Tobias Denkinger on Nostr: I am probably missing the point here, but you cannot really convert between mph and ...

I am probably missing the point here, but you cannot really convert between mph and min/mile. The first one is a unit of [speed] = [distance] / [time] and the second one is a unit of [time] / [distance]. (You swapped NGP and FTP in the last equation, so the end result is fine.)