The fourth most abundant metal and ninth of the nine elements that account for over 99 % of the mass of the earths crust, titanium is not really unobtanium, notwithstanding its reputation. However , getting titanium out of the earth and turning it into bicycle parts takes an enormous amount of energy. Part of titaniums legendary appeal resides in the proven fact that its strength-to-weight ratio surpasses any other metal, and that it is highly resistant to corrosion.
Named for the Titans of Greek mythology, the tensile strength of some common titanium alloys approaches that of high-strength steels and far surpasses that of aluminum, without being brittle. Maybe more importantly, titanium, like steel and unlike aluminium and magnesium, has a fatigue limit, implying that if the tensions are kept below that amount, it’ll never fail from fatigue. Its a high fatigue limit at that, thanks to its high tensile strength. The Youngs modulus ( rigidity index ) of titanium is around half that of steel, but so is its density. Titaniums density is high enough that tubes can’t be made as stiff for a similar weight as aluminum or magnesium ones, because heavier walls are required to forestall buckling with huge diameter.
The anti corrosive properties of titanium are striking. Nuclear submarines are made from it so they will not corrode in caustic marine environments, and unpainted titanium bicycles and parts simply dont rust. Titanium isn’t brittle either ; it can be stretched around twice so far as steel and 4 times as far as aluminium before being permanently deformed. This gives titanium frames survivability in crashes, since they are going to be far more likely than others to spring back after impact. Eventually, the ride of a titanium bike is often smooth, because a frame designer can select thin tube diameters and wall thicknesses to provide a supple ride without sacrificing longevity.
Due to titaniums capability to stretch and return to its original shape, drawing it into tubes demands bigger and more powerful machines than those needed to draw steel tubing. Welding requires enclosure in an inert-gas atmosphere, and weld contamination must further be stopped thru careful cleaning. Machining titanium requires very pointed tools and specific speeds and lubricants ; copper-laden lubricants are used on titanium threads, and it is not endorsed to thread titanium parts into each other.
Titanium excels for bicycle frame tubing and dropouts as well as for lightweight bolts, axles and saddle rails.
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