I was about to post this also. They even mention that the Specialized CG-R (formerly Cobble Gobbler) might be ideal for tandem stokers! It's rare that this usage is mentioned in the mainstream cycling press. My wife is certainly happy with it on our tandem.

I've used the Ritchey, Specialized, and Thomson models mentioned in the article on a single bike, and my subjective favorite is certainly the Ritchey.