Honestly, you'd go flying over the handle bars upon hitting the tiniest twig.
I've been riding Montague Bikes for years -- on the other end of the folding bike spectrum. Full-size wheels, rides so much smoother. Doesn't fold down as small but it goes in the trunk of a car or can be carried on the train and that's all I really need.
I also ride Montague Bikes. I'll give my use case. I need a normal, full size bike for most of my riding. However, sometimes I need to put my bike and a few others into the trunk of a car - the Montague folds small enough to make this happen. To have the ability to fold it into vehicles I think there is some added weight compared to other bikes in the frame thickness as it does not have the durable standard diamond frame shape. Also, their flip down bike rack to kick stand is a really cool design.
I've been riding Montague Bikes for years -- on the other end of the folding bike spectrum. Full-size wheels, rides so much smoother. Doesn't fold down as small but it goes in the trunk of a car or can be carried on the train and that's all I really need.