You can get ~700% range with a Sturmey-Archer CS-RK3 with a 42 tooth chainring & an 11-42 tooth cassette. I have such a setup on a 700c gravel bike. Way more is possible so long as you mind the 1:1 low/low drive ratio.
A Haberstock Mobility Schlumpf drive is another option. I have the Speed-drive (1.65) mated to a Nexus 7. 400% range.
A (2.5) High-speed drive would yield 575% Even greater range could be realized if the HSD was mated to an Alfine 8...Around 720% Though, I don't know how often 90rpm at 35mph on a folder would be practical.
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I shouldn't have to "make myself more visible;" Drivers should just stop running people over.
Car dependency is a tax.