# Buying Used - Things to Consider



## Zeet (Mar 24, 2013)

Buying used can be a very shrewd move on the part of a cyclist. Many dollars can be salvaged when buying a used bicycle. However, there are several pitfalls present within the world of used bicycles. The first of which is bicycle frame material. Most cyclists venturing into the used bicycle market would fare best by looking for a chromoly steel bicycle. That's especially so, when the used bicycle was manufactured more than ten years ago. Aluminum bicycles that have been in regular use for ten years or more, should not be considered as viable candidates for purchase, due to fatigue issues regarding stress. Generally speaking, the older the aluminum frame, the less it should be seriously considered for purchase. Aluminum bicycles do not lose value at the same rate as steel framed bicycles. Aluminum bicycles that have been used extensively, usually show signs of that use via scratches, dents, gouges, etc.. One should become leery of any freshly painted aluminum bicycle more than ten years old. Chromoly steel bicycles do not suffer the same fatigue issues experienced by aluminum frame bicycles. A well-maintained forty-year-old steel framed bicycle will perform just as well, as it did the first day it was rolled off the showroom floor of your LBS. Nobody can really say that about an aluminum framed bicycle.


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## Zeet (Mar 24, 2013)

*The Bicycle Savvy and Rust*



Zeet said:


> Buying used can be a very shrewd move on the part of a cyclist. Many dollars can be salvaged when buying a used bicycle. However, there are several pitfalls present within the world of used bicycles. The first of which is bicycle frame material. Most cyclists venturing into the used bicycle market would fare best by looking for a chromoly steel bicycle. That's especially so, when the used bicycle was manufactured more than ten years ago. Aluminum bicycles that have been in regular use for ten years or more, should not be considered as viable candidates for purchase, due to fatigue issues regarding stress. Generally speaking, the older the aluminum frame, the less it should be seriously considered for purchase. Aluminum bicycles do not lose value at the same rate as steel framed bicycles. Aluminum bicycles that have been used extensively, usually show signs of that use via scratches, dents, gouges, etc.. One should become leery of any freshly painted aluminum bicycle more than ten years old. Chromoly steel bicycles do not suffer the same fatigue issues experienced by aluminum frame bicycles. A well-maintained forty-year-old steel framed bicycle will perform just as well, as it did the first day it was rolled off the showroom floor of your LBS.


Also, when buying used, one should be somewhat knowledgeable about both bicycle mechanics and structure. If a cyclist is looking to buy a used bicycle, he should be able to identify signs of existing mechanical problems. He should also be able to determine frame and fork irregularities. Additionally, being able to differentiate surface rust from critical oxidation is of the utmost importance, as well. If a prospective used buyer is not bicycle savvy, then it would serve him best to seek out the expertise of an expert, to assist him in the purchase of a used bicycle.


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## Zeet (Mar 24, 2013)

*Used Carbon Fiber*



Zeet said:


> Also, when buying used, one should be somewhat knowledgeable about both bicycle mechanics and structure. If a cyclist is looking to buy a used bicycle, he should be able to identify signs of existing mechanical problems. He should also be able to determine frame and fork irregularities. Additionally, being able to differentiate surface rust from critical oxidation is of the utmost importance, as well. If a prospective used buyer is not bicycle savvy, then it would serve him best to seek out the expertise of another, to assist him in the purchase of a used bicycle.


* Used carbon fiber framed bicycles should never be purchased from complete strangers, as carbon fiber is notorious for its ability to conceal structural damage. Many cyclists who have previously crashed their expensive CF road bikes, will think nothing of passing their liabilities onto the unsuspecting prospective buyers awaiting them on either Craigslist or eBay. Buying a used CF bike is considered as risky business when purchasing from anyone. That's especially so when purchasing from people outside of our usual social circles. It's extremely dangerous to cycle upon a previously crashed CF framed bicycle! Therefore, IMO, it would be advisable to avoid used CF bikes, altogether.


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## Zeet (Mar 24, 2013)

*Avoid Used Online Purchases*

It should be considered as completely inadvisable to purchase any used bike from eBay. Always keep your search for a used bicycle local. Keep your search local, so that you can better inspect and test ride the bike. Never purchase any bike without at first, test riding it. At least with Craigslist, you can always physically inspect and test ride the bike. OTOH, with eBay, that's not so easily done, unless the seller lives nearby.


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## Data_God (Oct 9, 2012)

Serious Question: Joined in March 2013 and you have almost 1300 posts. Do you actually ride a bike ? Or simply spend all day on this particular forum posting and replying to your own posts ?

