@Karstan@driusan whatpressureyourunning, rolling resistance etc? You could dial all of those parameters into the motor simulator to match, but I would expect wind resistance between 20-28mph to be significant vs at 18-20mph, tuck and lycra or not. All other things being unchanged (hard to match the tire performance when the rim size is different though), you should get 20/28ths of the prior speed. Sounds like 10% higher losses though?