Originally Posted by Carbonfiberboy

Oh, the OP is absolutely correct. However . . . the real reason that tandems have a rep for being slow climbers is that the vast majority of tandem teams are the result of the stoker being a much slower rider than the captain. The couple got sick of not being able to have fun riding together and bought a tandem resulting in an improved relationship. That's all there is to it, and good on us and all those who've done the same. We rode RAMROD on ours when we were 135. Yeah, we were slow, but we made in under the time limit and got our matching jerseys. Yeah! As the OP says, on the flat we keep up with the singles or even pull, but on the climbs we're off the back, though we often get them back.

I have data from a tandem team, friends of ours. They used to ride singles together. She's a very good rider, but he is really strong, so on a pass climb his HR would be 110 and hers 145. So they bought a tandem. On the tandem, their HRs are about the same and they both get a good workout. She's actually the more aggressive rider.