Bill


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## armstrong (Jul 9, 2013)

I've read here on a previous occasion to always buy steel/cromo if considering a used bike, and to always avoid aluminium. There was no qualification to that statement. Your posts are the first to qualify that this is particularly important if the bike is more than 10 years old, which implies its not that important if the bike is less old than that. What if the bike we're considering is like from 2010, and was purchased and basically never used? Is it OK to go aluminium in that case? Cause it seems all mid-range bikes these days (between $500 and $1000) are aluminium, so there's really no avoiding it if that's where we're looking for a used bike.


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## seacoaster (May 9, 2010)

OP – do you have any data to support your statement that aluminum bikes more than 10 years old should be avoided?

Commercial aircraft are kept in service for decades, and they are made from aluminum.


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## armstrong (Jul 9, 2013)

If I'm not mistaken, airplane parts are replaced regularly, and after a period of time, the entire plane is basically made of new parts once the old ones have been replaced. FWIW, they learned this the hard way. I believe it was in the 1950s that they introduced AL as a material for planes. They were lightweight and thus seemingly effective, but due to metal fatigue, a lot of the early planes fell out of the sky. That's when they realized AL wasn't all they thought it was.


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## tlg (May 11, 2011)

seacoaster said:


> OP – do you have any data to support your statement that aluminum bikes more than 10 years old should be avoided?
> 
> Commercial aircraft are kept in service for decades, and they are made from aluminum.


Naaa, just more of the same biased "frame material" opinions that make up many of his posts.



armstrong said:


> If I'm not mistaken, airplane parts are replaced regularly, and after a period of time, the entire plane is basically made of new parts once the old ones have been replaced.


Not quite accurate. Sure they replace parts as needed. But things like the fuselage aren't replaced.

What determines an airplaneâ€™s lifespan? | Need to Know | Air & Space Magazine
An aircraft's lifespan is measured not in years but in pressurization cycles. Each time an aircraft is pressurized during flight, its fuselage and wings are stressed. Both are made of large, plate-like parts connected with fasteners and rivets, and over time, cracks develop around the fastener holes due to metal fatigue.

"Aircraft lifespan is established by the manufacturer," explains the Federal Aviation Administration's John Petrakis, "and is usually based on takeoff and landing cycles. The fuselage is most susceptible to fatigue, but the wings are too, especially on short hauls where an aircraft goes through pressurization cycles every day." Aircraft used on longer flights experience fewer pressurization cycles, and can last more than 20 years. "There are 747s out there that are 25 or 30 years old," says Petrakis.

Aircraft Structural Design
Primary structure for present transport aircraft is designed, based on average expected operational conditions and average fatigue test results, for 120,000 hrs. For the best current methods of design, a scatter factor of 2 is typically used, so that the expected crack-free structural life is 60,000 hrs​
60,000hrs = 8hrs per day x 365days per yr x 20yrs.
But somehow Zeet arbitratily puts a 10yr life on aluminum bikes.


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## Zeet (Mar 24, 2013)

Data_God said:


> Serious Question: Joined in March 2013 and you have almost 1300 posts. Do you actually ride a bike ? Or simply spend all day on this particular forum posting and replying to your own posts ?
> 
> Bill


The large number of posts is primarily due to my inability to downshift on this website. I therefore can't create paragraphs. Therefore, I simply post upon previous posts. Might look cumbersome, but it would look worse, IMO, if I simply ran all of my ideas together.


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## JCavilia (Sep 12, 2005)

armstrong said:


> If I'm not mistaken, airplane parts are replaced regularly, and after a period of time, the entire plane is basically made of new parts once the old ones have been replaced. FWIW, they learned this the hard way. I believe it was in the 1950s that they introduced AL as a material for planes. They were lightweight and thus seemingly effective, but due to metal fatigue, a lot of the early planes fell out of the sky. That's when they realized AL wasn't all they thought it was.


That's pretty much all wrong. Aluminum was used for the metal parts of airplanes from very early on (one of the Wright Brothers' innovations was an engine that was mostly aluminum. The earliest planes were mainly made of wood and fabric, and frames later used tubular steel, but when they started making the skins of metal, it was usually aluminum.

The skins of modern airplanes are made of aluminum, including the pressurized fuselage vessel that undergoes a fatigue cycle with every flight. The skins are not replaced on any schedule. 20-year-old airliners with thousands of cycles are still flying every day. Rarely do parts fail from metal fatigue, and major parts are not replaced often. It is certainly not true that they replace the whole plane bit by bit eventually.


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## Zeet (Mar 24, 2013)

armstrong said:


> I've read here on a previous occasion to always buy steel/cromo if considering a used bike, and to always avoid aluminium. There was no qualification to that statement. Your posts are the first to qualify that this is particularly important if the bike is more than 10 years old, which implies its not that important if the bike is less old than that. What if the bike we're considering is like from 2010, and was purchased and basically never used? Is it OK to go aluminium in that case? Cause it seems all mid-range bikes these days (between $500 and $1000) are aluminium, so there's really no avoiding it if that's where we're looking for a used bike.


