Here is an interesting article in A to B magazine, December edition, describing the prototype 2 and 3 speed plastic epicyclic gears developed by Mark Sanders for the Strida 3.
Hi Minkair,
As most of us are not subscribers of A to B magazine online, we cannot read the page in full size. Could you tell us briefly what the article is talking about?
I can only find some pictures of the prototype plastic epicyclic geared front pulley developed by Mark for the Strida 2 on his web albums. However, I know noting about it. 
Regards,
Amuro
Certainly, Amuro.
A reader wrote in to ask A to B magazine about a 5/7 speed Strida, gears in bottom bracket pulley. Editor (David Henshaw) replied those were Miyata/Shimano crankwheel epicyclic gears from the 80’s adapted by Strida owners. He then went on to describe other Strida multi-gears (MBi from Korea, Sturmey bottom bracket gearbox, Ming rear pulley multispeed) and his own favorite - Mark’s plastic 2 or 3 speed crank pulleys with the freewheel built-in (ie Strida 3). He said the idea was well-developed by Mark with working prototypes, but never proceeded to production 
The pictures are the same as yours, except no exploded view.
regards,
Minkair.
Great! I need a cheap gear for my Strida.
Here is a good video to understand how Epicyclic Gear works 
Video : http://youtu.be/ECljAo1q1RQ
Description : Planetary gear set in motion. First the planet carrier is held stationnary, then the sun is held stationnary, finally the ring gear is held stationnary.
Thank you very much Minkair! 
By the way, what are they actually?
There is a rumour saying that there will be a 3-speed Strida next year.
[url]Very frustrated at lack of Strida Sport Duo - #13 by madfolder]
Does it mean that the “Ming rear pulley multispeed” will be used on the 3-speed model next year?