Performance and Weight of steel - vs. – aluminum 29”

[feel the light]

I am sure Semach's comments are accurate. I just wanted to note one of Ti's weakness's, as a material, is it's lack of resistance to twisting. Despite being gram for gram stronger then steel in other respects, Ti lacks torsional rigidity.
Because of this unfortunate fact, heavy parts on unlimited budget factory race motorcycles, such as the crank shaft and transmission shafts, are always made from steel. In these applications, resistance to twisting is vital, and gram for gram, normal steel is stronger then Ti in torsional rigidity.

[joemarshall]

Originally Posted by semach.the.monkey

I have only had one aluminium frame, which was the Schlumpf frame. I didn't swear by it, I swore at it! So, maybe I'm not the best person to answer your question, but the thing I noticed with the ali frame was that it would twist under torque, particularly going up a hill. My new frame, however, is titanium, which I guess is more steel-like but without the weight overhead. That doesn't flex at all. It is very very rigid, and that translates to a much more precise ride with no twisting under torque.

That's probably not to do with the frame material, that's to do with the poorly designed frame - that frame is super twisty because it's made out of such lightweight parts. It's massively under-built for unicycling. Which I guess is why it is quite light, but does mean it has several problems that a £20 nimbus frame doesn't have.

You can see it flex by pulling the brakes and watching how much the frame flexes - which isn't the case on a KH frame, or even my hacked together nimbus brake mounts.

Joe

ps. I dunno how you know about torque going up hill anyway?!!

[semach.the.monkey]

Originally Posted by joemarshall

ps. I dunno how you know about torque going up hill anyway?!!

I read about it in a book once and thought it sounded cool!

As I was typing that, though, I meant to imply that it was more to do with the poor frame design, but actually that didn't really come across. But as that is the only Ali frame I've owned, I can't honestly compare it to other ones.

STM