Upright bicycle efficiency & seat movement 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 &quot;You ride faster and your quadriceps have to work less.&quot; (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 &quot;city bikes&quot; doing this?
Another interesting &quot;city efficiency&quot; aspect seems to be the movable seat which is highlighted more in this video and they claim &quot;The movable saddle follows your natural hip movement.&quot;:

                
            
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?
EDIT
Personally I think most answers are addressed by non-european cyclist. In Europe (Netherlands and Denmark) an upright &quot;dutch&quot; 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 &quot;swinging saddle&quot; 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 &quot;upright posture&quot; (already established in Europe) and the &quot;swinging saddle&quot;.
I'd be curious if there are any other &quot;swinging saddle&quot; prototypes out there since that seems to be the novelty of this approach.
When I consider all the claims made, I believe they are probably true and verifiable... Not once do they tell you what they are comparing their product to, they lead the reader to presume...
&quot;You ride faster and your quadriceps have to work less.&quot; - compared to what?  Walking
&quot;- If you have a Kwiggle with you, you will explore cities and landscapes faster, further, more independent and more flexible.&quot;  - Key is is the first word - &quot;If&quot; followed by faster/further/more independent than what? Obviously, if you have their product with you, you almost certainly won't have a competitors product with you.
&quot;The standing position is also unique in the world. You get more force onto the pedal.&quot; - More force than doing what on what? If you stand on a regular bike, you have the same position and same advantages, but you set the saddle up for more efficiency - by pedaling faster with less force (i.e. spinning - which is more efficient when trained)
Every one of the claims falls into the same kind of questionable claim. Probably spend a fortune on legal fees ensuring they don't breach various consumer protections laws around the world.
Note - this is a essay on the sales claims of the product and makes no assessment of the product itself.