I have no objection to buying used aluminum, as long as it has not been subjected to extensive use, due to aluminum's issue with fatigue. The fact that steel possesses a fatigue limit, below which an infinite number of stress cycles can be endured, is directly related to my preference. Aluminum doesn't have such a fatigue limit. With aluminum, every stress cycle is counted and will eventually lead to its most inevitable failure. I use ten as a somewhat arbitrary number of years, based upon Motobecane's warranty: http://motobecane.com/warranty/html


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## Zeet (Mar 24, 2013)

seacoaster said:


> OP – do you have any data to support your statement that aluminum bikes more than 10 years old should be avoided?
> 
> Commercial aircraft are kept in service for decades, and they are made from aluminum.


Motobecane USA | Warranty


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## Zeet (Mar 24, 2013)

seacoaster said:


> OP – do you have any data to support your statement that aluminum bikes more than 10 years old should be avoided?
> 
> Commercial aircraft are kept in service for decades, and they are made from aluminum.


www.kineticdiecasting.com/aircraft.html


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## tlg (May 11, 2011)

Zeet said:


> I have no objection to buying used aluminum, as long as it has not been subjected to extensive use, due to aluminum's issue with fatigue and the fact that steel possesses a fatigue limit, below which an infinite number of stress cycles can be endured.


BUT.... steel does suffer from fatigue. 
What if a steel frame was designed with a 35ksi stress limit and an alum frame was designed with a 25ksi stress limit? The alum frame will last much longer.












> I use ten as the arbitrary number of years, based upon Motobecane's warranty: https://motobecane.com/warranty/html


BUT.. BUT... Motobecane only warrants steel frames for 20yrs. When will you start telling people not to buy steel frames made before 1993??


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## Zeet (Mar 24, 2013)

tlg said:


> BUT.... steel does suffer from fatigue.
> What if a steel frame was designed with a 35ksi stress limit and an alum frame was designed with a 25ksi stress limit? The alum frame will last much longer.
> 
> 
> ...


 That's the point! Steel does possess such an fatigue limit as an intrinsic property, whereas aluminum doesn't. Notice the continuous curve for aluminum. That's just its nature! Each stress cycle counts against its lifespan... OTOH, with steel, we can plainly see where the fatigue limit exists. Therefore, with normal use, steel can endure an unlimited number of cycles. As long as normal use is maintained below its fatigue limit. Since the only nemesis of steel is oxidation, if kept dry, there should be no intelligent reason to limit steel's lifespan at all!


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## seacoaster (May 9, 2010)

Zeet said:


> Motobecane USA | Warranty


I think it would be helpful if you could provide bicycle frame failure data to support your statement. Warranty period has absolutely nothing to do with useful service life.


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## mpre53 (Oct 25, 2011)

JCavilia said:


> That's pretty much all wrong. Aluminum was used for the metal parts of airplanes from very early on (one of the Wright Brothers' innovations was an engine that was mostly aluminum. The earliest planes were mainly made of wood and fabric, and frames later used tubular steel, but when they started making the skins of metal, it was usually aluminum.
> 
> The skins of modern airplanes are made of aluminum, including the pressurized fuselage vessel that undergoes a fatigue cycle with every flight. The skins are not replaced on any schedule. 20-year-old airliners with thousands of cycles are still flying every day. Rarely do parts fail from metal fatigue, and major parts are not replaced often. It is certainly not true that they replace the whole plane bit by bit eventually.


Exactly. The problems arose with one particular aircraft, the DeHaviland Comet, which was the first jet placed into passenger service. The failures (I believe 3 Comets suffered catastrophic failures) were primarily due to the size of the cabin windows, and the lack of adequate reinforcement there. Once DeHaviland became aware of the problem, they reinforced the fuselage around the windows, and down sized the windows. There were no further problems involving Comets.


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## armstrong (Jul 9, 2013)

Is a 1950 plane considered a "modern" airplane?

Anyways - I'm not calling myself an expert, but I watched a documentary some years ago and they said that they went to all-aluminium fuselages in the 1950s and had some unexpected catastrophic failures. It might have been that the fuselage was designed as "one piece" at the time (I think this was the "new" feature of the planes at the time), and that the weakness of the aluminium over repeated use led to the in-flight failures, so they changed the design and/or materials (I don't recall). Anyways - I recall the show mention the weakness of aluminium, and they obviously don't have the same catastrophic failures occurring now, so something has changed, but the weakness of aluminium over repeated use had some culpability.

In any case - regarding aluminium and metal fatigue, can someone answer the guy's query? Given what has been posted about airplanes, can you explain why bicycles will weaken over time, but planes do not, given they are both made of aluminium?


