Aluminium fatigues based on the number of cycles and loads. The fatigue failure starts as a microcrack, then fairly rapid crack growth proceeds. Therefore the commonplace warning to inspect for cracks on old aluminium parts.
The parts are not "weaker" after use. If cracks have not initiated the parts will test just as strong at year ten as new.
If an alumium alloy is very hard like a 7075-T6 component it can crack through rather quickly. So typically high strength alloys can fail more suddenly when they do go.
Joe Bender-Zanoni
Great Notch, NJ
> *famous* Lou,
>
> I too read that and scratched my head.
>
> And one can only imagine that a super-conservative company like nitto
> would make bars that last longer than many others.
>
> Recently, our shop has seen a rash of modern cinelli bars opening like a
> can-o-beans (at the stem) after only a few months! (yikes)
>
> Grant McLean
> Toronto.Ca
>
> O \O/
> _< \_ _< _
> (_)>(_) (_)>(_)
>
> In the latest Rivendell Reader, #30 (I'm sure you are all subscribers,
> right?), Page 14, in an interview with the President of Nitto, the
> question is asked about whether aluminum handlebars should be replaced
> every five years, even if they have not been crashed. The answer says
> that if you have an aluminum handlebar that is ten years old and never
> used, that it will be "significantly" (quotation marks added by me) weaker
> than when it was new. Anybody know why this would be? It doesn't make
> sense to me, but then, I'm no metallurgist, just a rocket
> scientist.......Lou Deeter, Orlando FL