Originally Posted by Earthloop

Yes. Unfortunately it's still wrong. Ambidextrous skidders should double the number of skid patches if and only if the numerator is odd, or (equivalently) they should double the number of cog teeth before simplifying the ratio.

Consider a 50/20 ratio for example. This is 4 skid patches (each half-turn of the crank advances 25 chainlinks, so one and one quarter turns of the back wheel between skid patches) but since 5 and 2 are not both odd the formula above gives 2 skid patches.