There’s two issues here – how strong titanium is and how difficult it is to weld.
Weight for weight, titanium is stronger than steel, but volume for volume, steel is stronger (steel is 70% more dense than ti). So a ti frame can be just as strong/tough as a steel frame, even though it’s lighter. But on the other hand if you fit a ti bolt into a hole designed for a steel bolt, the two bolts are the same size/volume so the ti one is likely to be weaker. That’s not to say that a stem designed for ti bolts isn’t perfectly viable, but the designer may well specify bigger (but still lighter) bolts than he would have done if he was designing for steel bolts.
Titanium is difficult to weld. Only a few repairers in the UK work with ti. If it wasn’t difficult, Argos and the others would repair ti as well, but I believe you need special facilities. What Wikipedia says (anyone know if it’s right/wrong?) seems to reflect some people’s experience of cheap ti frames - “All welding of titanium must be done in an inert atmosphere of argon or helium in order to shield it from contamination with atmospheric gases such as oxygen, nitrogen or hydrogen. Contamination will cause a variety of conditions, such as embrittlement, which will reduce the integrity of the assembly welds and lead to joint failure.”
But I can’t see why anybody would use anything but aircraft grade ti on a bike frame - not to use it is bordering on fraud. And anyway aircraft grade ti tubes aren’t exactly in short supply or exotic or anything. My favourite stat (again from Wikipedia) is that there is 145 tons of titanium in an Airbus A380. That’s just one plane, and that’s quite a lot of ti - it’s the weight of 90,000 bike frames. I’d be surprised if the world production of ti bike frames is more than a few thousand per annum, which is just a small fraction of the titanium that’s in one plane. Kind of puts our little world in context, really.
Weight for weight, titanium is stronger than steel, but volume for volume, steel is stronger (steel is 70% more dense than ti). So a ti frame can be just as strong/tough as a steel frame, even though it’s lighter. But on the other hand if you fit a ti bolt into a hole designed for a steel bolt, the two bolts are the same size/volume so the ti one is likely to be weaker. That’s not to say that a stem designed for ti bolts isn’t perfectly viable, but the designer may well specify bigger (but still lighter) bolts than he would have done if he was designing for steel bolts.
Titanium is difficult to weld. Only a few repairers in the UK work with ti. If it wasn’t difficult, Argos and the others would repair ti as well, but I believe you need special facilities. What Wikipedia says (anyone know if it’s right/wrong?) seems to reflect some people’s experience of cheap ti frames - “All welding of titanium must be done in an inert atmosphere of argon or helium in order to shield it from contamination with atmospheric gases such as oxygen, nitrogen or hydrogen. Contamination will cause a variety of conditions, such as embrittlement, which will reduce the integrity of the assembly welds and lead to joint failure.”
But I can’t see why anybody would use anything but aircraft grade ti on a bike frame - not to use it is bordering on fraud. And anyway aircraft grade ti tubes aren’t exactly in short supply or exotic or anything. My favourite stat (again from Wikipedia) is that there is 145 tons of titanium in an Airbus A380. That’s just one plane, and that’s quite a lot of ti - it’s the weight of 90,000 bike frames. I’d be surprised if the world production of ti bike frames is more than a few thousand per annum, which is just a small fraction of the titanium that’s in one plane. Kind of puts our little world in context, really.
