Caliper

I'm playing around with retro-modernizing an old Schwinn Passage that I've been enjoying riding. It's currently got a 7sp cassette riding on a modern freehub (ie: 10sp compatible) with 7sp downtube shifters. I am finding that I've grown just too accustomed to shift levers on the bars so have a set of 8sp Campy Ergopower that I'm intending to put on there, since Campy 8sp spacing is the same 5mm per gear as 7sp... But, that big spacer for the 7sp cassette got me thinking, has anyone gone and just slipped an extra 7sp cog and spacer onto the freehub and made an imitation 8sp Campy cassette? Width-wise the math says it should work, right? Is there anything I'm overlooking that would prevent this from happening? Yes, I've got the appropriate Campy rear derailleur.

styggno1

Do you want to avoid the spacer aestethically or are you worried about getting the chain on the spacer on the 8th click? If the latter - no need for the 8th cog. Just set the outer and inner limits for the derailleur in normal manner and the derailleur stops there. You will have one "click" too many at the ergopower and I would set it up starting on the second gear-click - avoiding excess cable slack if you happen to use a click too much.

Grand Bois

There will be no extra click if you set it up correctly. Cable tension won't allow it. Do not start at the second gear click.

Caliper

Not worried about dropping the chain, I do trust my limit screws! The spacer does put the cassette far out and results in the chainline being biased toward the larger cogs. Adding another cog (which would be an in-between on the outboard end) would move the chainline more where it should be while also using all the clicks on these Ergopower levers. Yeah, I know I could also get a longer spindle on the crank, but this way just seems cooler.

Caliper

Well, I went ahead and ordered a second cassette off eBay to give it a shot. 7sp parts are affordable enough, especially when 8sp Campy freewheels aren't.

Guess I'd better get those ergo levers assembled...