A quick measurement of the distance between the look nut and the spokes of the rear drive side revealed that Campagnolo rear wheels have the clearance needed to add another sprocket.
Before I started the lath I decided to use the same center-2-center dimension as the shimaNo 10-speed, 0.5*1.60mm +2.35mm+0.5*1.60mm =3.95mm in order to be somehow compatible at least as the shifter increment from sprocket to sprocket is concerned. In practice it's after the Campy 11 speed rear wheel is replaced after an defect by an generic shimaNo 10-speed no problem to remember that there is the possibility to through the chain between the last sprocket and the spokes.
The small campy sprockets with the integrated spacer as well the spacer were machined to my new 11-speed spec 0.5*1.75mm+2.20mm.0.5*1.75mm=3.95mm and the entire cluster moved 0.90mm+0.10mm closer to the spokes. This is done by machining the Aluminum carrier on the internal side. The only bit of difficulty is to disassemble the riveted sprockets on the carrier, machine it to reduce the clearance to the spokes, to obtain the 2.20mm spacer and to assemble it afterwards.
Now after the sprocket turned out to be functional I started to focus myself on the Ergopower shifter. Space for the 11th groove for indexing was found quickly and the transmission ratio has been reduced by adjusting the radius of the drum which winds up the cable proportionally.
After the Ergopower has been assembled I mark the housing and the job is done.
