Bicycle Mechanics - Aluminum: wear out?

A bike salesperson told me that aluminum frames eventually wear out, or become dead. Does this happen and what does it mean?

A bike salesperson told me that aluminum frames eventually wear out, or become dead. Does this happen and what does it mean?
Yes it does. An AL frame can and will eventually feel less responsive or "dead" usually this happens after several years of riding. A general rule of thumb is five years though there will soon be plenty of people here to dispute this.

What do you mean less responsive and dead

A bike salesperson told me that aluminum frames eventually wear out, or become dead. Does this happen and what does it mean?

I put that in the same mental box with worrying about my steel frames rusting away or feeling assured because I can have a tube replaced on my lugged steel frame. I'm sure that all three things happen but, a guy my age probably won't live long enough for it to happen to me. All of my bike frames have always lasted longer than I really wanted them to last. After awhile bicycle frame designs evolve. Rear dropout spacing changes or headset sizes change or I just feel like I want something new.

Incidentally, that comment about aluminum frames losing their "feel" in some period of time - I can remember when exactly the same comment used to be made about steel frames. Back in those days people also said they didn't like aluminum frames because they weren't stiff like a good steel frame. If you live long enough some of these old bikers tales are going to change. Then you get to laugh at the guys who keep repeating them.

It means he'll make more money if you buy the bike that doesn't have the Aluminum frame.

Yes it does. An AL frame can and will eventually feel less responsive or "dead" usually this happens after several years of riding. A general rule of thumb is five years though there will soon be plenty of people here to dispute this.
That's nonsense.Aluminum will eventually fail from fatigue. Design enginers know how aluminum works and design around it. Frames, unless ultralightweight are designed for several lifetimes of use. And, it doesn't go dead, it just breaks.

A bike salesperson told me that aluminum frames eventually wear out, or become dead. Does this happen and what does it mean?It means the salesperson is a moron and knows just enough drivel to regurgitate a few chunks.

One of the big complaints about aluminum is it's too stiff. "Responsive" and "lively" are terms you hear when people are talking about high-end steel or TI frames.

I dragged an ancient Raleigh "technium" alu frame out of the trash and built a retro-rocket to ride while my new bike was in the lay-a-way. Thing must have been 20 years old; worked fine.

I have a 12-14 year old Giant Farrago with Al frame (I'm guessing the age, it has an early 90s date stamp on the stem) and a new Giant Sedone with Al frame. Besides the different size issues, these feel the same to me.

A bike salesperson told me that aluminum frames eventually wear out, or become dead. Does this happen and what does it mean?

It means he wants you to spend more and buy carbon fiber or titanium. :)

My aluminum bike is 19 years old and has >50,000 miles on it. It is not less responsive or "dead".

when I got my al GT track bike 6 yrs ago many people told me it was going to break soon. Since then i put 35,000 miles on it on nyc streets. still fine after couple falls.
Yes they want you to buy more expensive frame. Carbon sucks
:p

It means he wants you to spend more and buy carbon fiber or titanium. :)

My aluminum bike is 19 years old and has >50,000 miles on it. It is not less responsive or "dead".


Cool !! What kind of bike is it?

Aluminum, steel, titanium, carbon fiber: all have finite lives. Given reasonable care, all will outlast you. (And I don't even know how old you are.) :)

Doc

I don't know if this is still the case today, but about 10-12 years ago, it was the 'common wisdom' that aluminum frames were not meant for extended use, but rather to be raced a season or two and then retired, because the metal would fatigue and the frame would not be safe.

This might have simply been a bit of retro-grouch lore, or perhaps back then aluminum frame technology was less refined and frames _were_ weaker.

Looking at the godzilla tubing and giant gussets on Al frames today, i doubt this is still the case, unless you are jumping off small buildings on a daily basis. ;)

Many of the aluminum frames of yesteryear were glued together as skilled welders were in short supply. These had a short life, in general.

Doc

The only reason someone would care about a frame "going dead" is if they want to up sell you on a CF or Ti frame..

Many of the aluminum frames of yesteryear were glued together as skilled welders were in short supply. These had a short life, in general.

DocNonsense... Outside of a defective bond there were noissues. Welds can be defective too. And neither is a part of the lore of aluminum tuning to mush with age.

Cool !! What kind of bike is it?

Vitus 979 Duralinox - not welded but "glued and screwed" so it must be one of those "short life" frames :)

Here is the frameset at Nashbar!
http://www.nashbar.com/profile_moreimages.cfm?category=130&subcategory=1176&sku=13102&brand=

Vitus 979 Duralinox - not welded but "glued and screwed" so it must be one of those "short life" frames :)

Here is the frameset at Nashbar!
http://www.nashbar.com/profile_moreimages.cfm?category=130&subcategory=1176&sku=13102&brand=Yeah, you obviously got a defective one.
;)

Metal bicycle frames do not go dead. This is an old wives tale. What can happen with aluminum frames, as well as those made from other materials is a fatigue failure. Essentially, after many low amplitude stress cycles, the frame can crack under a fairly light loads. I have broken many frames this way (no aluminum ones yet though!)

Most aluminum frames are quite well designed, and will last more than long enough under normal conditions. I have an old cannondale that I have not been able to break yet, but I am trying. I wouldn't worry too much about it. There are good frames made from aluminum, just as there are good frames made of carbon, steel and ti. The design and manufacturing of the frame is more important than the material used.

I like my aluminum frame better since it has gone dead and isn't so darned harsh.

Yes it does. An AL frame can and will eventually feel less responsive or "dead" usually this happens after several years of riding. A general rule of thumb is five years though there will soon be plenty of people here to dispute this.

Heck, I think all aluminum frames feel dead. Steel is real!

