Peter Cole wrote:

I have never understood the desirability of folding, the trailer-bike
isn't very big.

Huh? My Halfwheeler is longer than any of my single bikes - way too
long to fit in my car, it would even be ungainly in the back of my
minivan, and there's no way to put it on my roof rack; but with the boom
folded it fits easily in the trunk/boot of my sedan.