Originally Posted by
Jipe
What I can say based on my personal experience is that its not true for at least one of those short bi-fold, the Btwin Fold Light, on which the position is too upright due to the frame shortness.
The picture below is an official picture of Btwin/Decathlon published by Btwin to promote this bike.
Well that seems to confirm my suspicion that the issue for tall is not height, but reach. This reminds me of my first-gen Dahon, my knees would sometimes hit the handlebars when standing climbing. But notice in the above bike, how close in angle the handlepost is to the steering axis; I think that has room for at least a vertical post, possibly forward-canting. The head tube may be a bit laid back in angle, hard to tell because the frame monotube intersects at a much different angle than my bike, but Bromptons also have a similar head tube angle I think, and they steer fine with more forward handleposts.
Is it me, or does that bike have a double-folding handlepost with two hinges?