Road Cycling - Differences in Aluminum

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smurfy
05-30-04, 11:03 AM
Okay, I think this might be a good forum for this topic!

As many of you already know, not all aluminums are the same! Cannondale has, of course, heat-treated 6061-T6 alu frames and Santana and some others use 7000 series alu on thier frames because they say it's better than 6061 and it doesn't have to be heat-treated. I've noticed that really light competition handlebars are 2024 alu but I never have seen a bike frame made out of this material. Why is that? It's because it's too brittle or something?

This has been getting my curiosity up recently because part of my job at work is cutting up raw steel and aluminum for use in the weld and machine shops. We have alot of 6061 and 2024 alu stock, some of it in big heavy chunks that I can hardly lift. We also have 6262-T9 aluminum (which we hardly ever use!). Why would that not be used in bicycles (or is it?). Any metallurgists out there?

What's good-better-best?

I think I might save my steel questions for the SS/FG forum!

Poppaspoke
05-30-04, 12:12 PM
Modern high-end aluminum tubesests are drawn paper-thin and precisely engineered for the load they are designed to carry. A lot of people are unhappy with this trend...there's not a lot of data on the longevity of these frames, and how dent-resistant could such a thin piece of metal be? Interestingly, Reynolds new X-100 aluminum/lithium tubeset (Jamis Xenith uses it) goes the opposite direction: smaller diameter, thicker tubes (like steel, but lighter).
khuon
05-30-04, 12:15 PM
This topic has been discussed in recent threads.

Here's a couple...

http://www.bikeforums.net/showthread.php?t=53270
http://www.bikeforums.net/showthread.php?t=51530

khuon
05-30-04, 12:17 PM
Interestingly, Reynolds new X-100 aluminum/lithium tubeset (Jamis Xenith uses it) goes the opposite direction: smaller diameter, thicker tubes (like steel, but lighter).

That reminds me of the early Trek 6000 and 8000 series MTBs I test rode back in 1990. They used thick-walled small-diameter aluminum tubes too but they felt pretty noodily when climbing. I went with a 4130 bike instead. Many aluminum bikes from the early 1990s used similar tubes. Some went the box-section monocoque route though. Cannondale of course promoted the whole concept of "oversized" diameter thin-walled tubes which caught on during the mid to late 1990s and is what most aluminum frames today tend to use.