The kinetic energy at 100 km/hr is 0.5*m*v*v and that is with a bike+rider of for instance 250 kg 0.5*250*27.77*27.77=96450 in both tests
This kinetic energy at 60 km/hr is 0.5*250*16.66*16.66=34722
So without the tail enengy consummed by air and roll resistance is 96450-34722=61728
Now with the tail. Energy left at 62 is 0.5-250*17.22*17.22=37076
So energy consummed in this case is 59374. (so approx. 4% less)
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