Jerry Moos wrote:
>At the risk of somewhat disagreeing with the esteemed Mr. Brown, I
>do not follow his advice to automatically replace AVA stems. These
>stems have been known to fail, but then Campy NR cranks were known
>to crack at the junction of right arm and spider, and I know of no
>one automatically replacing all NR cranks just because of that. As
>discussed here many times, all aluminum components are subject to
>fatigue stress cracking and therefore will theoretically all
>eventually crack if used long enough, although long enough in some
>cases may be several human lifetimes.. I've personally not had an
>AVA stem fail, but I have found cracks in AVA bars and prompty
>removed them from service.
>
>Also, I believe the AVA stems Sheldon warns about are the "faux
>lugged" type. This type of stem was used by virtually every
>significant French manufacturer in the late 60's and early 70's.
>What appear to be identical stems can be found not only marked as
>AVA, but also as several other French brands or with no brand at
>all. Therefore, I'm not at all sure AVA actually manufactured the
>stems in question. Until someone reports actually witnessing these
>being manufactured at an AVA factory, I'm inclined to believe that
>one French company, possibly one we never heard of, manufactured
>these and marked them with the brands of the companies distributing
>them, including AVA and all the others.
>
>So to me it makes no sense to avoid AVA stems unless one is also
>prepared to avoid all alloy stems of the same design. Now if you
>want to be cautious, maybe avoiding them all would be a good idea.
>Personally, I think this is overly cautious, since the only sure way
>to avoid fatigue stress component failures is to never use any alloy
>component. I do think one should inspect alloy components regularly
>for cracks, particularly those with reputations for cracking, like
>"faux lugged" stems, AVA bars and Campy NR/SR cranks. In addition
>to the AVA bars, regular inspections have allowed me to detect
>cracks in a couple of Campy cranks and remove them from service
>before a potentially dangerous failure occured.
OK, I've revised the section at http://sheldonbrown.com/
I was working in a couple of Cambridge, Massachusetts shops during the mid-70s Bike Boom, first the Bicycle Revival and later the Bicycle Repair Collective (Now known as the Broadway Bicycle School.)
My shop wasn't a Peugeot dealer, but we did have Mercier and Jeunet among other brands, and saw lots of Peugeots for service as well. This was when the UO-8 was selling for $87.50 and the PX-10 for $158.
At that time there was considerable scuttlebutt about AVA stem failure, it was a fairly well-known phenomenon among cyclists. These failures were on relatively new bikes.
It's possible that the failures resulted from some isolated casting defects and that all of the bad ones have already busted, so only good ones are left.
It's also possible that the failures were subsequent to folks spreading the clamps to allow the installation of bars with a larger clamp diameter than the 25 mm French size that was stock. Lots of AVA _bars_ got replaced because they bent pretty easily, and back then there wasn't as good an understanding of the technical details of interchangeability. Wouldn't surprise me if some folks even tried to install 26.4 Cinelli bars in these stems, wiht predictable results.
So, it _may_ be that the remaining AVA stems are safe to ride with the stock handlebars...but, we all have seen 30 year old bikes with only 10 miles on them, ridden until the first flat tire then put away...
If you're a light, gentle rider, not prone to sprinting or out-of-the saddle climbing, you may be perfectly safe with a 30 year old AVA stem...but then again, you might not be.
Sheldon "Erring On The Side Of Caution" Brown
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| There's nothing like not being dead |
| to improve a fellow's outlook. |
| -- Michael Flynn |
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