No. the fact that it's a headset doesn't really matter. Anywhere that you tighten a threaded fastener, the more of the "bolt" that is available to stretch, the less chance of it (or the nut) backing off. The keyed washer provides a little "length" and it also gets compressed a slight amount. As someone mentioned already, The fact that it's keyed is irrelevant, although it helps somewhat, because you can tighten the locknut with just one wrench with a little trial and error. I've done that with headsets when I couldn't find another wrench, but still use two cone wrenches for hubs.
John Betmanis Woodstock, Ontario Canada
At 09:01 PM 1/20/07 -0600, Robert Clair wrote:
>... is this because it is a top loaded force ? what about side loaded
>forces like pedals on cranks ? hub shells outside of axle bearings ?
>anyway appreciate this dicussion very much.
>yours,
>r clair
>alexandria, va 22308
>
>----- Original Message -----
>From: "John Betmanis" <johnb@oxford.net>
>To: <classicrendezvous@bikelist.org>
>Sent: Saturday, January 20, 2007 8:40 PM
>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