Sunday, April 15, 2012

Warnings of Failure

Cantabrigian Mechanics
Among cyclists I know, many ride steel bikes and a good number have experienced frame failure of some sort. Really, I hear stories about it all the time. One woman described pedaling through town when suddenly her bicycle felt wobbly and loose. Turned out the seat tube had cracked, just above the bottom bracket. Another had a similar experience with his first bike: The downtube detached right at the bottom bracket joint and he had a bad fall. I have also heard multiple accounts of snapped chainstays. 

Anecdotes like this make me think about frame failure in relation to frame material. We know that steel bends, whereas carbon fiber snaps. Steel fails gradually, whereas carbon fiber fails suddenly and catastrophically. And this is why we consider steel a safer material for frame construction. But what I am wondering is: How does this difference translate into real world experience? 

What gets me about the stories of steel frame failure, is that the cyclists never see it coming. From their point of view, these too are sudden failures. In reality, I do not doubt that the failures were in fact gradual - but save for checking for evidence of stress with a loupe before every ride, how does the cyclist benefit from that gradualness? 

Based on my limited experience test riding roadbikes, I am not attracted to carbon fiber frames. I prefer the ride quality of steel and titanium. But I am not sure I share the safety concerns about (quality) carbon fiber frames that some voice. Sure, in theory the frame can fail suddenly and catastrophically. But in practice, how would this differ from the gradual failure of steel that to the cyclist feels equally sudden?

73 comments:

  1. It depends on the care that the cyclist takes in examining the steel versus the carbon frame. As noted in my "carbon" series, the failure of a carbon frame is essentially an overload after some impact or other triggering event. A steel frame, if loaded under the "endurance limit," will last longer than the cyclist, and even the cyclist's grandchildren. My oldest steel frame is over 40 years old, with untold thousands of miles. Its weakest point is where the seat post is clamped.

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  2. I, too, have seen frame failures on steel frames. Granted, many steel bicycles are loaded to the hilt (tourers) and therefore are placing a lot more stress on their respective points. Steel dents, too.

    But composite is (potentially) going to be the strongest material available. Perhaps if builders of carbon frames began putting on triple water bottle holders and rack mounts they might begin to appeal to the touring squad.

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  3. Even as someone who vastly prefers steel bikes over other materials, I think the hoopla over carbon's "sudden failure" mode is overblown.

    That being said, and based largely on the significant number of "I scored the laminate on my carbon bike and now it may be compromised" posts and messages on various forums, I'd still be leery of riding a carbon bike that I had to pay for, especially considering my usual riding venues that vary from pavement to dirt, with the occasional fall.

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    1. Carbon's failure mode IS typically "sudden." Unlike steel, which is notch sensitive in fatigue, but notch insensitive statically, carbon is also sensitive to notches statically. That doesn't mean it isn't a good material; just that it will fail statically due to damage - suddenly, without warning, and catastrophically. No hoopla required.

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  4. My little experience here. I have witnessed two riders fail on carbon bikes, one a frame crack and one a fork crack. They both were taken off the road in ambulances. The failures were immediate, especially the fork failure.

    I can't say I have witnessed a steel fork or frame react like that before to failure. I have had two steel frame failures myself and when they happened I could still ride the bike home. One was a crack right above the bottom bracket on the seat tube and one was a bent seat stay.

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  5. New flash: everything breaks.

    "Steel fails gradually" is an urban myth applied too broadly across too many conditions.

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    1. Exactly... True Temper s3 doesn't fail gradually. I've heard stories about 853, too.

      But, let's be honest: if you're concerned about sudden, catastrophic frame failure, steel is still the best bet. Yeah, there's exceptions, but all these years of steel frames, there's still no bustedsteel.com yet.

      http://www.bustedcarbon.com/

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  6. "We know that steel bends, whereas carbon fiber snaps."

    This is too simplified. Steel has usually lower yield strength (YS) compared to its ultimate tensile strength (UTS), while in case of the carbon fiber both of these values are pretty close. This means that plastic deformation (flow) of carbon fiber is minimal before it reaches its UTS. This is why you will likely not see carbon fiber frame being deformed. It just snaps right away.

