Originally Posted by 2gether84

This board has been really helpful and I appreciate everyone's willingness to help and share your years of tandem expertise. While digging through the archives I found this link from TandemGeek.
https://www.precisiontandems.com/artdwanwheelsize.htm

Originally Posted by B. Carfree

The work by the Bicycling Quarterly crew, which is affiliated with Compass Bicycles, shows that for a given tire wider is indeed faster. My experience is that the Compass 26 X 1.5" tires had MUCH less rolling resistance than the Fat Boys. We have a few places on our regular routes where after cresting a hill we roll without pedalling downhill into a flat spot before either approaching an intersection or another descent and the difference is quite noticeable. With the Compass tires, we don't pedal on those stretches and maintain our desired speed. With the Fat Boys we have to pedal to maintain that speed. The 26 X 1.75" had even less rolling resistance.

More comfort, better handling, lower rolling resistance: what's not to like about fatter? Okay, they are a bit heavier, so you may notice that. The market for truly lightweight 26" tires just isn't big enough for the Compass folks to pay for the molds to make them (yet). But there wasn't much of a market for 650B when they started pushing them either, so I have hope.

Originally Posted by Mocharider

Our results are similar. I can't quantify it with a direct test because after the 1st ride on the Compass tires I threw the fatboys in the recycling bin. Yes they are made in a pacela mold and in your hands they look identical

Originally Posted by B. Carfree

Junk like what Dwan wrote in that link are part of why I didn't purchase a Co-Mo when I bought my last tandem, even though I live in the same town where they are made. He more than doubled the actual diameter difference between quality 26" tires and what most people ride for 700C. Also, I guess he's never ridden with people who have custom tandems built with 26" tires to accommodate short-torso captains (less toe overlap) if he thinks they are somehow inherently slower than 700C. My wife and I have completed double centuries in 9 hours on 26" tires and have known others who were an hour ahead of us, also on 26".

Originally Posted by dave42

Another thing. You'll spend more actual time climbing than descending if you have hills, so then that one higher gear is surely irrelevant.

Originally Posted by B. Carfree

The work by the Bicycling Quarterly crew, which is affiliated with Compass Bicycles, shows that for a given tire wider is indeed faster. My experience is that the Compass 26 X 1.5" tires had MUCH less rolling resistance than the Fat Boys. We have a few places on our regular routes where after cresting a hill we roll without pedalling downhill into a flat spot before either approaching an intersection or another descent and the difference is quite noticeable. With the Compass tires, we don't pedal on those stretches and maintain our desired speed. With the Fat Boys we have to pedal to maintain that speed. The 26 X 1.75" had even less rolling resistance.

More comfort, better handling, lower rolling resistance: what's not to like about fatter? Okay, they are a bit heavier, so you may notice that. The market for truly lightweight 26" tires just isn't big enough for the Compass folks to pay for the molds to make them (yet). But there wasn't much of a market for 650B when they started pushing them either, so I have hope.

Originally Posted by gracehowler

Plus one on that, we purposely chose a davinci because of the extra gears, but also chose 26" wheels because of our size. And we will say that living in Colorado, lower gears are a must and used a lot, especially loaded.
R&J