there's also the fact that as the suspension compresses the chain is tightened
here's an extract I've found via Google, I usually run about an inch with unloaded suspension, or thereabouts
A new, too-tight chain can, in no time at all, turn into history. The best way to check chain tension, the one used by many race teams, is too ask two of your biggest friends to sit on the bike and compress the rear suspension to the point where the wheel spindle, swing-arm bearing bolt and the front chain-sprocket centerline are all in line. That is the point of maximum chain tension. Or you can compress the bike's rear end with a ratcheting tie down. Free up and down movement at the middle of the chain's bottom run should be about half an inch (13 mm) with the suspension compressed.
