Headset swap - a lot of work for about 2mm 
Since I decided I will run with Mafac center-pulls, I hit a snag that the 3mm Mafac front cable hanger could not safely be used with the original headset. From the Gitane doner bike, it turned out to have a great condition very low stack height headset. I could gain 2mm with a swap (and the vast majority of the 2mm pretty much saved from the lower race).
Removing the old headset went well. Since I'm not the kind of guy to own and mess around with a Park Tools crown remover, a very vintage high quality steel kitchen knife and hammer was used to gradually unseat the race from the fork crown with no damage. Loose ball bearings so all precautions were taken with some cardboard on the floor. Magnetic screw driver to pick anything up. The original headset came off in great condition
Things then started to get complicated. The Gitane 27mm crown-race was floppy on the fork
Then rummaged around and found another 27mm unknow crown-race which was a tighter fit but still not good. Then tried a Tange JIS 27mm just to understand better what was going. Took the decision to hand file the fork down to the "other nominal" French size of 26.5mm and use a crown race which would still do the job from a Peugeot (I think).
Did all of this filing then got in a panic when I was preparing to put the new cups in. The new cups measured up worryingly bigger than the old
. With some measurements of god knows how many headset parts, got the feeling that in the 50s the high end stuff was all made to fit together, but later 70s or 80s mid end stuff is all a bit nominal and not exactly the same across the big known bike manufacturers.
So yesterday afternoon I stopped and threw the headset cups in the freezer (in the baguette draw, but that's not important).
View attachment 733622 View attachment 733623
Just finished putting the new headset in. Went better than I expected but had to work quick (which isn't my strong point
) seating and pressing the cups. Kept it a bit of a mish-mash - old school way loose ball bearings at the bottom, caged at the top which I have seen done a few times. No photo's of putting the new headset in, I got in the zone and carried away
Dead lucky that only 1mm of steerer thread was still left to tighten it all snug. No tight spots and plenty smooth enough.
Wonder if the seller would like to do a swap with mine? Mine would be shipped in kit form with no assembly instructions. 
. You're probably aware that French threaded pedals are available with narrow and wide thread for skinny steel and fat alloy cranks 
1948?
