Kevindale

I was recently reading a BF thread that was from around 2006 in which people were talking about aluminum frames wearing out or becoming limp -- not cracking or failing, just losing their stiffness and ride quality. And it reminded me that when I first got back into riding, about 10 years ago, I'd heard similar things as a reason not to buy a used bike. But I don't hear that concern anymore, at least when it comes to alloy frames. I don't see experienced cyclists avoiding, say, 20-25 year old Cannondales for this reason.

Was there/is there much validity to this idea? I know frames that are heavily used can suffer from fatigue, but my impression is that it takes pro-cyclist levels of miles and pedaling energy over a fair number of years for this to be an issue. Was this an issue for the early generations of alloy frames, or just push-back from steel frame makers, or a ploy to sell more new frames?

Mobile 155

When they first made aluminum framed adult bikes they tried to make them look like steel bikes with the same sized tubes. It made for a light bike. Those bikes tended to be somewhat flexy. To make aluminum as stiff they thought they had to make it thicker and that added weight. Once they discovered that oversized tubing was both lighter and stiffer the problem more or less went away. If anything people thought Aluminum was too stiff.

oddjob2

If what you say is true, I'd hate to be flying in older commercial jet aircraft. Here is a good discussion.

https://www.bikeforums.net/bicycle-me...-aluminum.html

prathmann

Yes, but that was much earlier than the OP's mention of 2006. Klein made his initial fat-tube aluminum bike as a school engineering project in the mid-late '70s and Cannondale entered the market shortly thereafter.

No reason for the frame stiffness to have a noticeable change over time unless something is actually starting to break. My '89 Cannondale still feels the same as always and if it ever starts to feel less stiff I'll quit riding it and look for a crack somewhere.

DMC707

There are rigorous inspection schedules though based on the number of pressurization cycles the plane goes through,

Granular de-lamination of heavier aluminum support members is a bigger problem than failure of the sheetmetal skin though, But performance characteristics of sheetmetal riveted to stringers and bulkheads is different than relatively thick (compared to sheetmetal). aluminum bicycle tubes welded together

DMC707

I have an aluminum frameset that i have felt this -- it has roughly 15,000 miles on it. It has likely exceeded its original lifespan expectations

People say i am tilting at windmills, - but the frame is dead. It feels like riding a clunky carbon frame thats 5 lbs heavier now. New it felt -- i dont think Zingy is a real word, but it felt zingy- light, fast and stiff

Cant explain it and cant substantiate it

repechage

The "first gen" aluminum frames such as Alan and Vitus were noodles from the get go, at least from my experience.


There were plenty before them but were lower in production volumes and in comparison, not widely distributed.

markjenn

We're getting off-tangent here with the usual discussions of alum fatiguue and its ride quality vs. other materials, but to get back to the OP's question, I think the idea that an alum frame gradually becomes less stiff (limper if you will) or that the ride quality changes over time has been completely and widely debunked, as their is no technical rationale with respect to the material properties why this would happen. It's been tested repeatedly and a used alum frame that has not failed will have exactly the same stiffness and ride quality as a new one.

https://janheine.wordpress.com/2012/...es-going-soft/

To those whose anecdotal and subjective experiences say otherwise, I have no response other than to say that their opinion is anecdotal and subjective.

- Mark

Mobile 155

Not having read the 2006 thread I didn't know what year frames the OP was talking about so I simply tried to cover the spectrum. My 89 Klein is anything but flexy but I had read that early non oversized aluminum was. Not a judgement call only information.

bradtx

Kevindale, In the mid '80s there were some Cannondales that were mis handled prior to heat treating. Most failed quality inspection, but a small number did reach consumers with very slightly bowed (drooping) top tubes. I don't know if this led to any kind of limp rumor.

Brad

DiabloScott

That's what I was thinking - also maybe these folks gained 20 kilos since they bought their Vitus 979 in 1984... yeah, that'd feel flojo.

