Originally Posted by
mtnbke
What else to avoid? Any vintage bike with an vintage alloy handlebar. Almost nothing can be as catastrophic as a complete loss of steerage on a bike at speed. Aluminum bars should be treated as 'schedule replacement' components on your bike just like your chain, rings, and cogs. The aluminum fatigues and after so many cycles they will fail. Its isn't a matter of if, but a matter of when.
Leonard Zinn says replace after four years of use, or one year of use if racing. Zinn has a background in physics, is the tech guy at Velonews, and builds his own components and bikes out of steel, aluminum, magnesium, and ti. Trust his opinion, he isn't just trying to get you to buy more bars.
Any bar that has hit the ground, either the bike falling over, or laying the bike down should be replaced in my book. The small diameter of vintage bars makes them especially suspect considering modern oversized stuff (less prone to failure).
Bull.
My view as a cyclist:
I have never seen an aluminum alloy handlebar fail catastrophically in such a way as to result in a "complete loss of steerage". I've seen bars damaged... and even break... but you're just trying to scare people with talk of losing steering control at speed.
My view as a professional engineer:
It's all about failure modes. Aluminum alloy does not fail suddenly and catastrophically except when manufactured in a casting process. How many cast aluminum bars have you seen? An alloy handlebar under normal use will fail by bending or cracking, hence giving the user a warning that a total failure is coming. If your handlebars are bearing such a load that they fail so suddenly that you have no warning, then you're doing something wrong.
I don't care what credentials that Leonard Zinn has attached to his name, I think he's full of it on this issue... and I've been an engineer for almost 30 years. Does that count?