Doland,
As others have pointed out, the Medaille d'Or rims do weigh in at 260gms!! I have built two sets of wheels using these rims and can say they do not "like" high spoke tension. I have not ridden on them, as I sold the first set, and the other set is currently on the PX-10 I am selling (eBay). They do seem very fragile and would not like potholes, but they make contemporary Mavic Heliums feel heavy!! My "guesstimate" would be if you are over 160lbs be careful (but then riding style is so important....)! If I ever do a "field test" I'll report to the group, but then again the roads in this part of the country can be devastating to light rims (GP-4's work very well for all around purposes).
Take care,
Chuck Brooks
Malta (upstate)NY