RE: [CR]headset keyed washers

(Example: Framebuilders:Pino Morroni)

Date: Sat, 20 Jan 2007 21:40:37 -0500
To: classicrendezvous@bikelist.org
From: "John Betmanis" <johnb@oxford.net>
Subject: RE: [CR]headset keyed washers


At 08:28 PM 1/19/07 -0800, Scott L. Minneman wrote:
>I spent a bunch of years in physics and engineering courses, but none if
>that is helping me formulate a explanation for a properly fitted and
>assembled headset coming loose in the way Dale describes.

Well, when you jam 2 nuts together there is very little material to compress in the nuts, or material to stretch in the steerer. The most secure way to do it is to overtighten, which you don't really want to do, because it permanently deforms the threads. By having a washer in between, you are compressing the washer and stretching the steerer, thus are able to get more preload before causing permanent deformation. It's the same principle as stretching a bolt within its elastic limit when you torque it. Oh, sure, you can tighten a headset securely with no washer, but you run the risk of damaging the threads over time by doing this. There is a very fine line between too tight and too loose without a washer.

John Betmanis
Woodstock, Ontario
Canada