I just got my Mercier Kilo TT Track Bike ($347 shipped). I am impressed with the bike so far, but today I noticed the rear wheel wasn't quite aligned. I centered the wheel, and followed Sheldon Brown's instructions for "walking" the rear wheel to get the chain tight, but I'm not sure it's tight enough. The chain isn't sagging, and I can't slip it over the cog or chainring, but I can't tell if it's tight enough. Any suggestions beside Sheldon's other tip of loosening the stack bolts? Thanks in advance.