RivReader asks if aluminum bars should be replaced after 5 years?

[Michael]

In a cool interview with Nitto exec Mr. Yoshikawa, Grant asks this question. Nitto exec leaves it up to consumer. So I was wondering if anything to be concerned about. Anyone know anything about aluminum bar life?
Do I need to throw away the old used set of bars I have? Don't want any accidents.

[Aaron Young]

I don't have any expertise regarding metallurgy - only my own experience riding bars that are 20+ years old.  Upon visual inspection they appear fine and I've never noticed anything strange while riding with them.  I plan to continue ring them until someone declares I'm completely nuts... which could theoretically happen at any time, right?

Aaron Young

Vancouver, WA 

On Monday, March 18, 2013, Michael wrote:

In a cool interview with Nitto exec Mr. Yoshikawa, Grant asks this question. Nitto exec leaves it up to consumer. So I was wondering if anything to be concerned about. Anyone know anything about aluminum bar life?
Do I need to throw away the old used set of bars I have? Don't want any accidents.

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[Ryan Ray]

I had a friend who broke his collarbone recently when his vintage cinelli bars snapped during a decent. I immediately thought about this.

I did think it was 10 years though, right?

- Ryan

[William]

You pose two questions:

1.  Anyone know anything about aluminum bar life?

I know a little bit about fatigue life of materials.  Any metal that is cyclicly loaded will fatigue and fail eventually.  Just about every metal has a similar look to it on an S-N curve (Wikipedia that for an explanation).  The take home is that almost everything eventually wears out and fails.  It's just a matter of when.  Steel is a notable exception.  If steel is cyclicly loaded at a low enough Stress, then it essentially never fatigues.  Incredible stuff.  Anyway, Aluminum does fatigue and fail...eventually.  When?  It depends on how much you are stressing it and how many cycles you put on it daily.  

2.  Do I need to throw away the old used set of bars I have?

Nitto is going to say what they say because they generate these S-N curves and test the heck out of their products.  They do see parts fail after lots of cycles, and what they recommend is going to be conservative.  When Nitto says 5 years, I think 20.  I do not think 50 years.  You don't know when your bars are going to fail unless you know REALLY accurately what the loading history of your bars is.  In other words, you have no idea.  Anybody who decides to buy and ride used equipment assumes some additional risk because you just don't know for sure what the history is.  If you think you would feel a lot more comfortable replacing your handlebars, then I'd say do it.  

On Monday, March 18, 2013 12:50:43 PM UTC-7, Michael wrote:

[Jim Thill - Hiawatha Cyclery]

The number of years is irrelevant. Some skinny person who rides upright and gingerly on smooth roads 5 miles per week is going to get 500 years out of the bar.

[William]

Jim

I think that's what I said.  The cycle life is determined by how it's loaded, and is captured on an S-N curve.  You are correct that a tiny load is at the ultra-long life end of the S-N curve.  If the S-N curve tells us that the cycle life is 50million cycles, and if you do 100,000 cycles per year, then Bob's your uncle, it's 500 years of life.  

For all us (relatively) normal people, we have no clue what cycle we are on.  So we are left with judgement.  Like "I weigh 170, and I don't reef on my bars too hard, so I think I'll worry after 20 years or when I notice my bars sagging, whichever comes first".  Someone else may decide "I weigh 110, and it's a path bike.  I'll never replace bars out of fear".  Finally, another person might say "I weigh 240 and sprint to every single city limit sign, and climb out of the saddle on my fixie on every hill.  5 years sounds like a good plan"

The thing that shocks me is how often I see people using bars that are visibly sagging.  The tops of the handlebars drooping downward, and the hooks no longer parallel.  That's scary.  

[Philip Williamson]

So aluminum bars sag before breaking? I only ask, because I'm a 250 lb guy using 25 year old WTB offroad drops on a fixed gear bike... offroad sometimes. 

http://www.flickr.com/photos/philipwilliamson/8547042814/

Philip

www.biketinker.com

[Jeremy Till]

Oh man, those bars are hella warped, look at how flared they are!  Must be a deathtrap.  You should send them to me immediately for proper disposal. 

