This is a good question... compatibility issues...
Seems Like the Dura Ace CN-7701 is narrow enough, I haven't tried it but Campy prices might convince me to experiment.
__________________
BMC Race Machine / BMC Team Machine / Rossin Record / 80's Pinarello Traviso / Merlin MTB / Raleigh "Folding 20" / Ti-Swift (!)
Erikson w/C&C couplers / Trek's: 2300, 1200, 990 / Jamis 'Sputnik'