Originally Posted by
repechage
Prestige and the Volumetrica both have M cut out bottom bracket shells.
The Volumetrica will have some form of rear brake cable housing control brazed on or in.
Sure, the "M" cutout wasn't limited to the GC. But the other possibilties would have braze-on TT cable guides. "M" cutout and clips instead of braze-on cable guides = GC.