[William]

I don't know if they sag before breaking, but I do know aluminum has a cycle life.  It merely scares me to see folks riding bars that are badly and symmetrically bent, clearly from tons and tons of use.  

Your offroad fixie is gorgeous, and I trust your judgement.  The tinker can smell fatigue, and that's a fact. 

On Monday, March 18, 2013 4:15:07 PM UTC-7, Philip Williamson wrote:

[Eric Platt]

Philip - very nice looking bike.  Have had one set of bars fail years ago, but they were flat bars on a mountain bike.  Will admit to thinking about this as I put a used set of 48cm Nitto Noodles on my SimpleOne this spring.  Hopefully they will last another year or two. 

 

On my drop bar bikes, will probably change them after a few years.  Might be a good reason to go for steel bars in the future. 

 

Eric Platt

St. Paul, MN

[Joe K]

Oh, man, now you've got me thinking.  I took 20-year-old Modolo aluminum bars off my old Raleigh.  I'd crashed them into a telephone pole, yet there's no *visible* damage to the bars.  And so I put them on my "new" beater when I needed a wider bar a couple of months ago -- because I'm such a cheapskate.  Guess I'd better go and yank on them a bit to see if I detect any issues...

Joe K

[Matt Beebe]

I remember reading about a year ago, either on the blug or in a broadcast email from Riv, that there were plans for steel Noodle bars.    If this is the case, amen, and I'll definitely be buying them.    Rivendell seems to have steel upright bars covered between the Boscos and the Bullmooses, but I'd be pumped to have a steel version of the Noodle bar.

[Michael]

Wouls steel bars get rusty if ridden in the rain alot?

[Peter Morgano]

My cromo Bosco bars came a bit rusty on the inside, just hit them with some framesaver. I guess they would rust on the outside if you left them in the rain a lot. If its that big a concern you could paint them yourself. Little rustoleum primer and then some topcoat, 10 bucks total. I wouldn't recommend it for a whole bike but I have done bars before and they came out pretty nice. Prep is key. Then again, I love painting stuff.  Bruce over here in NJ would do bars for 30 bucks I think if you wanted to get them done.

On Tue, Mar 19, 2013 at 12:48 PM, Michael <john1...@gmail.com> wrote:

Wouls steel bars get rusty if ridden in the rain alot?

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[M D Smith]

Ryan wrote:

I had a friend who broke his collarbone recently when his vintage cinelli bars snapped during a decent. I immediately thought about this.

To which I reply:

One thing to keep in mind is that vintage (anything pre-1998) Cinelli bars are very slightly larger (26.4mm) than most "high end" stems, which are 26.0mm.  One can sort of fit the bars into the stem, but when the clamp bolt is tightened it deforms the bars and slightly ovalizes them.  That makes all sorts of stress risers that will ultimately lead to a catastrophic snap.  I've seen broken aluminum bars a few times, and every one was crammed into an undersized stem.

-Mike in Htfd, CT

[Ron Mc]

great photo Philip.  

I put 30 years on a GB Maes bend.  

Jim, as far as the "cycle and S-N curve" goes, only cycles that are 70% or greater of the permanent bending load count.  Everything below that is within the endurance limit.  

[Ron Mc]

p.s. - misusing science in marketing is known by marketers as "the snow job"

[Jim Thill - Hiawatha Cyclery]

It was William who introduced the concept of S-N curves, not Jim. I don't think he misused science in his explanation. That said, it's somewhat simplistic to reduce the complicated fatigue life of bicycles to relationships discovered in controlled lab settings.

In the real world, bike parts do break, even if they're made of steel. This is observed reality at least once a week at my job. If you dig into the science of why things break, you can certainly learn a lot of terminology and study endless log-scale graphs. You can get a PhD in the subject, which I tried once. Even the smartest guy or gal in the room can only begin to guess what sorts of stresses a handlebar will endure (or has endured), what scenarios will lead to eventual failure, or how long that will take. As somebody pointed out, even a good bar can fail prematurely if clamped improperly in the stem. What of faulty heat treating or surface defects or undetectable debts and dings that become stress risers? I've only just scratched the surface of muddying the waters of science and its predictions...

