revelo

That would be 15kg on rugged roads and even that is dubious. What is needed in a rack is stiffness, not static strength. A rack which flexes is much more likely to break than one which is stiff. Or the attachment bolts will break from all the flexing. A thin titanium tube can be half the weight but the same strength as a thicker steel tube, but the titanium tube will not have the same stiffness as the thicker steel tube. Also, titanium will lose much of its strength if impurities are introduced, either during smelting or welding. For aviation purposes, titanium is also accompanied by a bill of provenance, stating who the smelter was and then there are all sorts of quality control checks during welding. Doubtful whether this sort of quality-control is done with bicycle racks (or titanium bicycles, for that matter). Anything cheap made of titanium (Tubus racks are cheap by aviation standards) can be assumed to be made with titanium that was rejected by the aviation industry. Junk titanium, in other words. Fine for solid objects like tent stakes, sporks and whatnot and also for objects with non-critical welds, such as the spot weld for attaching a handle to a camping pot, but dubious for something like racks and bicycles.

The Tubus Airy is also too small to use Ortlieb back-roller plus pannier, and too small for my rack bag. Obviously, you can save weight by making something very small. All things being equal, a bike for a child is much lighter weight than a bike for an adult. And?

Finally, people worry to much about corrosion on bike racks and not enough about abrasion. Those Ortlieb panniers will eventually abrade the metal due to constant rubbing, whether the metal is steel, titanium or aluminum. In other words, I would expect to replace a rack every 50,000 miles or so of hard use (that would be 10 years at my rate of dirt road touring). The need to replace racks eventually due to abrasion is a very good reason NOT to get a Silk road bike, which has the rack as an integral part of the frame.