The low gear got us up a pretty big hill. I'm actually surprised we managed because my wife isn't very muscular. The more urgent problem is the top end. I feel I need a 60T big ring. I counted all the teeth on all the gears but lost the numbers. I'll count them again.

The model is Zydeco. When we first got it, it seemed terribly whippy. Now we don't notice it. Either we had it set up wrong then or we have developed a pedaling style where frame stiffness isn't so important. I think the tires are a great size, and I'm quite happy about them. I don't like riding mtb tired on a single, as I find them too small in diameter, but I like them here.

Interesting update on the original post. I recently acquired a second tandem from my local nonprofit bike shop. It's a 1980s era fillet brazed Rodriguez, identical geometry to the Burley duet - - but finally got it rolling after a full overhaul and the difference is incredible! The Rodriguez just feels rock solid. Captain noticed the difference immediately too and felt much more relaxed. The only other difference between the two frames is that the Rodriguez has an oval profile top tube (and, of course, is nicer to look at). Could the method of joining tubes and one oval tube really make *that* big of a difference? Other strange thing, the Rodriguez feels much more squirrelly riding solo than the Burley does.

I don't fully understand what's going on here, but it's encouraging. Taking the rodriguez on a bike camping trip to the San Juans this weekend, so we can get in plenty of miles without too much traffic.

This forum has lots of engineering-types, so if I get this wrong I'm sure it will be corrected forthwith. My understanding of ovalizing the tubes is that it gives them a stiffness across the wide direction nearly comparable to a round tube of that diameter, so an oval top tube would stiffen the bike considerably side-to-side.

My guess is that a lot of this is a difference in trail between the two bikes.