It wasn't the Crankarm - it was the titanium BB axle !
The race was @83-84 and I believe it was Paris-Tours, but I might be mistaken.
The failure of this axle was reportedly one of the reasons why Gitane switched to the Spidel parts group for the next one or two seasons.
I say one of the reasons, because usually these decisions were often based more on which companies discretely paid off the respective Directeur Sportifs, than anything else. Especially, but not limited to, the old days . . .
Just Ask Cyrille,
Mike Fabian
San Francisco, CA