[QUOTE=Gonzo Bob]Vitus 979 Duralinox - not welded but "glued and screwed" so it must be one of those "short life" frames :)



Nice bike.

I like my aluminum frame better since it has gone dead and isn't so darned harsh. :roflmao:

Here's a picture of my De Rosa. PROOF that aluminum wears out. Those tubes used to be straight. 3 years of hard riding later......well, you can see for yourselves what happened.

Here's a picture of my De Rosa. PROOF that aluminum wears out. Those tubes used to be straight. 3 years of hard riding later......well, you can see for yourselves what happened.

Must have been agrevated by the intense heat generated by supersonic air flow past your frame. Maybe you do need a Ti frame!

Well, I do live in the desert SW, so heat might've had something to do with it. That and the lower barometric pressure (5000' altitude,) but clearly - who wants an aluminum bike if they're going to end up like mine?

Here's a picture of my De Rosa. PROOF that aluminum wears out. Those tubes used to be straight. 3 years of hard riding later......well, you can see for yourselves what happened.

That bike is totally ruined. I'll take it to the dump for you. Just let me know when to pick it up. :)

In order to understand the fatigue failure mode of aluminum, one must understand an S-N curve or fatigue curve and how it's used by frame designers. An S-N curve is a plot of stress (Y-axis) that a material can withstand over a number of cycles (X-axis). This is a decay curve and for aluminum never bottoms to a plateau thus as the number of cycles increase, the strength will keep reducing until failure. Steel, OTOH will plateau to somewhere around 50% of it's UTS (ultimate tensile strength) somewhere around 10 million cycles and no amount of cycling (with loads below that curve) will cause a fatigue failure.

So how is this used? Well, because we know the strength of a material over time (actually cycles), we know how to design the part in order to keep the anticipated loads below that curve for a certain expected lifetime of the structure. Aluminum parts are generally designed so that the loads they see cause them to have an expected minmum lifespan of somewhere around 500 million cycles on the low end and as much as a couple of billion cycles (depending on the variety of aluminum and shape) on a conservative side. The average bike may not see these number of cycles for decades. In the end, "it's the design, stupid." If the design is very conservative and the shape keeps the loads well under the S-N curve then even a material such as aluminum which has no fatigue limit (keeps losing strength and never plateaus) can be used in bike frames that will result in a lifespan longer than their owners. For aluminum, many designers will design a part so that they take peak loads of 25% to 30% of UTS thus even somewhere beyond 500 million cycles, there is still enough strength in the material to support those loads. This is why so many aluminum parts are big and chunky.

The skilled welder thing is nonsense; actually the bonding technique used years ago is SUPERIOR to the welding used today! Airplanes use AL frames and NO airplane frame is welded-they are all bonded. Bonding allows for flexing to take place without breaking, welds will and do break-given enough time and stress. But even airplanes have to brought in periodically to have the frame checked. The reason bonding isn't used today is because it would: A) cost more due to extensive hand labor (welding can be done by robotics in China); and B) welding allows for more room in the area of tube shape and size. Robotics kind of leaves out the skilled welder idea now doesn't it?

Now as far as to AL fatigue issues read these:
http://www.anvilbikes.com/story.php?news_ID=11&catID=3
http://www.rivendellbicycles.com/html/101_framematerials.html

Here's a picture of my De Rosa. PROOF that aluminum wears out. Those tubes used to be straight. 3 years of hard riding later......well, you can see for yourselves what happened.

Thats an optical illusion, that frame isnt bent. It's that the wheels are actually square, and that makes the frame appear bent!!

Here's a picture of my De Rosa. PROOF that aluminum wears out. Those tubes used to be straight. 3 years of hard riding later......well, you can see for yourselves what happened.

Gee, that's just awful; hey, I'll give you $50 for it...

In order to understand the fatigue failure mode of aluminum, one must understand an S-N curve or fatigue curve and how it's used by frame designers. An S-N curve is a plot of stress (Y-axis) that a material can withstand over a number of cycles (X-axis). This is a decay curve and for aluminum never bottoms to a plateau thus as the number of cycles increase, the strength will keep reducing until failure. Steel, OTOH will plateau to somewhere around 50% of it's UTS (ultimate tensile strength) somewhere around 10 million cycles and no amount of cycling (with loads below that curve) will cause a fatigue failure.

So how is this used? Well, because we know the strength of a material over time (actually cycles), we know how to design the part in order to keep the anticipated loads below that curve for a certain expected lifetime of the structure. Aluminum parts are generally designed so that the loads they see cause them to have an expected minmum lifespan of somewhere around 500 million cycles on the low end and as much as a couple of billion cycles (depending on the variety of aluminum and shape) on a conservative side. The average bike may not see these number of cycles for decades. In the end, "it's the design, stupid." If the design is very conservative and the shape keeps the loads well under the S-N curve then even a material such as aluminum which has no fatigue limit (keeps losing strength and never plateaus) can be used in bike frames that will result in a lifespan longer than their owners. For aluminum, many designers will design a part so that they take peak loads of 25% to 30% of UTS thus even somewhere beyond 500 million cycles, there is still enough strength in the material to support those loads. This is why so many aluminum parts are big and chunky.


"Zzzzzzz..."

;)
Well, I do live in the desert SW, so heat might've had something to do with it. That and the lower barometric pressure (5000' altitude,) but clearly - who wants an aluminum bike if they're going to end up like mine?

The heat definitely has affected something, but I don't think it's your bike...

Ha! :D

I really appreciate the offers to take my deformed aluminum bike, but I just couldn't consider putting anyone at risk. I'm just too safety conscious.

I really appreciate the offers to take my deformed aluminum bike, but I just couldn't consider putting anyone at risk. I'm just too safety conscious.

good answer.. :)