Re: [CR]Broken cranks


Example: Framebuilding:Tony Beek

From: "jerrymoos" <jerrymoos@sbcglobal.net>
To: <classicrendezvous@bikelist.org>
References: <40258DC0.B0C612CF@earthlink.net>
Subject: Re: [CR]Broken cranks
Date: Sat, 7 Feb 2004 20:43:16 -0600


This demonstrates another fallacy in the myth of Campy superiority. Campy cranks were acknowledged to be made of harder alloy than Stronglight or TA. Did this make them better? Well, they wore less and showed less wear after the same number of miles. Better, right? Maybe not. The harder Campy alloy was also more brittle, so they suffered brittle stress cracking, notably at the junction of spider and right arm or at the pedal hole. This type of failure is almost unheard of with the softer Stronglight or TA cranks. Of course TA and especially Stronglight arms, being softer, had a greater tendency to seize up on the axle. But this could be prevented by applying a very light film of grease to the axle when installing them. The familiar Campy pattern - great quality control, stupid design.

Regards,

Jerry Moos
Houston, TX


----- Original Message -----
From: "Chuck Schmidt"
To:
Sent: Saturday, February 07, 2004 7:15 PM
Subject: [CR]Broken cranks



> http://pardo.net/pardo/bike/pic/fail/000.html
>
> http://pardo.net/pardo/bike/pic/fail/FAIL-008.html
> ============================================================================ =====
> With the text
>
> The Campy Only Retro Bike's left side crankarm gave up the ghost on a
> nighttime ride on May 31, 2001. Your C-O webmaster ended up flying over
> the front of the bike, shattering a helmet and getting a bit of road
> rash. A word to the wise: old Campy parts can break! Our crankarm showed
> no signs of damage or fatigue whatsoever, right up until it failed, but
> it's a good idea to keep an eye on critical parts like these on your own
> bike. (For an example of what to look for, check out this photo of a
> stress crack on the right-side crankarm . . . this has of course been
> taken out of service!
>
> http://pardo.net/pardo/bike/pic/fail/Dscn2410_640.jpg
>
> The above says there were ``no signs of damage ... until it failed'',
> but note that in many cases there are cracks showing before the part
> fails. You have to know what
> to look for and you have to look regularly so as to find the cracks
> between their onset and the final failure. Clean the cranks and examine
> them under bright light. Jobst Brandt reports he has broken dozens of
> cranks, checks his cranks monthly, and has caught them when cracked but
> not broken through in all but two cases.
> ============================================================================ =====
>
>
> Chuck Schmidt
> South Pasadena, Southern California

>

> .