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## tlg (May 11, 2011)

Zeet said:


> That's the point! Steel does possess such an fatigue limit as an intrinsic property, whereas aluminum doesn't. Notice the continuous curve for aluminum. That's just its nature! All stress cycles count against its life span... OTOH, with steel, we can plainly see where the fatigue limit exists. Therefore, with normal use, steel can endure an unlimited number of cycles. As long as normal use is maintained below its fatigue limit. Since the only nemesis of steel is oxidation, if kept dry, there should be no intelligent reason to limit steel's lifespan at all!


How do you know your steel frame was designed around 30ksi minimun stress levels? FACT is you don't. 
Your assumption only holds true if the frame was designed properly. Which you simply don't know. You can't just look at that chart and assume all bikes are made the same. 

The REAL point is proper design is more important than blindly looking at material.

BTW.... Motobecane only warrants steel frames for 20yrs. When will you start telling people not to buy steel frames made before 1993??


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## tlg (May 11, 2011)

armstrong said:


> In any case - regarding aluminium and metal fatigue, can someone answer the guy's query? Given what has been posted about airplanes, can you explain why bicycles will weaken over time, but planes do not, given they are both made of aluminium?


Aluminum doesn't weaken with time. It weakens with cyclic loads. 
The comparisson with alum planes is they safely operate many hours per day, every day, for decades (60,000hrs use). Nobody is operating bicycles anywhere near that. Blindly picking "10yrs" out of ones arse is quite foolish.

Maybe if you operate your aluminum bike 16hrs every day for 10yrs you should be concerned.


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## armstrong (Jul 9, 2013)

tlg said:


>


What do the lines represent? Do they represent failure?


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## armstrong (Jul 9, 2013)

So what's the verdict? Avoid aluminium or not? And is there any reason to avoid aluminium in an unridden bike regardless of its age? There's always folks who buy decent bikes and basically don't ride them at all, only to sell them years later at a pretty good discount. Is it OK to shop for those?


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## JCavilia (Sep 12, 2005)

armstrong said:


> In any case - regarding aluminium and metal fatigue, can someone answer the guy's query? Given what has been posted about airplanes, can you explain why bicycles will weaken over time, but planes do not, given they are both made of aluminium?


Nobody said they don't weaken; they just weaken slowly enough to last as long as they need to, which is quite a long time.

I don't have any data on how often aluminum bike frames fail from fatigue. I'd like to see it. What people are disagreeing with here is Zeet's fallacious reasoning. He starts from premise (1) that aluminum is subject to fatique losses and will eventually fail; and premise (2) that steel, if the stresses are below a certain level, will not fatigue. And then. without quantifying anything, he jumps to the conclusion that a used aluminum frame is more likely to be unsafe than a used steel one. The theoretical possiblity of the aluminum failure may be irrelevant if the time involved is 30 years of normal use. And the condition of the steel bike is very much affected by treatment and especially storage. A steel bke frame with a ton of invsible rust inside the tubes may not be a better buy than an older aluminum frame. 

And the 1950's experience with the DeHaviland Comet (probably the subject of the documentary you saw) doesn't say much of anything about bike frames. It jus demonstrates that designing a new machine has hazards and they don't always get everything right the first time. The response to that problem was not to stop using aluminum (there's no real alternative material that's strong enough, light enough and cheap enough); it was to fix the design. Tens of thousands of ariliners have made tens of millions of flights since then. They all have aluminum fuselages and wings (until the carbon-fiber 787).


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## tlg (May 11, 2011)

.....


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## Zeet (Mar 24, 2013)

tlg said:


> Aluminum doesn't weaken with time. It weakens with cyclic loads.
> The comparisson with alum planes is they safely operate many hours per day, every day, for decades (60,000hrs use). Nobody is operating bicycles anywhere near that. Blindly picking "10yrs" out of ones arse is quite foolish.
> 
> Maybe if you operate your aluminum bike 16hrs every day for 10yrs you should be concerned.


Yes. In fact, aluminum does "weaken" after cyclic applied loads. The aluminum specimen will maintain its relative strength throughout its lifespan, just prior to its final stress cycle. After that point, it will suffer material failure from stress. Aluminum becomes seriously "weakened" the closer it gets to its point of failure. The actual average fail date of related aluminum bicycle frames can only be disputed due to insufficient data (we desperately need a larger database for the fate of all frame materials) . However, the fact that an aluminum fail point exists, is absolutely indisputable! Steel does not possess such a point where failure can be predicted or estimated.


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## JCavilia (Sep 12, 2005)

armstrong said:


> So what's the verdict? Avoid aluminium or not? And is there any reason to avoid aluminium in an unridden bike regardless of its age? There's always folks who buy decent bikes and basically don't ride them at all, only to sell them years later at a pretty good discount. Is it OK to shop for those?


Yes, it's okay. Look for signs of abuse, obviously, as you would with any product. If the bike's been crashed and dinged, take that into account.

