So you essentially have to calculate and execute that all in a single moment? I suppose it becomes a second nature after much practice.Let say you are in 4th, going at 100km/h and thinking.. hmm i need more speed. since you are in 4th. you are probably going at around 3500 rpm. To travel at the same speed in 3rd, you have to achieve an rpm of 4500. So you push in the clutch, shift into netural, then let of the clutch, rev up to 4500, then shift into 3rd and gun it.