I recently acquired this Gazelle Champion Mondial in 531 Speedstream tubing . It is from 1986 (probably) but still of interest to the list IMO. Gazelle's special product manager informs me that Gazelle has built 25 of those frames at the most. I'd appreciate it if anyone can shed more light on the use of Speedstream tubing.
http://www.wooljersey.com/
Freek Faro
Rotterdan Netherlands