Certainly, an "unridden" bike raises no such concerns. Even Zeet's cautious approach doesn't suggest that the aluminum goes weak from sitting in the garage (corrosion issues aside, but those are a concern with steel, too, and usually a bigger one).


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## Zeet (Mar 24, 2013)

JCavilia said:


> Nobody said they don't weaken; they just weaken slowly enough to last as long as they need to, which is quite a long time.
> 
> I don't have any data on how often aluminum bike frames fail from fatigue. I'd like to see it. What people are disagreeing with here is Zeet's fallacious reasoning. He starts from premise (1) that aluminum is subject to fatique losses and will eventually fail; and premise (2) that steel, if the stresses are below a certain level, will not fatigue. And then. without quantifying anything, he jumps to the conclusion that a used aluminum frame is more likely to be unsafe than a used steel one. The theoretical possiblity of the aluminum failure may be irrelevant if the time involved is 30 years of normal use. And the condition of the steel bike is very much affected by treatment and especially storage. A steel bke frame with a ton of invsible rust inside the tubes may not be a better buy than an older aluminum frame.
> 
> And the 1950's experience with the DeHaviland Comet (probably the subject of the documentary you saw) doesn't say much of anything about bike frames. It jus demonstrates that designing a new machine has hazards and they don't always get everything right the first time. The response to that problem was not to stop using aluminum (there's no real alternative material that's strong enough, light enough and cheap enough); it was to fix the design. Tens of thousands of ariliners have made tens of millions of flights since then. They all have aluminum fuselages and wings (until the carbon-fiber 787).


 J, we do indeed need a larger database, from which we should be able to confirm the bicycle material frame failure rate. However, without that data, all we're left with is the theory. Now should we attempt to apply it, or not?


armstrong said:


> What do the lines represent? Do they represent failure?


Yes. Failure is exactly what that particular graph represents! With aluminum the failure rate is continuous. However, with steel, a limit exists. Below which, it can endure an unlimited number of stress cycles and not fail at all.


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## JCavilia (Sep 12, 2005)

Zeet said:


> J, we do indeed need a larger database, from which we should be able to confirm the bicycle material frame failure rate. However, without that data, all we're left with is the theory. Now should we attempt to apply it, or not?


When the theory amounts to the assertion that "aluminum when subjected to repeated stresses wil eventually fail (but I don't know how long that is or how it relates to the typical usage life of a bicycle)", what is there exactly to "apply."

Do you even have anecdotal evidence of aluminum bike frames spontaneously falling apart after the kind of usage history you're talking about? A story or two? Anything?


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## Zeet (Mar 24, 2013)

JCavilia said:


> When the theory amounts to the assertion that "aluminum when subjected to repeated stresses wil eventually fail (but I don't know how long that is or how it relates to the typical usage life of a bicycle)", what is there exactly to "apply."
> 
> Do you even have anecdotal evidence of aluminum bike frames spontaneously falling apart after the kind of usage history you're talking about? A story or two? Anything?


I have entirely too much anecdotal evidence. Not only did I get to work an entire summer at a friend's bicycle dealership, I also belonged to two different road bike clubs and one touring club. I've actually personally witnessed aluminum bottom brackets and seat tubes that cracked from stress. I have yet to witness a steel bicycle frame crack from stress. OTOH, I have witnessed more than my share of steel frames break, due to rust. However, the topic here, is stress.


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## Zeet (Mar 24, 2013)

armstrong said:


> So what's the verdict? Avoid aluminium or not? And is there any reason to avoid aluminium in an unridden bike regardless of its age? There's always folks who buy decent bikes and basically don't ride them at all, only to sell them years later at a pretty good discount. Is it OK to shop for those?


The verdict is just what I stated earlier. Avoid all potentially extensively used aluminum framed bicycles. If an aluminum bicycle is ten years old or older, I don't personally feel that it would be wise to pursue it as a used bicycle, given the theory about the inherent fatigue issues of aluminum. Therefore, if you have a choice between an old aluminum framed bicycle and an old steel framed bicycle, there should be no question as to which bicycle should be preferred. IMO, that would be like being offered a choice between spam and filet mignon.


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## tlg (May 11, 2011)

Zeet said:


> I've actually personally witnessed aluminum bottom brackets and seat tubes that cracked from stress.


Ok, how many cyclic loads at what stress levels? 

How on earth do you possilby know that these were cyclic failures as opposed to exceeding the design stress? 
Answer: You haven't a clue.



> I have yet to witness a steel bicycle frame crack from stress. OTOH, I have witnessed more than my share of steel frames break, due to rust. However, the topic here, is stress.


