Road Cycling - Durability, Lifespan

I know the basic durability and characteristic feel of the basic frame materials (steel, carbon, aluminum and titanium). I have a question about how many miles a frame made of each of these would be good for (w/ the exception of titanium of course). I guess I could further clarify by limiting this to higher-end frames (i.e. frame > $2,000). I'm sure there is no deadset range but a nice ballpark figure would be great.

A lot.

I know the basic durability and characteristic feel of the basic frame materials (steel, carbon, aluminum and titanium). I have a question about how many miles a frame made of each of these would be good for (w/ the exception of titanium of course). I guess I could further clarify by limiting this to higher-end frames (i.e. frame > $2,000). I'm sure there is no deadset range but a nice ballpark figure would be great.

Good question, but I don't believe there is any way to answer it, since loads and strength vary all over the map. I'd say fatigue strength of a frame is more a function of the frame weight, tubing dimensions, wall thickness, and build quality than the basic materials. I don't think Ti is an exception here....it fatigues and breaks just like anything else.

As far as data, the German EFBe is the only independent agency I've seen that is doing fatigue testing to a standard protocol:

http://damonrinard.com/EFBe/frame_fatigue_test.htm

build quality and methods will affect this, as will rider weight, riding style, terrain etc.

Good question, but I don't believe there is any way to answer it, since loads and strength vary all over the map. I'd say fatigue strength of a frame is more a function of the frame weight, tubing dimensions, wall thickness, and build quality than the basic materials. I don't think Ti is an exception here....it fatigues and breaks just like anything else.

As far as data, the German EFBe is the only independent agency I've seen that is doing fatigue testing to a standard protocol:

http://damonrinard.com/EFBe/frame_fatigue_test.htm


That is a great article- this thread should be combined with that other thread on frame flexibility.

The article is a bit old so it would be great if they did a newer test but it basically matches the results of Litespeed's torture tests.

It's worthy to note to any Merlin owners- Litespeed now makes Merlin bikes (in the test above, I believe Merlin was seperate) and the construction method is slightly changed so it would be good to retest that, for example.

For latest results, check out the link to the 02/2004 update on the homepage:
http://www.efbe.de/ehomepag.htm

Note that only manufacturers who pay to have their frames tested and allow their results to be published on the website are listed. I'm not familar with some of the Euro brands, but have to appreciate the fine CAAD7 performance. (No, I don't own a C'dale either).

I think the fact that we don't see frames failling left, right and centre is testament to the fact that most product designers and engineers do a fairly good job - or at the very least they conform to standards.

I think the question is, is "How many frames do the top 100 riders in the world go through each season?" This is the best real world testing, although even that's hardly indicative of the riding 99% of riders of Brand X will do, and something no company will ever publish.

So it begs the question - "Is it even relevant?"

I think if you're a privateer racer, do 600kms a week, ride every day, race every weekend kind of guy, it's an issue for you. Otherwise, appart from being hard to qualify, it's hard to judge relevance.

What I do know for sure is that some materials/designs are more prone to fatigue cracking than others, but overall, I believe fit and comfort should be more of a concern than some misguided perception of longevity.

The consumerist nature of our mentality means that most frames will last for most of us well into the zone where we'll be upgrading simply because we want a new frame, not because the frame is broken past it's used by date.

Additional :

After re-reading those EFbe tests, you can conclude a few simple things. Firstly, the tests are old, and do not include any modern TIG'd steel or titanium bikes, so drawing conclusions about them would be wrong. Secondly, apart from the lugged steel bikes breaking in the same spot ( except for the Fondriest ), the next rung of bikes broke at shifter bosses, internal cable routing spots on the down tube, and very obvious stress riser spots. This is why you see modern titanium bikes with bosses on the head tube, and oversise downtubes compared with frames from the mid/early 90's etc.

How old could the caad 7 be?