Re: [CR] Comment on the crank arm break please - Origin of Break

(Example: Framebuilders:Mario Confente)

In-Reply-To: <20100126223455.AB92919D8D@ug6.ece.ubc.ca>
References: <20100126223455.AB92919D8D@ug6.ece.ubc.ca>
Date: Tue, 26 Jan 2010 20:23:36 -0800
From: Rob Hawks <rob.hawks@gmail.com>
To: donald gillies <gillies@ece.ubc.ca>
Cc: classicrendezvous@bikelist.org
Subject: Re: [CR] Comment on the crank arm break please - Origin of Break


Don, et al,

The cranks marked this way: 170 STRADA (1) <- 1 (one) inside a circle.

On the cracked surface, the light colored part is very rough, the dark part is very smooth (relatively).

rob hawks richmond, ca

On Tue, Jan 26, 2010 at 2:34 PM, donald gillies <gillies@ece.ubc.ca> wrote:
> It would be good to know the date-code on the back of this crank, can
> you please post it, Rob?  <x> is a 1970's year, (y) is an early 1980's
> year, [11], [22], [33] are 1985,6,7.  There are some other codes but
> not for this crank, I believe.  If it's a very early crank (pre-BMX)
> we can probably guess that it was anodized in the after-market.
>
> 1970's campy cranks had the flutes milled into the crank arms.  I have
> seen some later cranks that had the flutes forged into the crank arms.
>
> It seems possible that the crack originated from the very tip of the
> milled flutes of the crank.  This was either the starting or the
> ending point of the milling drill.  If this area was not carefully
> polished at the factory, before anodizing, it could have left a
> scratch or a crack that could possibly grow later in the life of the
> crank.
>
> Personally, I think the actual cause was the crankset reacting in
> revulsion to the clipless pedals, but that's just the retro-grouch in
> me ... :-) :-)
>
> - Don Gillies
> San Diego, CA, USA