Since you claim to be able to diagnose stress failures, answer me this... what caused this bottom bracket failure? Cyclic failure or excessive stress failure? (FYI, that's titanium)


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## Zeet (Mar 24, 2013)

tlg said:


> Ok, how many cyclic loads at what stress levels?
> 
> How on earth do you possilby know that these were cyclic failures as opposed to exceeding the design stress?
> Answer: You haven't a clue.


 * 3, 507,467, 322,187 *...So there! I did know the answer! 


> Since you claim to be able to diagnose stress failures, answer me this... what caused this bottom bracket failure? Cyclic failure or excessive stress failure? (FYI, that's titanium)


Cyclic failure is the same thing as failure from excessive cyclical stress...


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## tlg (May 11, 2011)

Zeet said:


> Cyclic failure is the same thing as failure from excessive stress!


So you're saying that titanium BB (which has a fatigue limit) suffered a cyclic failure. ut:


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## Zeet (Mar 24, 2013)

tlg said:


> So you're saying that titanium BB (which has a fatigue limit) suffered a cyclic failure. ut:


No. I am not stating that at all! However, I am stating the all stresses are cyclical by nature. Stress can only manifest itself cyclically. That's whether it's excessive, or not. I respect you, TLG...


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## tlg (May 11, 2011)

Zeet said:


> No. I am not stating that at all! However, I am stating the all stresses are cyclical by nature. An excessive amount stress can only manifest itself cyclically. I respect you, TLG...


Quit beating around the bush and explain why that BB failed if titanium has a fatigue limit. Clearly it should've lasted over 40yrs according to you. Even more since titanium doesn't rust.

You purport to be an expert on this stuff, shying people away from aluminum since it doesn't have a fatigue limit. So enlighten us.


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## Zeet (Mar 24, 2013)

tlg said:


> Quit beating around the bush and explain why that BB failed if titanium has a fatigue limit. Clearly it should've lasted over 40yrs according to you. Even more since titanium doesn't rust.


 From your photo, it would appear that your Ti example had weld issues. Something not too uncommon for problem Ti frames.



> You purport to be an expert on this stuff, shying people away from aluminum since it doesn't have a fatigue limit. So enlighten us.


I've never claimed to be an expert! ....From what crap pot did you get that idiocy? Also, my goal is not to make people shy away from aluminum bicycles in general, just those old used aluminum bicycles that are unfamiliar to them.


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## ExChefinMA (May 9, 2012)

Zeet, 

Since you seem to be the expert here, can you tell me if it’s worth rebuilding my 1983 lugged steel Fuji road bike? It’s lived most of its life at the beach, but was kept indoors and mostly suffers from neglect.

But before you answer that question, can you tell me where your structural engineering degree is from? I’d like to ensure that your credentials are sufficient to answer my question.

EEC


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## Zeet (Mar 24, 2013)

ExChefinMA said:


> Zeet,
> 
> Since you seem to be the expert here, can you tell me if it’s worth rebuilding my 1983 lugged steel Fuji road bike? It’s lived most of its life at the beach, but was kept indoors and mostly suffers from neglect.
> 
> ...


LOL!....My advice would be for you to trash your current bike and take up another sport, altogether. It's called, Cliff-Jumping!


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## ExChefinMA (May 9, 2012)

Zeet said:


> LOL!....My advice would be for you to trash your current bike and take up another sport, altogether. It's called Cliff-Jumping!


Zeet, 

Is this your way of saying that you have no legitimate credentials? I am shocked, you seem to profess a lot of "facts", are you telling me that this is all just speculation on your behalf? No empirical data to support it?

Wow, all of this "expert" advice you are providing to the unknowing masses.

Good thing on the other hand, everyone is allowed to have their own opinion, no matter how wrong it is. 

EEC


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## Zeet (Mar 24, 2013)

It's public knowledge and fairly well-known amongst most, that aluminum has fatigue issues. Most experienced cyclists of whom I'm aware, would never attempt to deliberately seek out an old aluminum bicycle frame for personal use. That's especially so, when there are other frame choices available.

Frame Materials


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## Zeet (Mar 24, 2013)

Zeet said:


> Frame Materials


www.brightspoke.com/c/understanding/bike-frame-materials.html


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## ExChefinMA (May 9, 2012)

Zeet said:


> Frame Materials


Zeet, 

You are basing your professional opinion on the website of a bike manufacturer? Interesting. Thank you for sharing that link, based on that, I still would question the validity of the data. It would be like a chef at a 5 star restaurant basing his menu on what McDonald’s nutrition sheets say about their food. 

It’s anecdotal at best, subjective at worst, and maybe just a manufacturers desire not to work with a material because of price point. But, what do I know, I’m just an ExChef.

EEC


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## tlg (May 11, 2011)

ExChefinMA said:


> Zeet,
> 
> You are basing your professional opinion on the website of a bike manufacturer?


