Thus, the design is constrained by the range of current production motorcycle, and will be compared using miles/kWh.
Convert the sentence from passive to active voice.
It's a bad sentence to begin with. You can't compare just one design, and it is difficult to imagine how a design might be expressed in mi/kWh.
So I'm going to assume that what is meant is that it is what is to be compared is the ranges of two motorcyles: a current production model and a new design. And to cast the whole in the active voice will require introducing an Agent who performs the comparison.
The range of the current production motorcycle constrains the design, and we will compare the ranges using miles/kWh.
But speaking of a range constraining a design is not very good either. What is probably meant is something like:
A constraint on the design is that its range should be at least equal to that of the current production model. We compare them in miles/kWh: &c