Unfortunately there is nothing mentioned on the efficiency of a fixed gear drivetrain. Most of the drivetrains measured an efficiency of around 92 to 94 on average in the article, which is lower than I expected. I had the assumption that all drivetrains were nearly 100 percent transfer of energy, and that all the differences were miniscule. Plus when you add in dirt and old chain and everything else that modern bikes develop, I'm guessing these numbers would be even lower.