Tandem Cycling - Shifting question.

Previously I raced ultra races on a Santana. We could never get that thing to shift properly with the front deraileur. Especially under load it either would not go on the big ring or it wouldn't drop down to the little ring. We bought all new chains/chainrings etc and we adjusted that thing so many times it isn't funny. The bike shop mechanic said it was because of the range between the big and little rings being too big. Fine, sounded logical to me. Fast forward to today and now I'm riding a custom Calfee and it shifts just like my single road bike and it has a bigger range than the old Santana. No issues at all, even under a load. The only thing I can think it could be is the spacing on the rear wheel. Could it be the wider rear spacing on the Santana hub makes the alignment just far enough off to create the difficulty in shifting the front deraileur on the Santana? I did one 200mile ride on a Cannondale 4-5 years ago and I don't remember it having shifting problems either but it was a fairly flat course. BTW, both bikes have Ultegra brifters and running gear with the exception of FSA carbon cranks on the Calfee.

My Santana shifts fine.

Previously I raced ultra races on a Santana. We could never get that thing to shift properly with the front deraileur. Especially under load it either would not go on the big ring or it wouldn't drop down to the little ring. We bought all new chains/chainrings etc and we adjusted that thing so many times it isn't funny. The bike shop mechanic said it was because of the range between the big and little rings being too big. Fine, sounded logical to me. Fast forward to today and now I'm riding a custom Calfee and it shifts just like my single road bike and it has a bigger range than the old Santana. No issues at all, even under a load. The only thing I can think it could be is the spacing on the rear wheel. Could it be the wider rear spacing on the Santana hub makes the alignment just far enough off to create the difficulty in shifting the front deraileur on the Santana? I did one 200mile ride on a Cannondale 4-5 years ago and I don't remember it having shifting problems either but it was a fairly flat course. BTW, both bikes have Ultegra brifters and running gear with the exception of FSA carbon cranks on the Calfee.I have no problems with the front shifting on ours. 2006 with Ultegra Triple 10sp.
Are you using the same exact group on the calfee or comparing and old group to a new one?

. The only thing I can think it could be is the spacing on the rear wheel. Could it be the wider rear spacing on the Santana hub makes the alignment just far enough off to create the difficulty in shifting the front deraileur on the Santana?

The Santana rear spacing does create a chain line issue, and the need for a longer bb spindle. If the chainline wasn't setup right on the Santana that could explain the shifting problem.

The Santana rear spacing does create a chain line issue, and the need for a longer bb spindle. If the chainline wasn't setup right on the Santana that could explain the shifting problem.

That's what I'm looking for! The Santana is still around and I've always thought that it should shift pretty much just like a single bike. That Calfee actually has older shifters on it. I'll see about checking the chainline on it. Is there a good way of going about that?? Should I just measure the BB spindle or should I be looking for a spacer of some kind?

Thanks!