The Kwiggle is folding bike that has been around for a while now (even though doesn't seem to be for sale yet): https://kwiggle.odoo.com/en_US/startseite
Apart from it's folding capabilities I was interested in the more upright riding positions which they seem to claim that "You ride faster and your quadriceps have to work less." (https://kwiggle.odoo.com/en_US/home-kwiggle-vorteile)
I find this a quite interesting claim in terms of efficiency. Is there more evidence of this, and if yes, why aren't more "city bikes" doing this?
Another interesting "city efficiency" aspect seems to be the movable seat which is highlighted more in this video and they claim "The movable saddle follows your natural hip movement.":
Personally I think the combination of the movable seat with a more upright riding style (which is what race riders do to increase speed) is a quite interesting combination!
So my question is about general efficiency of this approach. Is it an entire waste of energy compared to regular diamond shaped bikes or is there something to the combination of upright riding + movable saddle?
Personally I think most answers are addressed by non-european cyclist. In Europe (Netherlands and Denmark) an upright "dutch" bike is the norm for urban cycling and has showed several postural and efficiency advantages.
A dutch bike posture seems to be very similar to the one presented in this Kwiggle prototype:
With regards to the "swinging saddle" there's very little evidence showing how efficient this system can be. Personally it does sound interesting as the pedal stroke is leveraged by the hip moving towards the direction of the stroke.
Regarding the rest of the features of the bike, there's many things left to be desired, but the question is mainly about the "upright posture" (already established in Europe) and the "swinging saddle".
I'd be curious if there are any other "swinging saddle" prototypes out there since that seems to be the novelty of this approach.