Single bikes outnumber tandems by more than 1,000:1. As a result, it is not economical for bicycle tubing manufacturers to develop superior-quality tandem tubesets. Unless tandem builders pay the development costs for a custom-drawn tubeset (or buy their tubing from us), they instead use generic tubing with a lesser degree of performance.
Some builders simply use the smaller-diameter tubes designed for single bikes. Because tandems produced from single bike tubing are not stiff enough to be stable, conscientious builders realize they must provide stiffer tubing. There are but two ways to make a tube stiffer—increase its wall thickness or diameter.
While thicker tubes are propor-tionally stiffer (20% thicker equals 20% stiffer), a larger tube yields a cubed increase in stiffness (a tube that’s 20% larger is 73% stiffer). Problem is, unless a tubing mill simultaneously increases thickness, larger tubes are harder to draw. The most expensive tube to produce is one that is both larger and thinner. Because this combination can produce the highest stiffness-to-weight ratio, it is found on every model of Santana.