Nitto makes their best guess, erring on the side of safety, and says 5 years of use. Obviously many bars last much longer, and a few don't even make it to 5 years. Personally, I'm not concerned about this arbitrary number. If you are concerned, I say buy a new bar. It's worth $100 or whatever for peace of mind.

[grant]

I thought-think-was taught that steel has a load limit below which it can withstand a theoretically infinite number of cycles (flexes), but that aluminum has no such thing.
Permanent bending load limit is the Yield strength. Yield strength is the force required to bend a material to the point where it doesn't snap back all straight again. Spring steel (used in springs) has a high yield strength; paperclip steel (used in ________) is the opposite.

On this topic, vaguely: I was at a materials testing facility two days ago, and remember the hooplah I set off when I suggested that maybe modulus varies with UTS (sorry for the jargon, but I'm too tired to explain). I got so much "correction" mail that I was forced into a slightly insincere recantation. Well...the head guy at this place was saying that a crank arm made of X would be stiffer than one of idental design made of Y, and so I said politely, "Oh really?" and he said of course, and I said what about modulus's independence of UTS? and he said no way, we've done this test a zillion times, and then showed me a tech insider's website that listed diff moduli for two alum alloys of diff strengths.

I'm just here to cause trouble. I won't respond to an discussions on this, on account of I've beenthere done that...and I will always play my "two year diploma, what kind of fool listens to me?" card, if pressed.

[William]

"as far as the "cycle and S-N curve" goes, only cycles that are 70% or greater of the permanent bending load count.  Everything below that is within the endurance limit."

Steel has an endurance limit.  Moderately stressed steel, cycled below the endurance limit, lasts forever (if you'll pardon the term).  That's why I said steel is such incredible stuff.  It really is incredible.  

We were talking about aluminum.  Aluminum has no endurance limit.  The lower the cycling stress, the longer it lasts, but there is no lower limit below which the stress cycles "don't count".  I'm not trying to snow anybody and I am not an employee of the Nitto marketing department.  

[Ron Mc]

Sorry Grant, William, Jim - I stand corrected - aluminum has no endurance limit.  

Monolithic is the term.  

On Monday, March 18, 2013 2:50:43 PM UTC-5, Michael wrote:

[PATRICK MOORE]

I have an idea! Let's talk about carbon fiber bars! Seriously, what about them?

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[Leslie]

I find all of this interesting, but am coming at it from a different direction;  as a geologist, I (used to) look at a lot of structural deformation on rock (instead of steel), looking at elastic deformation versus plastic deformation, stress versus strain, Mohr's circles, Young's modulus, etc. etc..;  looking at rock, it's different than steel, but, at the same time, it's applying the same concepts...

Carry on, I'm enjoying this from the sidelines....

[William]

Leslie

Was Popov your undergrad text on mechanics of materials?  

[Joe Bernard]

I'm starting to understand the thinking behind all that thick, heavy steel on 3-speed Raleighs...

 

Joe "Um, carbon bar? No thanks" Bernard

Vallejo, CA.

[Leslie]

On Wednesday, March 20, 2013 3:04:11 PM UTC-4, William wrote:

Leslie

Was Popov your undergrad text on mechanics of materials? 

No;   being in geology, I had Dana's for Mineralogy (well, Klein/Hurlbut after Dana's), Blatt for Petrology, Davis for Structural, then later Hatcher for Structural further... also a lot from Telford in Applied Geophysics, too;   but I didn't have 'material' science (as far as metals testing, etc., as the engineering side would have...)    BS in stright-laced field geology, MS is in engineering geology, but dealt more with slope stability, engineering properties of geologic materials (ASTM testing, soils, etc.), hydrogeology, etc.....

If I was over on the engineering side of campus, probably would have;  but not on my side....

[Jim Thill - Hiawatha Cyclery]

I also went to school for geology. I took "mineral physics" in grad school, which was basically stress/strain/fatigue on the molecular level. I've never used it in any professional capacity, but when it comes to discussing handlebar failures, I can sling BS with the best of them.

[ted]

... trouble, with a capital T and that rhymes with P and that ...
As is frequently the case in the physical sciences, if you measure accurately enough commonly stated generalities turn out not to be exactly correct. Published values for the stiffness of different types of steel are different. Same thing for aluminum.

