算昏头了还是故意的？你好像忘了一个重要参数。给你机会重新算一下。

"if you shift at 7500 rpm, before the shift:

Engine torque = 140, wheel torque = 4*140 = 560, wheel force = 560 / R." Did you forget about the RPM? I will let you to redo the Math and figure out it yourself.

hint: 560*7500 / R vs. 700*5000 / R, not just 560/R vs 700/R. Maybe this will make you finally understand why your one-gear modeling is flawed as well. And you should also understant the importacne "gearing", which takes advantage of Power, which in turn is the combination of rpm and torque. Not the torque alone.

Actually, in ordr to maintain the maxium acceleration. The shift point should be passed the maximum HP rpm and right before reaching the redline.