What You Need to Know About Bicycle Frames Part 3


Once you begin considering titanium as a material for a bike frame – you’ve probably decided to invest a considerable sum into your bicycle. Titanium is one of the most expensive bike frame materials. While it is among the most abundant elements on the planet, it is notoriously difficult, and therefore expensive, to refine and work with. But some would argue that it is worth the expense because it takes the best characteristics of steel and aluminium and combines them in a near-perfect package.

It has a high resistance to rust and is much more lightweight than steel, while also being much more yielding than an aluminium frame, making titanium more comfortable. It also has a higher resistance to fatigue than both aluminium and steel. That’s why riders who are looking for high durability with outstanding performance and are not afraid of spending a large amount of money, have titanium frames on their shortlists.

Initially titanium bicycles were made out of pure titanium, but those frames lacked stiffness to get both the durability and performance that would justify the price. It quickly became evident that an alloy needed to be used in order to realise titaniums full potential. Today, there are two main alloys used in the bicycle frame construction. There is the 3AL/2.5V, which means that the frame has 3% aluminium and 2.5% vanadium mixed in with the titanium. Not a terribly creative way of naming an alloy, but it makes perfect sense to the initiated. Which is why the second alloy follows the same naming logic. The second alloy which came to bike frames a little later was the 6AL/4V, which of course meant it was 6% aluminium and 4% vanadium. What both alloys have going for them are the stiffness and yield. Meaning that they will have a degree of flexibility that if offered by aluminium for example, but in the event of high-speed impact, the titanium frame is much less likely to deform than an aluminum frame. It was the desire to get a frame as stiff and light as possible that drove the development of the 6AL/4V alloy. However, as titanium bicycle frames go, the 6AL/4V is significantly less common than the 3AL/2.5V.

The differences in percentage of added materials to make the alloy might not seem that big, but they are highly consequential. In fact, the difference in material properties are such that they require different methods of manufacture when it comes to bike frames. The 6AL/4V is notoriously difficult to shape, even into something as simple as a tube. This alloy’s bike frames are made of tubes that are rolled from sheets of titanium alloy into tubes, with the side then welded. As always, the more complex the manufacture, the more room there is for error. So most fans of titanium frames stick with the 3AL/2.5V frames most of the time. But even then titanium represents a challenge, which limits the variety of geometry a titanium frame can offer.

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