Single speed chain tension

moved!

Why is this in "Classifieds" BTW?

You don't need a chain tensioner if you have a nutted axle. You can "walk" the axle along the fork ends by loosening one of the nuts, pushing on the rim of the wheel to move the axle, and tightening the nut back up. I learned this from Sheldon Brown's website, where you can read a more detailed explanation.

On my track bike I always just put my hand in between the wheel, downtube and seatstay area, then clench my fist to force the wheel back. It is easy to then use the other hand to cinch up the track nuts whilst keeping your hand clenched to maintain the tension.

Don't go too mad on chain tension though, it needs to be tight enough to not want to jump off, but not so tight it restricts the free running of the cranks.

It is usual that some part of the drive train, either chainrings or freewheel/sprocket aren't completely true, so you will suffer from some tighter and looser spots in the chain rotation. Adjust it to the tightest spot, other wise it will get very tight over that area of the rotation and cause rapid wear to the drivetrain.

a chain tensioner that mechanically pulls your wheel back and keeps it there is what you need. They are common on BMX's but you want one for a 10mm axle. Here is a link to one that surly do and it also has a bottle opener on it?!
http://www.wiggle.co.uk/p/cycle/7/Surly_Tuggnut_Chain_Tensioner/5360018550/