My biggest question is the combination of an extremely short wheelbase, small wheel diameter and, perhaps more importantly, the negative fork offset and the steep head tube angle. It seems it would be extremely easy to get thrown over the handlebars when hitting an obstacle... What's your reasoning behind this geo? Is it only space saving?
First of all: The fork offset is needed to obtain the same trail as with a normal bike. Large wheels need to bend the fork forward in order to reduce the natural trail for easier steering. Small wheels need to bend the fork backwards in order to get the same effect, because the natural trail of small wheels is to small. Just look on a shopping cart. The fork of the steering wheels is bent backwards too.
On Kwiggle you ride upright with a small wheelbase. So you have to adjust a little bit and you should pay a little bit more attention to the road. We have so many customers who have mastered that with bravour, so we stopped worrying about it.
Only with this small wheelbase it is possible to get a bicycle folded to handluggage size.