M3L here..

the 2 speed uses the same hub as the 1 speed .. 2 cogs ,+ the shifter, & lever (& bell?) its on the left grip side.

Its pushing the seat on the seat post all the way down that keeps the rear end from unfolding
(you do that Last)

the hook on the left side of the front fork , hooks over the right chainstay . 1
and the steering mast catch on the right fork crown keeps that closed in the folded position. 2

You have an Idea what size you want that 1 gear to Be?

high would be the 12:54. low would be the 16:44