Wow!! Those rings look interesting. Surprised how oval the small one is.
I wonder how different their profiles might be if you lay those on top of Biopace rings of equivalent tooth count. It would be interesting if they might be close to Shimano's design. Then there will be the question whether Stronglight might have gotten in trouble for patent infringement with Shimano back then. Shimano was pushing the Biopace concept very hard into the market and would have protected their product very seriously. Interesting too that Stronglight used "Bio" in "Biostrong". Could Stronglight have made these under license from Shimano??

Chombi