@RichardCoffey: Thanks for ATS research and your friendly words.
On Spring 10 I asked Strida europe:
“The Taiwanese 2-speed gear of the Strida MAS is said to be very unreliable. Do you know more about that?”
Answer:
“The MAS Schlumpf cannot be ordered as a spare part.”
----- ? ------
@smitt53: Thank you very much for the pics, will there be more?
The Schwalbe Kojak tires of my 18" Strida, inflated at 8,0 bar, seem to lose air relatively fast (about 0,3 per day).
Did you make this experience as well?
@hydractiva: Fully agreeing to your verdict, I am sorry to say that I have trouble with your gearing description.
Please do not take this personally.
@All of you
My first impression after riding a few kilometers on the 16" Schlumpf Strida: at this moment I realized that I had not been biking for decades before I bought my Stridas in Spring 10:
The lower gear feels much too low for me and the higher one awfully high.
The smooth original 100:30 gear is suitable for a completely untrained stork leg but not the higher gear of the Schlumpf.
It’s true, with the higher Schlumpf gear you can go much faster … if you can.
But things are getting better every day…
There are no “hills” in the area I usually ride, but a few “drive-ups” or “raisings” hardly managable with the 16" original gear are nearly not to be managed with the 18" Strida. The lower Schlumpf gear lets me climb up these places without any problem, slowly of course. Acceleration in the lower gear is certainly much better than the original on flat road. After 2 or 3 rounds of the pedals it is advisable to switch to the higher gear, which brings me to shifting:
As smitt53 said, you will need practice first. But in my case shifting became automatic after 40 or 50 kilometers, meanwhile I shift almost intuitively and frequently. Always wearing high shoes, I kick the shifting button with the heel or ankle - the Strida aluminium pedals are a bit more slippery than the original black ones and support the little sideways movement of the shoes better.
Also shifting without interrupting the movement of the cranks is possible, it is just a question of the right moment (and really cool!).
With increasing practice I am on the way to handle the higher gear, my top speed on Schlumpf 16" might be around 22 km/h at the moment, and it feels the same as top speed on 18" with original gear, but at lower cadence.
By now I have ridden about 80 km with the Schlumpf 16" and about half this distance on the 18" Strida for comparison.
For better understanding of the gear mystery I did some research on the web, then I took a ruler and used these online gear calculators:
wisil.recumbents.com/wisil/gearinches.asp
The tires:
size; name; description; diameter (measured), circumference (arithmetical); circumference (measured)
16"; Kenda Kwest; 16 x 1,50 (40-305); 38,5 cm; 120,95 cm; 121,2 cm
18"; Schwalbe Kojak; 18 x 1,25 (32-355); 42,1 cm; 132,26 cm; 132,6 cm
Based on the two measured diameters of the wheels, the gear inches were calculated, and here are the results:
the first values are calculated with wisil, the values in brackets are from the soulbike calculator.
16" with original gear: 50 (50,4) Schlumpf low: 40 (40,4) Schlumpf high: 66 (66,7)
18" with original gear: 55 (55,3) Schlumpf low: 44 (44,2) Schlumpf high: 72 (72,9)
From my subjective feeling and corresponding to the results I have to say that the higher Schlumpf gear with Kenda 16" tires is certainly not the same as the original, as hydractiva mentioned, maybe her/his gear calculations are based on different tire sizes?
Anyway, I’ll have to train a huge load before changing the wheels of my Stridas against each other 
Here is another interesting thread about sport duos:
savedbybikes.com/blog/blog/sport … mpression/
Did you know that Strida Europe offers the MAS again, “available third week of June”?
Update 06.07.10: “available last week of july”
Update 06.08.10: “available last week of august”
Warmest regards