Mitch Harris wrote:
> This is how the history of lugged bicycles is being told on the
> Tandem@Hobbslist. Strange.
> From: Arlyn @ Superior Tandems <arlyn@superiortandems.com> Date: Jan
> 17, 2006 7:25 AM Subject: [T@H] was Pedals now lugged forks? To:
> Multiple recipients of list <tandem@hobbes.ucsd.edu>
>
> Folks,
>
> Someone pointed out to me that not everyone knows what a lugged steel
> = fork is and why they frequently fail. These went out of
> popularity in the = 80's because of there terrible rate of failure.
> These are brazed steel = forks that the crown is a lug and the steel
> fork blades were brazed into it. = The rate of failure of the blades
> at the lug after XYZ number of stress = cycles was pretty much 100%
> because of the flex on the blades were they entered = the lug.
> Maybe some of you engineer types care to elaborate?
>
> Jobst Brandt does a better job of describing it at
>
> http://yarchive.net/
I think the key things to note are 1) Jobst does *NOT* claim "pretty much 100%" failure rate of steel forks, as implied in Arlyn's message; and 2) without specifying the number and degree of stress cycles, Arlyn's claim of 100% failure is meaningless. Any part will fail eventually under some extreme conditions. Without specifying what those conditions are you cannot make any judgments about the durability of the steel forks.
--
-John Thompson (john@os2.dhs.org)
Appleton WI USA