What are you talking about? Boeing gets all their data from that website before they build airplanes from aluminum. And then they tell airlines not to buy used 10yro airplanes unfamiliar to them.


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## Zeet (Mar 24, 2013)

ExChefinMA said:


> Zeet,
> 
> You are basing your professional opinion on the website of a bike manufacturer? Interesting. Thank you for sharing that link, based on that, I still would question the validity of the data. It would be like a chef at a 5 star restaurant basing his menu on what McDonald’s nutrition sheets say about their food.
> 
> ...





tlg said:


> What are you talking about? Boeing gets all their data from that website before they build airplanes from aluminum. And then they tell airlines not to buy used 10yro airplanes unfamiliar to them.


Fatigue limit - Wikipedia, the free encyclopedia


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## Zeet (Mar 24, 2013)

ExChefinMA said:


> Zeet,
> 
> You are basing your professional opinion on the website of a bike manufacturer? Interesting. Thank you for sharing that link, based on that, I still would question the validity of the data. It would be like a chef at a 5 star restaurant basing his menu on what McDonald’s nutrition sheets say about their food.
> 
> ...





Zeet said:


> Fatigue limit - Wikipedia, the free encyclopedia


Wikipedia is generally considered as an objective and unbiased information source. Wouldn't you agree?


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## GOTA (Aug 27, 2012)

If it's on the internet it must be true


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## JoePAz (Jul 20, 2012)

Zeet said:


> ... I have yet to witness a steel bicycle frame crack from stress. OTOH, I have witnessed more than my share of steel frames break, due to rust. However, the topic here, is stress.


My friend busted his CrMo GT mtn bike many years ago. His bike was maybe 3-4 years old at the time and never saw any jumps. Plus his is only about 150-160lbs so no heavy weight. We ride in Arizona so it is very dry so no rust at all. GT gave him a Ti frame as a replacement. He still rides that as well as an aluminium FS bike. 

Steel will crack and fail just like any material. Most of these failures are not from normal fatigue, but from defects that weakened the material. Any frame can have a material defect in it and you crack a Ti-frame with hidden weld defect.


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## tlg (May 11, 2011)

Zeet said:


> Fatigue limit - Wikipedia, the free encyclopedia


Nothing there, or any of your sources, about 10yrs. YOU are using your expert knowledge to make that 10yr leap.


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## JoePAz (Jul 20, 2012)

Zeet said:


> * 3, 507,467, 322,187 *...So there! I did know the answer!
> 
> Cyclic failure is the same thing as failure from excessive stress...


No it is not. Fatigue failure is not the same a stress overload failures. Overload mostly comes from crash damage and is one time load application. Fatigue is from low stress, but many cycles. From structural position these are very different types of failures. As for the failed Ti frame I have not idea what type of failure it was, but probably fatigue fracture where stresses were elevated from weld defect. Over time this defect grows until it reaches a critical size and then fails quickly.


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## ExChefinMA (May 9, 2012)

tlg said:


> Nothing there, or any of your sources, about 10yrs. YOU are using your expert knowledge to make that 10yr leap.


Now, tlg, you know that zeet is only trying to protect us. He knows better, he uses google and has studied this for years. Heck, I bet he's even read the New England journal of medicine and can diagnose any of your pains and ailments. Not to mention he's going to be the defense attorney for the latest sports figure up on charges. 

:eye roll:

EEC


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## Zeet (Mar 24, 2013)

JoePAz said:


> No it is not. Fatigue failure is not the same a stress overload failures. Overload mostly comes from crash damage and is one time load application. Fatigue is from low stress, but many cycles. From structural position these are very different types of failures. As for the failed Ti frame I have not idea what type of failure it was, but probably fatigue fracture where stresses were elevated from weld defect. Over time this defect grows until it reaches a critical size and then fails quickly.





tlg said:


> Nothing there, or any of your sources, about 10yrs. YOU are using your expert knowledge to make that 10yr leap.





JCavilia said:


> When the theory amounts to the assertion that "aluminum when subjected to repeated stresses wil eventually fail (but I don't know how long that is or how it relates to the typical usage life of a bicycle)", what is there exactly to "apply."
> 
> Do you even have anecdotal evidence of aluminum bike frames spontaneously falling apart after the kind of usage history you're talking about? A story or two? Anything?


Here's the true nature of fatigue with respect to stress cycles, as it's related to aluminum: www.bobbrowncycles.com/eng.htm#section3


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## ExChefinMA (May 9, 2012)

Zeet said:


> Here's the true nature of fatigue with respect to stress cycles, as it's related to aluminum: www.bobbrowncycles.com/eng.htm#section3


Zeet, 

Do you have any sources that aren't frame makers or Wikipedia? Not that I would EVER think you would use biased data to try to make a valid point. 

