Oh well…I’ve totally overlooked that the cranks of the Strida C1 are made of Carbon, too!
So, there ARE lightweight Strida cranks existent and they are available as a spare part.
Just amazing their price - expect about 450 € for a pair of these cranks 
(Price from German distributor.)
Here’s a nice parts oversight:
http://www.gsglobal.co.jp/bike/STRIDA/Option/index.html
…maybe Magnesium pedals?
