Thanks for playing! The RPM system has a lot of factors. The main thing that determines damage on each collision is the speed you are moving at and the weight difference between you and your opponent. If you get hit while sitting still, you will take a much larger portion of damage than if you were dashing at them. Likewise, having higher weight lowers damage taken in each exchange. In terms of strategy there's many ways to go about it, but your method is the most reliable :)