Chuck Schmidt put it this way: "Is there any difference between a big road sprint in the Giro or Tour with Cipollo pounding down the road using a QR to hold his back wheel or Marty pounding down the velodrome using a nut to hold his back wheel.
Neither slip, so it must be that nobody wants to collide with a QR lever on the track." **********
IMO, yes, there is a difference. Cipo is using vertical dropouts which are not subject to slipping like a horizontal. To add some classic content, many of the classic QR's used steel nuts and steel skewers so they could generate much more clamping force than many of today's aluminum or composite nuts and skewers designed for minimal weight and not ultimate strength.
If I do a bit of mental gymnastics to put this all in perspective (in my mind anyway), the cam closing action on a skewer cannot generate any more clamping force than the yield strength of skewer rod itself. Most skewers are about 5mm in diameter. Assuming the material is equal in yield strength to 4130 chromoly steel, about 75KSI, that gives a potential of yield strength on a standard steel skewer of around 1,610-pounds based on the root dimension of the threads (4.2mm nom.). Since the skewer must clamp both dropouts using a common rod, total clamping pressure is equalized over both dropouts. If we assume the same properties for a 4130 track axle and nut of standard dimensions, 10mm, then the potential clamping pressure is limited by the root dimension of the axle threads (8.8mm) and its ability to resist tightening stresses, preload, and external load. That'd be about 7,000-pounds and since each nut clamps each dropout between itself and the face of the axle, that's 7,000-pounds per dropout. You can give or take a few ksi for stuff I didn't account for, but I think that's pretty close.
Cheers! Don Ferris Littleton, Colorado
-----Original Message----- From: classicrendezvous-admin@bikelist.org [mailto:classicrendezvous-admin@bikelist.org]On Behalf Of Chuck Schmidt Sent: Thursday, March 28, 2002 2:59 PM To: classicrendezvous@bikelist.org Subject: Re: [CR]Track ENDS/Nutted Fasteners
Warren Young wrote:
>
(cut)
> As my mother always said, "I'm from Missouri". We grew up in Toronto. I
was
> confused for many years. I may still be confused about this issue. And no,
> I am not throwing down the gauntlet. But if someone has any emperical data
> on the superiority of QR's they would like to share, I'd be happy to be
> convinced otherwise.
I'd put it this way: Is there any difference between a big road sprint in the Giro or Tour with Cipollo pounding down the road using a QR to hold his back wheel or Marty pounding down the velodrome using a nut to hold his back wheel.
Neither slip, so it must be that nobody wants to collide with a QR lever on the track.
Chuck Schmidt
South Pasadena, Southern California