CroMoly, the typical steel alloy that's been used for decades, is commonly drawn to 9/6/9 gauges. The seamless CroMoly used by Santana can be drawn to a higher-performance 8/5/8. Some tubing manufacturers harden their tubes in order to achieve 7/4/7. Problem is, because hardened tubes are brittle, a frame built from these tubes is more easily damaged and has a shortened fatigue life. While hardened tubes aren't a bad choice for a (more disposable) single bike, a good tandem should endure for decades.
In concert with Europe's leading car manufacturers, Columbus has developed a lightweight alloy tube to protect passengers against side impact intrusion. Columbus' amazing Niobium is not only an achievement in automotive safety, a double-butted version of this tube heralds a new era of bicycle design. Because this new steel alloy gets its strength from rare elements instead of risky heat treatment, dependable impact-resistant tubes can be butted to 6/3/6 gauges. If you want the planet's lightest, strongest and fastest steel tandem, insist on a Team Niobium from Santana.
The Team Niobium tandem is available at our North Shore store in Fox Point.