Thanks for the responses. And for the pointer to Waltly. I do see that they have a double butted options for most tubes, actually, and their form gives me at least some ideas on tube diameters. Yes, I will consult with the builder, but wanted to get other people's opinions first. On the topic of wall diameter & thickness, are there general suggestions with respect to the relationship between the two (specifically for Ti)? I understand that bigger is generally better, but are there sweet spots if I, say, pin diameter or tube thickness to a certain (personally chosen) upper bound? E.g., browsing the forum I stumbled over the idea that wall thickness should not go below 1/50th the tube's diameter. Is there a point of diminishing return with respect to increasing wall thickness for any particular diameter? Any analyses you could point to?
> you are saying that only the toughest frame will suit you, anything less won't.
It's not an ideal formulation and perhaps I should have left it out. I kind of know what the frame will be subjected to (which realistically is unlikely to be that much in absolute terms; certainly not on a regular basis), but it is hard to convey in words. I am sure that picking a specific super strong Titanium is unnecessary for my use case, especially if it comes at a steep increase in cost. But perhaps a good way of getting to a useful answer is by way of comparison: geometry aside (which obviously has an impact; but for the sake of argument we shall assume equality) let's say I want to match the strength of a given 7005 aluminum alloy tube. Are there general guidelines? If I match diameter and thickness of an aluminum tube in Ti the result should be stronger (and heavier). How small could I go to come out roughly equal (I do understand that different materials react differently to different kinds of strengths, I am mostly looking for rules of thumb).