Aluminum Frame Longevity

Discuss light weight issues concerning road bikes & parts.
User Name
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by User Name

I've been racing, mashing, thrashing and crashing (not that much :)) aluminium frames for over ten years, and I've only cracked one, which was a cheap 1999 Specialized Allez Comp, which cracked under the bottom. In that time, I've weighed anywhere from 77kg to 90kg.

I admit, the only super-light (relatively) frame I've had is an old CAAD8, which is 1265g (58cm), so it's not like I've been thrashing very light Columbus and Dedacciai frames for years.

Having said that, aluminium frames obviously do break. I knew an ~80kg guy who cracked 3 of the old alu Giant TCRs about ten years ago, all through the down tube. I knew another slightly big-ish guy who cracked 2 chainstays of 2 Cinellis made from the light Columbus Airplane.

If you're concerned, one huge benefit of alu is that, as far as I know, in most circumstances, cracks can be spotted well before they develop into a catastrophic failure. So, it's wise to regularly inspect your frame for obvious cracks or suspicious paint cracking. Paint that's moved or separated over a crack usually looks like a squiggly line, rather than a normal scratch.
That's how I found the crack in my Specialized: the paint 'scratch' looked suspicious, so I sanded it off and saw the fine crack.

by Weenie


boolinwall
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by boolinwall

What makes you think that U107 is 6000 series aluminum? I was always under the impression that Dedacciai shied away from 6000 series alloys. As did Columbus.

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kgt
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by kgt

Rick wrote:Aluminum does fatigue....in theory.
In practice: don't flatter yourself. Ride.

+100

mickey
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by mickey

boolinwall wrote:T Unless you have a heat treating facility available to you. You can forget about "safely" repairing 6061 or other 6000 series alloys.



It really depends on what the issue is that you're dealing with.

example- we moved the brake bridge up on this Caad10 the other day:
Image

Other 6061 repairs that don't really require heat treat include stuff like fixing cracks at dropouts, chainstay cracks due to chain gouging, etc.
A main tube replacement is going to require heat treat though.
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DMF
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by DMF

Very sligthly OT, but still, is it just me or can aluminum frames tend to "go soft" after a few years if pushed really hard. I'm a bit of sprinter, masher, high watt-spikes, type of rider (rear tires don't last long). What I mean here is that, can they loose that responsive 'zing' in the rear triangle and start feeling a bit, well, mushy...?

Ofcourse I realize that this, if it even is the case, might depend a bit on riding style...

...the feeling is driving me mad, had it happen before too after similar amounts of use. Am I loosing my mind, or is this actually happening?

boolinwall
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by boolinwall

Nope. You're not losing your mind. Aluminum lacks memory. Meaning that it doesn't snap back into place the same way steel or titanium do. It also doesn't deflect the same way the other two metals do. This is what gives aluminum it's stiffness advantage over damn near every other material out there. It will, however, soften over time. Mind you, for most people who aren't a protour sprinter, we're talking years and years. It'll also depend on the quality of alloy and heat treating. Better quality alloy and heat treating = better memory.

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DMF
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by DMF

Ahh, THANK YOU! Very glad to hear I might not have lost my last marble just yet... maybe time to seriously start thinking of a new frame for next season...

User Name
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by User Name

Yeah, as far as I know, it's a myth. The only time they'll feel softer is right before they're about to break. :D

I have a couple of 2-bit theories as to why frames may feel less stiff over time: :D

1) Most of all, we simply get used to a frame's 'zipp', and it stops blowing our socks off over time. One way around this is to not ride it every day (ride a crappier bike on some training rides), or keep upgrading, like a lot of the guys on here. :) I usually save my best bikes for races and some group smashfests, partly to make sure my best parts will always be running well when I need them, and coz it's a great boost to get on your most fancy bike if you haven't ridden it for a week or 2.

2) Different wheels flex more than people realize, so changing wheels can dramatically change the ride. Also, some wheels can lose spoke tension over time.

3) Weight gain. If you suddenly have an extra 5kg+ stomping down on the bike, it's gunna feel flexier. A few years ago, I dropped about 8kg, and my bikes and flexy wheels suddenly felt stiffer.


Good theories? Yeah! Ha
Last edited by User Name on Sun Jul 21, 2013 7:09 pm, edited 1 time in total.

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DMF
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by DMF

I ruled out the wheels bit though, also went there as a first thought. Haven't gained weight. And I would've liked to think I've just gotten used to it, but thing is the bike has started doing some pretty scary noodle-moves during sprints, it really wanders off, or the rear end just steps out of line sideways, from time to time, sometimes with a bit of a scary "kick" as it "steps back".

It's not huge, but it's definitely there, and it's definitely new. Or I'm slowly loosing my mind...

...or, I'm just getting stronger, hahaha

User Name
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by User Name

Yep, you're getting too strong. :D

It's not busted? No carbon stays coming unbonded?

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DMF
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by DMF

Yeah, I too wish I was turning all green and ripping thru my shirts :)

I've looked as best I can for any hints of cracks but found non. The frame is (double butted 7005) aluminum all the way, fairly common design. No bonds, no mono seatstay/chainstay junctions and very standard dropouts. It's also a bit of a porker at some 1.640 grams...

But it's a cheap'ish Kinesis Racelight so it might be an inferior quality alloy compared to the pricier offerings with brand name Italian tubes and what not? Regarding metal memory, and so forth...

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by User Name

DMF wrote: It's also a bit of a porker at some 1.640 grams...
..
1.64g is pretty light :D

eh, there's nothing wrong with that. I've had several aluminium frames around the 1550g to 1650g mark (I've been told before that I don't belong on here :D).
My 58cm Dedacciai 7003 was about 1560g, my Dedacciai T6 Energy (old Ciocc) is about 1580g; my wet day bike (Norco, Easton Elite) is around 1660g; etc, etc.... my alu Soloist is 1425g. I had a BMC Streetfire, which was 1540g. I also have a cheap alu Allegro which is nudging 1700g.

boolinwall
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by boolinwall

The stiffest frame I've ever ridden was a GIOS New A-90. It was listed at 1400 grams. Yeah,, maybe in the smallest size with no paint and no dropouts in place. It was over 4 pounds. Stiff as heck, tracked like a dream and is still the best climber I've ever ridden. So let's not put too much weight into weight.

User Name
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by User Name

Hmm, interesting. I've always loved those

by Weenie


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DMF
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by DMF

This is a 51cm ST/53,5cm ETT frame though, the 58cm ETT equivalent is in the 1.800+ grams range... Not that I'm concerned though, I like my porky little girl, which would make it a shame to retire her :)

But weights aside, I reckon there is some truth to the quality of alloys used, that might contribute to the frames fatigue, or time before it goes soft, or is there not? Is all 7005 created equal, for instance?

I would regret to spend three or four times the cash of this one (say a Caad or Allez) and only get three good years out of it... That's an individual number ofcourse, but seeing as my case is my case so...

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