Quote Originally Posted by cutterjohn View Post
What I'd like to see is a definitive study of weight, durability, and shock absorbance for equivalent frames in Ti or Al. Then, we would have either a resource for saying Ti doesn't really have an advantage and people like me could stop worrying about how to get it covered, or it does have an advantage and people like me would have hard evidence to back up our insurance claims.

In my previous life, I was a serious bicycler. Though I never had the $$ to get a titanium frame, it was widely understood that Ti frames were more forgiving and springier than Al frames. This is in spite of the fact that most of the cushioning comes from tire type and pressure, saddle type, and frame geometry (e.g: fork rake). Even with all these variables, Ti made a huge difference in how the bike punished you over a long ride. Metallurgically, it was also understood that Ti doesn't fatigue over time like Al does, and so lasts longer. What I don't know is how much of that is at play in a wheelchair frame, given the points you make about tube thickness, etc. That's why, again, I'd like to see a serious study. A statement like "A 1.25" tube ZR frame doesn't flex" is fine to make, but it would be better to have something to reference with it.
Agreed. Just because, try as I may, I couldn't get a 1.25" ZR frame to noticeably flex, doesn't mean someone heavier or stronger than me couldn't. So many variables. The forces a bike, at velocity, are under are way stronger than a wheelchair ever reaches, so a wheelchair specific set of objective data would be nice.