I'm swapping out the bottom bracket on my Bertin C37 and was planning on using the IRD French cups with either a Tange or IRD BB, but I just measured the shell width with my digital caliper and its right around 70.80mm?! I was under the assumption that French bottom brackets were 68mm. The thread on the cup I've removed measures 34.75mm... I haven't attempted to take out the fixed cup yet but am now unsure of what I'm dealing with. The BB that was in there originally is a TA but the spindle is pretty beat up, cups look okay. I ride in the rain a lot and wanted to try a sealed cartridge. I think the bike is maybe late 60's or early 70's? Any insight would be greatly appreciated!