Titanium will match steel in every way, at a lower weight and higher price. A good steel hardtail is simply an inexpensive way to get into XC riding. Aluminum lacks the stregth of the other two, so they draw the tubing walls out thinner and make the diameter larger. This makes a strong and light bike, but uncomfortably stiff. Steel and Ti are known for their "Compliant" rides. They could be made as stiff as aluminum, but the selling point is comfort. Our tandem is made out of titanium, as it offers a much more comfortable ride than a comparable aluminum one would, but it also cost twice as much.