OldsCOOL

My '88 Criterium Series frame still lights up the road. Awesome response. It most likely doesnt have 100k+ miles but it aint a spring chicken either. You kick it in a sprint you best hang on tight.

Kevindale

This is pretty much what I've thought was the case. Otherwise it just doesn't make sense, from the standpoint of material engineering sciences. I can see components getting worn out and sloppy, and bolts getting loose, but if the frame is losing it's stiffness, it should be on a steep path to failure.

Part of what I was referring to in the original post was years ago hearing a pro bicyclist (a nameless man of the peloton, not a star) on NPR years ago referring tangentially how he hated bikes after he'd ridden them for a couple of years because they felt "worn out," and he would try to get the sponsor to replace them, or get them stolen, so he could get something new. I don't even know what kind of frame material he was referring to, but it always struck me that this must be some kind of a reverse placebo effect -- if you have it in your head that you'll need a new bike every few years, you're going to notice things that confirm it. You basically experience what you expect to experience.

Chrome Molly

Could also be that riders get stronger over time and/or get to comparing the lightly built al frames to modern large diameter stuff.

prathmann

Yes, I remember hearing comments like that quite often in the '70s when essentially all the bike frames were steel - that their frames lost their 'springiness' or 'liveliness' after a couple of years of racing. Never made much sense to me at the time and I figured it was more to rationalize the desire to buy some new bike that caught their eye.

fietsbob

Diameter increase Increases Stiffness.

busdriver1959

[QUOTE=prathmann;18941260]Yes, I remember hearing comments like that quite often in the '70s when essentially all the bike frames were steel - that their frames lost their 'springiness' or 'liveliness' after a couple of years of racing. Never made much sense to me at the time and I figured it was more to rationalize the desire to buy some new bike that caught their eye.[/QUOTE


I was told by a shop in Dallas that my steel RRB should be replaced after about 5 years. It's been 35 years now. I think the guy was misinformed.

Falcon3

Anecdotally, my Cannondale ST400 with 10,000+ miles is far more comfortable (ride quality feels softer ) than my ST600 with under 200 miles. Same tires. Weirdly, the Worn out st400 is still stiff as hell on sprints and climbing out of the saddle.

79pmooney

Gary Klein had been building bikes for several years when I rode his before a race in 1976. According to Wikipedia, Cannondale started their production in 1983 which matches my memory.

Ben

prathmann

Also according to Wiki, Klein built his initial bike as part of an engineering class project in 1973 followed by a few prototypes for industry shows in 1975. Production is listed as starting in 1980. Seems consistent with what I wrote above.

T-Mar

Klein was marketing frames and bicycles prior to the 1980s. The first advertisements started appearing in mid-1976 and I have a road test conducted in early 1978.

Spaghetti Legs 

I would wonder if you could expect fatigue and more flex from those old Vitus and Alan lugged frames. Those were glued rather than welded weren't they? I would expect the bonding to fail before the aluminum.

JohnDThompson 

That a wider diameter tube is stiffer than a narrow diameter tube of the same wall thickness is a basic engineering principle that has been known for over a century at least. The standard-diameter tubes on old aluminum frames was more to accommodate clamp-on components (shifters, front derailleurs, cable guides) designed to fit standard-diameter tubes. It wasn't until bike manufacturers committed to large quantities of non-standard frames that component manufacturers decided it was worthwhile pursuing that market.

JohnDThompson 

Failure of the glue bond happens, but is relatively rare. The ALAN frames in particular were known to develop cracks in the head lugs, e.g.:

vinfix

I think the OP is correct, you'd have to be a pro cyclist putting many miles and a lot of force to cause any measurable fatigue.
Alan's were indeed "screwed and glued", I had one for about 25 years without a problem, though I never raced or put thousands of miles on it. Likewise I had a NOS Vitus I put about 1500 miles on- it was more comfortable than the Alan because of geometry, the fork in particular. It flexed, but not as badly as people make out.