has settled in nicely over the 170 mile ride I did yesterday.