Carlton Reid on QR safety

On Fri, 17 Feb 2006 09:19:21 +0000, Tony Raven wrote:

Given how often lawyer lips have come up in this and the previous
threads on the topic, there is no chance that anyone has forgotten the
lawyer lips. The intent of laywer lips is not to provide axle retention
for disk brakes, it is to prevent people who don't know how to use QRs
from losing their front wheels.

Correct but by default it should prevent a QR from exiting the fork for
forces many times the highest calculated here for an ejection force.

Sadly not. British Standard 6102-1:1999 (which is based on ISO
4210:1996 but has advanced in some respects) requires wheel retention by
the QR mechanism of 2300N (517lbf) for 30 seconds, but with open QR the
lips have to withstand a load of just 100N (22.5lbf). [Section 9.4.4]



Mike