DannoXYZ,

You're just so hostile - or is it just Macho? Anyway, given your superior engineering knowledge, why don't you show us the calculations and specification of your 2" twist. Without that, all your engineering talk is just spew.

Nothing about the picture shows where the flex is occuring. Look closely at the top tube, its moved. That the ends of the bars are in different positions proves nothing. It is true that a larger diameter stem will be stiffer, all else being equal. Rarely is all else equal, but that ignores the question of how much stiffness is necessary.

You question the discussion of why? Why is what its all about. All the differences that you note for people to chose between, are all about why. Why should someone chose one over the other?

Lots of stem breakage at your shop, eh? Guess I'll avoid it. That's not common with well maintained bikes. Yes, some racers, on the edge, break parts of all kinds. They are generally exploring the engineering limits of the parts they use. Usually, its unncessary - like Hincapie's broken steerer. That is, a couple of extra ounces on a bike to make sure it doesn't break is not only good insurance, it won't hurt performance. No one that I have read has been able to extract, from real world performance, the benefits of having one of the lightest bikes in an given contest. Forget the theoretical calculations of energy to raise a gram a meter in elevation. Real world results don't mesh with the calculation.

One other point, the ease of changing bars is another red herring. To change bars, one has to remove the brake levers/shifters, bar tape/pads/grips, & accessories regardless of the stem type. If the need to thread the denuded bar through a clamping stem slows down the change operation by any significant amount, then the mechanic isn't very good. IMHO

So, we get back to nits. The issue isn't whether the stem is designed for a threadless or threaded stem, its whether the rider gets out and uses it. People blowing theories about whats best or right scare too many people away from good experiences on a bike. Which was my point all along.