    See more here: http://en.wikipedia.org/wiki/Ultimate_tensile_strength

    Regarding the failure of bike frames, the main question is whether it was the tubing that cracked or was it the weld. Bike frames are made of high UTS steel with very thin walls. In order to have more safety margin before they break, we would have to allow for much more of plastic deformation (lower YS, higher UTS). This would likely mean increasing wall thickness making the frame heavier (If I remember correctly from my college classes).

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  7. It has been my experience that steel telegraphs its failure. I have never seen a steel bike "snap".
    Lots of people don't think to inspect their bikes very often for visual clues of wear or problems.
    (I am often among them, but trying to be better about it.)
    Think of how many folks you know who check their cars' tire pressure, look under the body for small leaks, and so forth before getting in and starting up. We get complacent.

    Also, how many of these failed frames are several decades old, with potentially many owners and lots of riding stresses put on them through their service lives?

    The only reason I feel okay traveling downhill at 40+ mph on a 34-year-old road bike is that I know a very careful scientist has inspected the raw frame himself...

    This is not to say a spontaneous failure in a steel frame can't happen, just that it's rare in my experience.

    As for carbon- I tend to be diffident about it because the truly nice rides are much more expensive than I feel I can afford, and their service life is an unknown quantity.

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  8. Too many years ago when I was a paperboy the forks of my Raleigh racer (model unknown - it was red and yellow 5spd?) snapped instantaneously across both legs, 3inches below the crown, with no impact that I can remember. There was no indication of any sort, I just suddenly eat tarmac!

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  9. Steel frames fail because of road vibration resonance that slowly tears a steel frame apart where the vibration is stopped, i.e. the bottom bracket. Thicker walled steel tubing will stop some of this breakage by being better able to sustain/absorb the road vibrations

    http://www.brighthub.com/engineering/mechanical/articles/111822.aspx

    "The nature of resonant vibration and the accompanying amplification of fatigue stress are discussed in relationship to the damping energy absorbed by a vibrating system. The resonance amplification factor is defined as a measure of the severity of a resonant condition. The sources of damping in a
    vibrating system are discussed and classified according to whether they are external (structural) or internal (material). Data on the internal damping properties of a variety of structural materials are presented and the generalizedbehavior is discussed. In cases where internal damping is significant, the
    importance of both fatigue strength and damping properties of materials as joint criteria for resonant strength is demonstrated and quantitatively expressed. The analyses are made in terms of the resonant strength constant for the material (the material factor) and the volume-stress function of the part (the part factor).

    http://www.dtic.mil/dtic/tr/fulltext/u2/039439.pdf

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  10. This is a very interesting question but can you expand on your observation, "I prefer the ride quality of steel and titanium". What is it that you don't like in terms of ride on carbon frames?

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    1. At the risk of resorting to a cliche, the ride feels "dead" and hollow to me and I find that disconcerting. If I were some pro racer and the carbon would give me that last bit of advantage yadda yadda yadda, then sure I would ride it. But as a regular person it just doesn't seem worth it to ride a bike that doesn't feel enjoyable.

      As far as ride harshness goes, there is some variety and even within my small sample not all carbon bikes felt the same. So I am not talking about vibration dampening qualities when I say I do not like the ride. It's something else that bothers me regardless of how soft/harsh they ride. Maybe it's the stiffness.

      Interestingly, I am okay with the feel of a carbon fork on a steel or Ti frame, but not with a carbon frame.

      What I'd like to try is one of those bikes with carbon tubes and then either aluminum or titanium lugs and see how that feels.

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  11. I've cracked two. Each time there was an extended period - weeks - where I tried to track down the cause of the persistent creaking sound. Many parts of the bike were disassembled, greased, waxed, siliconed, tightened. Having been through it once did not make me any more astute the second time. It does make me somewhat skeptical of most stories of sudden failure.

    If you ride in the city, surrounded by noise, you won't hear the creak. If it's a windy day you won't hear the creak. If your bike makes noise for many reasons you won't hear the creak.

