Re: Chain slack adjuster taking power?
Jim is correct. If the tensioner is installed right the difference in power drain would be negligible. In fact so small that I doubt seriously that you could tell. We're talking about micro differences in torque and we humans just don't have the ability to feel that small of a difference. My guess would be a difference in sound that your friend is hearing leading him to believe that the tensioner was draining power. The psychological aspect is probably responsible for the perceived difference, not the tensioner wheel.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"