What is the proper chain tension in a bike with internal hub gears? When I bought my new bike (last month) with Shimano Nexus gears I thought the chain was quite tight -- very little droop between the front and rear cogs. Now there's 3/4" drop between the cogs and I think it needs tightening.

I researched this and couldn't get a consistent answer. Sheldon Brown recommends a tight chain on a fixie but that might not apply to hub gears. Another site recommended 1/2" drop between the cogs. I've got the Shimano technical service instructions in front of me and they're silent on chain tension.

Advice gratefully received.