Originally Posted by
smd4
Aside from a cleaner look, why does the inclusion of a cover make an internal QR work better?
Originally Posted by
grumpus
It's not the fact that it's enclosed that improves the action, it's the smaller hardened steel cam as opposed to a larger aluminium and plastic mechanism that gives better mechanical advantage and strength.
That makes sense as well as someone who mentioned steel vs. aluminum or titanium shaft/spindle. I don't really know, but always assumed that the cam design was somehow mechanically better at applying more clamping force? An engineer might be able to explain it. But in the case of my horizontal dropout bike, it does indeed apply more force and keeps the wheel from sliding into the left chain stay. But I must say that it's not really easy even with the external cam - I have to really torque down on. But I could never get the external cam type tight enough no matter how hard I tried.
I think the reason the external cam ones are so ubiquitous is that they can be lighter, maybe cheaper to manufacture, and do work fine with vertical drop outs.