EEC


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## Data_God (Oct 9, 2012)

Zeet said:


> The large number of posts is primarily due to my inability to downshift on this website. I therefore can't create paragraphs. Therefore, I simply post upon previous posts. Might look cumbersome, but it would look worse, IMO, if I simply ran all of my ideas together.


Better sometimes to be silent and thought a fool than to open your mouth and remove all doubt.


Bill


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## AndrwSwitch (May 28, 2009)

Since we're trying to bring in anecdotes, here are some things I've broken.
-a couple of rims, due to overload (crashing)
-a rim due to fatigue (cracks around spoke holes/a stupid Bontrager design)
-spokes due to fatigue
-spokes due to overload (no crash, but plowed a laden bicycle into a railroad tie; do the math)
-a mixed-material bike frame, in a steel section, near a weld, from fatigue
-a handlebar, from fatigue
-a handlebar, from overload
-a bottle cage, probably fatigue
-a bike rack, probably fatigue

You'll notice there's a bunch of steel in the list.

I find the frame I broke the most amusing. It was a Raleigh Technium road frame. I figured if it ever broke, it would be at one of the bonds. But the 20-year-old glue did fine and the steel failed.

Given how subjective safety factors can be when it comes to calculating allowable loads for parts subject to cyclic loading... I think it's all about the engineering. Material's just not that important next to the massive difference in service life these calculations can make.

I sometimes wonder if people know how to read logarithmic scales when they fire off these threads. If the service life of an aluminum part in continuous use is 1000 years...


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## robdamanii (Feb 13, 2006)

I, for one, can't believe people are still taking this troll's bait.

He's as bad as (if not worse than) the spammers, and he's probably a shill for BikesDirect.


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## Zeet (Mar 24, 2013)

robdamanii said:


> I, for one, can't believe people are still taking this troll's bait.
> 
> He's as bad as (if not worse than) the spammers, and he's probably a shill for BikesDirect.


If you'd research my bicycle recommendations, you'd plainly see that if I'm a shill for Bikesdirect, then I must also be a shill for Performance, Nashbar, Trek, Jamis, Raleigh, GT, Scott, Schwinn, Cannondale, Specialized, Giant, and Surly, as well!


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## Zeet (Mar 24, 2013)

Data_God said:


> Better sometimes to be silent and thought a fool than to open your mouth and remove all doubt.
> 
> 
> Bill


And just what would I have to gain or lose by either quoting previous post to repost, or just simply telling the truth about it. Perhaps, it might have been better, just to ignore the fact that I can no longer downshift on this website. Crazy as it may sound, it's true!


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## Dave Cutter (Sep 26, 2012)

You know..... IMHO the “*things to consider when buying* [a] *used*” bicycle might have less to do with frame material than just a decent bicycle knowledge base.

Experienced cyclists can look over a used bicycle... and maybe with the addition of test ride... determine if the bicycle is the correct size ( a VERY important factor) and what adjustments, parts and repairs might be needed. And... maybe most importantly... what the bicycle will be when fixed, restored, updated... or whatever the plan is for the bicycle in question. 

If I am recapturing a memory with a copper tone 1964 Schwinn Varsity... it will be 41 pounds of gas-pipe like, heavy steel. I loved the Schwinn I rode back in 1964. But.... it isn't what I want to ride tomorrow. And no amount of upgrades are going to make it special... except in the history and memory that it represents.

I am not saying new cyclist shouldn't buy used bicycles. But in many cases the purchase could be more of a learning experience... than than a cycling experience.

With money as a separate issue.... bicycle choice becomes an emotional issue. Nothing more... nothing less. If a cyclist has his/her heart set on the latest greatest cool painted carbon fiber feather weighted go-faster.... nothing less will do. 

Others may see the new go-fasters as nothing more than unlimited factory runs of the same bicycles. Sold with different badges and decals... depending on the store it is sold at. A handmade custom.... or rare classic old vintage bike may seem like a better choice.

Many people don't see the emotional choice as different from a logical choice. And with little difference in the logic of the selection... it's impossible to hammer out a “better” choice. It's like arguing about who is tougher... Rambo or Rocky. 

I think many newbies with little used bicycle knowledge might end-up buying a too large, very heavy, 10 speed, with worn parts, and friction shifters.... (and... for twice what should be the proper price). Then instead of adding to our ranks another cyclist.... we collectively have one more bicycle hanging in a garage.


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## Zeet (Mar 24, 2013)

JoePAz said:


> No it is not. Fatigue failure is not the same a stress overload failures. Overload mostly comes from crash damage and is one time load application. Fatigue is from low stress, but many cycles. From structural position these are very different types of failures. As for the failed Ti frame I have not idea what type of failure it was, but probably fatigue fracture where stresses were elevated from weld defect. Over time this defect grows until it reaches a critical size and then fails quickly.


True. However, I wasn't aware that we were discussing "overload".


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