styrrell wrote:
I don't doubt that it would cost a lot, but nowhere near 100K, and not nearly as overweight as you think. I just isn't that exotic to form and shape metal into complex shapes, even Ti. The Speed concept isn't particularly complex in shape. Given the same molds that are used for the SC, just make male versions and form the Ti sheet around them then weld it up. The weight difference wouldn't have to be any different % than a round tube Ti bike vs a round tube C bike.
I'm not entirely sure that Ti would be much more if you could sell them in the same quantities. Stamping and welding, even for Ti isn't all that expensive, and C requires molds, autoclaves, refigeratiors, pressure, etc.
There just isn't a compelling reason to gear up for Ti monocoques, but no real technical issues.
Styrrell
Ti is a difficult metal to work with, at least in comparison to steel and aluminum. The ductility, the ability to stretch the material, is very low and would make it difficult to bend the material in the way you are describing. That is the first issue. The second issue is that you are going to be doing lots of welding. The welds will not only affect the smooth lines for aero, but are going to be weakest points for both the ultimate strength of the frame and for fatigue. The stress riser of the welded area will necessitate using thicker material than needed if there were no welds. Also the great thing about carbon is that you can easily change the local thickness of the part easily to account for the stress in that area, so you can have the top tube be really thin in the middle and progressively get thicker near the head tube and seat tube. Sure you could possibly do this with Ti by either acid dipping the sheet, machining, or using different thicknesses of Ti sheet along the tube (but this would add even more welding). All of these methods would also mean you male mold would be more complex, also with the male how would you get the seat tube mold out after forming the Ti around it? Even if you do not weld it first, getting the mold out would be an issue with the curves. Unless you made it in a couple separate pieces and welded those together, but that would mean more welds and that is bad.
The real killer in all of this is heat treating your fabricated frame. When you weld the material, the material around the weld will lose the original temper and be much weaker. So you would need to heat treat the frame after the welding is complete to get the material back to the high strength condition. But you have these very complex tubes and I will guess that all of the tubes have different thicknesses in order to optimize the weight, but that means that they all heat up and cool down at different rates. So they expand and contract at different rates. That makes it very complicated to heat treat the frame without causing distortion of the frame.
This is just a sample of why carbon is such a great material for bicycle frames. You can just optimize the lay up for the specific loads. Look up the material properties of Ti and carbon fiber, then look at how many compromises a Ti frame requires. Do you really think it would lighter, more aero, or cheaper? Sure it would look great unpainted, but I fail to see a real advantage.