Dreamslide Global

dreamslide vs the various elliptical scooters

I read through the BiomechanicalStudy.pdf paper on your site and thought your comments about elliptical pedalling motion matched the conclusion I had come to when I was trying to figure out why that motion works.  Basically they ellongate the ellipse so most of the leg movement is horizontal with relatively little vertical.

 

But now that several companies are making elliptical pedal scooters some of them seem to perform pretty well.  In particular the elliptigo has very credible claims regarding its speed, distance, and hill climbing ability.  So that's making me re-think the merits of that design.

 

The elliptigo also has an internal hub with 8 gears so that may be a big part of its performance.  In the videos I've seen of the dreamslide it seems to have quite respectable looking quickness too, but have you had a chance to directly compare elliptical pedaling vs the APS?

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Hello Declan, I am Jean-Marc, the inventor of the dreamslide.
The first important thing to understand is that there are many types of elliptical machines with very different kinematics. On most of the elliptical trainers, the ellipse is quite flat and the major axis is horizontal. Thus, the most powerful muscles of the body, the gluteus maximus and the quadriceps, work just a little. So one cannot produce much power with these machines which have been designed for exercising but not for propelling a vehicle.
The Elliptigo is quite different because the major axis of the ellipse makes an angle of 20° with the horizontal. Thus, pedalling on the elliptigo is like walking on a steep uphill road and one can produce a mechanical power close to regular pedalling power. However, the height extension of the movement is not as large on the Elliptigo as on the Dreamslide (24 cm versus 34 cm).
Other elliptical bikes, like the StreetStrider for example, have a kinematic which is very "horizontal" and therefore which is not very efficient to propel a vehicle (but however is interesting for exercising).
The Dreamslide is not at all an elliptical machine because the movement is circular like on a regular bike, but the pedal is much faster in the upper part of the circle than on the lower part. So the motion is close to running with small steps but raising high the knees.
The first advantage of the circle upon the ellipse is that the pedalling movement takes far less space (34 cm for the Dreamslide versus 60 cm for the Elliptigo). It is the reason why the Dreamslide can be much shorter than the Elliptigo (total length of 120 cm versus 190 cm) and much lighter (11 kg versus 18 kg).
The second advantage is that, the perimeter of a circle is smaller than those of an ellipse of the same height (the pedalling perimeter is of 107 cm for the Dreamslide versus 136 cm for the Elliptigo). Therefore, the pedalling pace can be faster with a circular trajectory than with an elliptical one for the same average speed of the feet. And a high pace of pedalling is necessary to maintain a large mechanical power (beyond 200 Watt). So, There are good reasons to think than the horizontal ellipse (or even an ellipse with some incline) is not very efficient for high power output (but it lacks some experiments to prove this reasonable hypothesis).
The third advantage of the Dreamslide's kinematic is that there is no upper dead spot because the perceived leverage is very long in the upper part of the circle. With a dreamslide, one can be very strong on the complete trajectory of the pedals. Thus, the gears are less essential than with a regular bike.
As a conclusion, I would say that the Elliptigo is a well designed product for people who like the elliptical trainers and want to train outdoor. The Elliptigo offers a good elliptical kinematic with a large horizontal stretching of the legs and sufficient vertical movement to make work the quadriceps muscle. It is also a very stable machine because the wheelbase is very long (137 cm), much longer than those of a regular bike (around 105 cm).
But the Dreamslide is better for people who prefer a very handy (because of the 82 cm wheelbase), light and responsive machine. Because of the APS,  the Dreamslide gives great accelerations and allows a very high power output with sufficient training.

Wow, that is an amazingly detailed and thoughtful response!  It's so nice to get feedback like that straight from the developers.

 

I had no idea what the dimensions of the movements on the two vehicles (dreamslide and elliptigo) were, and the greater vertical movement while the feet trace a shorter total path length sounds like a real win for the dreamslide.  I guess time will tell whether you guys get the award for most efficient drivetrain for a scooter, but you're certainly a contender.

 

And I do especially like how small and portable the dreamslide is.  As an urban utility vehicle or "last few miles" range-extender for use with public transportation size matters and the dreamslide is more conveniently sized than just about any other scooter out there (don't let that stop you from making the microslide though, that would be pretty awesome too).

 

 

Back to the drivetrain conversation, the angle of the ellipse makes me think that one of the reasons people talk about the elliptigo climbing well is that the ellipse gets rotated to have higher and higher vertical travel as you angle the elliptigo up a hill.  I think ergonomically there's going to be some limit where their bike gets very uncomfortable doing that, but at least they would get to generate some extra power on the hills as long as the rider can deal with the ergonomics.

 

I know I've seen a video of someone riding up Fargo street in LA (32% grade, or 17.7 degrees) on an elliptigo.  I think that angle would increase the vertical travel on their ellipse all the way to 43 cm at that grade (although they still have a longer total foot movement to contend with).

 

So what happens to the APS when it's rotated?  Clearly the path is still circular, but it seems the gear ratios around the pedal stroke could get skewed off their optimal values.

Not that extreme hill climbing is the most important measure of a scooter of course.  Sometimes it's easy to hyper-focus on things that don't really matter that much, but I'm still curious how well the APS handles moderate rotation.  Maybe this could be tested on one of those static machines you made?  I don't really know to what extent scooter riders keep their bodies exactly vertical with the world while riding up steep hills vs leaning back so their bodies maintain the same relative-alignment with their scooter though.  Any thoughts?

 

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