On 2017-12-01, Tanguy Ortolo wrote:
Gregory Sutter, 2017-12-01 09:16+0100:
This commercial mudflap is retroreflective, has just the right
amount of flex and generally works really well:

http://www.rainydaybiking.com/Standa...Flap-p/100.htm

This may be a bit expensive to ship to France, but I will try to find
something similar here. Thank you!

You might try these or similar, which will be more readily available.

https://www.bikester.fr/accessoires-...boue/8517.html
https://www.bikester.fr/sks-accessoi...ir-361025.html

Additionally, your local randonneuring club will likely have some
lively opinions on the best products for the purpose!

--
Gregory S. Sutter Mostly Harmless

http://zer0.org/~gsutter/