14 gauge spokes are not overkill- they will give you extra lateral stiffness in your wheels that you will appreciate, especially when doing out of the saddle work such as climbing or sprinting. It makes a difference, more so on tandems than on singles. People that build wheels will tell you that you can build a better wheel with double butted spokes, but the truth is that it's easier to build a wheel with double butted than with heavier straight gauge- it's easier to tension and true a wheel done with DB spokes because they stretch more easily than SG spokes, which is exactly the reason that a wheel done with SG spokes is more laterally stiff.

Hah- I'm ranting already and no one has even had the opportunity to refute me yet I'll save the rest of this argument for when someone jumps in to tell me I'm wrong.

One other thing- the weight savings of DB over SG is negligible, especially on a tandem. Far and away the most practical way to reduce the weight of the system is to lose weight from your body if possible. My wife and I have lost 30lbs between the two of us in the last six months (we're a 280lb team now) and the difference is stunning both when accelerating and when climbing.

Rick the Curmudgeon