I think the rule of thumb for driveline efficiency these days is: big chainring - everything except biggest two sprockets.
Or you can read about testing this in detail: http://www.bikeradar.com/us/road/gear/article/friction-facts-free-speed-from-proper-shifting-44016/
I wouldn't put my thumb in there, but whatevs.
I'm always sticking my digits where they don't belong.
@Scilly.Suffolk started
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I think the rule of thumb for driveline efficiency these days is: big chainring - everything except biggest two sprockets.
Or you can read about testing this in detail: http://www.bikeradar.com/us/road/gear/article/friction-facts-free-speed-from-proper-shifting-44016/