In brief: between a standard quick-release skewer and a bolt-on skewer, which will provide greater clamping force?
Modern bicycle wheels are held in place by clamping skewers that run through hollow axles. The typical "quick release" design has a built-in lever on a cam that you close with you hand to secure the wheel, like this:
If you prefer not to have the quick-release mechanism on your hub for whatever reason, it's possible to retrofit your axles with "bolt-on" skewers which forego the cam and lever for simpler hex heads:
The torque spec for bolt-on skewers is generally 7 N-m, while Shimano recommends 5.0 - 7.5 N-m tightening torque on their quick-release skewers.
My question: How would these torque values applied through their respective systems (7.5 N-m through a cam versus 7 N-m through a threaded fastener) compare? Which would likely result in a higher clamping force (if we're assuming proper lubrication with no contamination, etc.)?
Generally, people seem to believe the bolt-on design clamps down better, but I've seen some people insist the opposite is true. Conventional wisdom in the bicycle world is notoriously dodgy, so I was hoping to get some expert insight.