Tandems

Do you have an independent pedaling system so that a child can ride a tandem and either contribute or coast independent of the adult?

We have a "Project Q" tandem and enjoy it very much. We have been partially disassembling the bike by separating the front and back halves by loosening the four joints and removing the top and bottom "boom" tubes. This means disassembling and reassembling the bike twice a week. It only takes about ten minutes to do so and isn't much of a problem at all.

My question is: is the frame designed for this type of use or are we causing any harm to the bike by doing this every week? Are we work-hardening the joints or somehow stressing the bike by continually assembling and disassembling it which is prematurely aging the bike?

What is crossover drive? It seems to be the differentiating factor between the first two models of Tandem Traveler Sport.