But those differences are not that big, and the people developing the materials are usually focused on other properties that vary more dramatically. Apply something like the logic Grant uses to argue a few ounces of frame weight are meaningless, and you are likely to conclude that the differences in the stiffness of various steels used to make bikes (or aluminums used to make components) is insignificant.

Now fatigue life of components, that makes bulk modulus and yield strength of a material seem trivially simple by comparison.

[Joe Bernard]

Guy goes into a bar: "Maybe modulus varies with UTS, amirite, people!?"

On Wednesday, March 20, 2013 8:39:45 AM UTC-7, grant wrote:

[Eric Platt]

Agree with Jim T. that he can be an expert when he wants to be.  Just have to teach him to include "It's a little known fact..." at the beginning.

 

All this talk has made me decide my next bike build is going to have steel handlebars.  Might even have to build up a bike around them.

 

Stay tuned<g>.

 

Eric Platt

St. Paul, MN

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[Jim Thill - Hiawatha Cyclery]

Looking forward to see what you come up with Eric! You can use one of our work stands on Friday if ya want.

[Scott Henry]

Interesting, my undergrad was in geology too.   Surprising to see others on the list with similar backgrounds.  Like Jim, I never actually used mine too much.  Taught middle school science for a few years though.  Past that it just makes me feel smart when seeing some cool outcrops on an offroad ride.

For the record, I use my bars till they show some problems or I get bored with them.  I'd doubt I have any older than 15 years max, generally they get used, swapped, traded, sold...

Cheers,

Scott

On Wed, Mar 20, 2013 at 10:20 PM, Jim Thill - Hiawatha Cyclery <thil...@gmail.com> wrote:

I also went to school for geology. I took "mineral physics" in grad school, which was basically stress/strain/fatigue on the molecular level. I've never used it in any professional capacity, but when it comes to discussing handlebar failures, I can sling BS with the best of them.

[Eric Platt]

Jim,
May take you up on the offer. Might be pretty cold in the garage tomorrow morning.  That is, if I don't do the build tonight.

Eric Platt
St. Paul, MN

On Mar 21, 2013 7:26 AM, "Jim Thill - Hiawatha Cyclery" <thil...@gmail.com> wrote:

Looking forward to see what you come up with Eric! You can use one of our work stands on Friday if ya want.

[Steven Frederick]

Yeah, I'm re-thinking an old (original?) set of dirtdrop bars I picked up at a swap meet last year.  They're a bit ragged looking anyway and I don't know how much or how roughly they were used...

[Cyclofiend Jim]

Lots of salient points in this thread - particularly about finite cycles to failure of aluminum. 

I'll only add a couple thoughts that I keep in my head: 
- Aluminum bends well - once. Maybe twice. 
- Consider where your teeth sit in relation to your handlebar and stem.
- There is no price for piece of mind. 

A few years ago, when I decided to stop my quickbeam by placing my index finger between the handlebar and a suddenly-opened car door, my Nitto bar actually didn't bend all that much. 

http://www.flickr.com/photos/cyclofiend/3675517009/in/photostream/

I actually had to force myself to cut it so I would not reuse it down the road.   But, I do expect my rigs to ramble over a variety of terrain, and there is cyclical load involved.  I use a bright light and magnifying lens every few months when I clean things.   But, I've had worse luck with cranksets than I ever have had with bars.  Which is where I think I'd like to see some steel.

http://ramblings.cyclofiend.com/?p=399

http://www.flickr.com/photos/cyclofiend/2089364757/

http://www.flickr.com/photos/cyclofiend/3950425015/

- Jim / cyclofiend.com

[Cyclofiend Jim]

On Thursday, March 21, 2013 3:20:19 PM UTC-7, samh wrote:

So you weren't seriously injured when you broke your cranks?

No.  I actually (generally) fall pretty well.  Hit the ground on the old Campy one (was climbing, out of saddle when it happened, and luckily was not run over).

http://ramblings.cyclofiend.com/?p=226

On the newer one, it was on the Hilsen, and I would argue that the reason I didn't hit the ground had a lot to do with the inherent stability of GP's designs.

http://www.flickr.com/photos/cyclofiend/sets/72157622446951852/

- J

[William]

That's where Adam and Jamie (mythbusters) would say "Now, there's your problem!"