    I also remember watching a downtube pull clean out of a BB shell. I'd sold the bike a few days before and I was right behind the broken frame at 30-35mph in a criterium turn. Leaning much deeper than the boys do these days. Potholes. The frame had been held together by nothing but a brazing pin and paint. Well known respected builder. The rider did not crash. He rode it out with aplomb.

    The owner who finds the crack early is the one who cleans his bike frequently and meticulously. You already know if you will do that or not. The other very helpful diagnostic tool is a shopstand. Elevating the bike to eye level and having decent lighting shows faults immediately that would be hidden a long time if looking down at the bike or kneeling while trying to get this or that done. The only other way I know to find them earlier is to paint all your bikes yellow, it shows cracks better.

    Just a couple weeks back I did a descent on a cracked rim at 61mph. Sixty year old rider on a fifty year old bike but I am not quite goofy enough to use a fifty year old rim. New, heavy duty top end top dollar rim from a mfr with impeccable reputation. There were indications there was a problem but they were easy to ignore. It was not easy to find the crack even when the wheel was in the stand a few days later. It happens. We all rely on luck. A lot.

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    1. I suspect a lot of old steel frames last so long because they were heavier built. A four year old quality lightweight steel frame cracked on me recently - I too had been trying to find the source of the clicking noise. (The shop/manufacturer replaced with no quibble.) But none of the knackered old (steel ) biikes I have ridden before ever cracked, nor had I even heard of it happening.

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    2. Sounds just like any other click your bike might make.

      Bikes get used hard. They can be designed to stand up to normal use or designed to withstand predictable abuse. The first approach makes a high performance bike with a short lifespan. The second approach is open ended and most of us would choose a light bike that is less than eternal. Lugs work well to absorb predictable abuse.

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  12. I suspect failure modes for steel and carbon frames are very similar. Failure modes for components seems to be very different. I've seen a number of pedals snap carbon cranks, with hospital visit results, but never the same with steel or alu cranks. Similar for handlebars and seat posts. I've seen a few frame failures on steel, alu and carbon frames and they've all been pretty similar in terms of impact. For frame failures the bike typically gets a bit difficult to control but manageable. For fork failures, pretty horrific regardless of material.

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  13. "whereas carbon fiber snaps"

    "carbon fiber fails suddenly and catastrophically"

    these myths are spread by "steel is real" grouches who know next to nothing about composites. modern cf tubing and framing is made of ridiculously strong multidirectional weaves aand a properly maintained carbon fiber bike will outlast any metal bike. i have seen dozens of riders continue riding damaged carbon fiber for months to years. i should emphasize that this is unsafe and unnecessary since carbon fiber is the easiest frame material to repair.

    i have broken quite a few steel and aluminum frames via every day riding. i have never had this happen to a carbon fiber frame.

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    1. To be fair, those who know lots about composites do not seem to disagree.

      I am not talking here about which is more durable. I have faith in the durability of high quality current production carbon fiber. I am talking about the way in which the two materials break when they do.

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    2. You are right in general of course. But to say "modern cf tubing and framing is made of ridiculously strong multidirectional weaves" isn't completely accurate. CF isn't stronger or weaker than steel, it has a higher strength to weight ratio. And with constant pressure to reduce component weights as low as possible, designs are often done using the minimal material that can provide adequate strength. That is a recipe for failure with any material.

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    3. "modern cf tubing and framing is made of ridiculously strong multidirectional weaves".....

      I'm with MaxUtility on this one. Velonews published last year an example of someone running over a squirrel in a paceline and both legs of their cf fork sheered off--FROM RUNNING OVER A SQUIRREL. Honestly, that doesn't happen even with lightweight high-performance steel--I once ran over a medium sized dog that ran out into the middle of a paceline in a race while riding a Colago Super--a steel bike. The bike (and the dog) survived. The dog was a lot bigger than a squirrel.

      Carbon fiber bikes in the 14-15 lb. range tend to have catastrophic failures. Heavier cf bikes are no doubt more robust.

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    4. I own a 2012 spec roubaix and do some pretty harsh riding in some pretty harsh conditions and I am a 240lb. 6'6 clydesdale. I feel confident hopping up and down curbs on my commute, deal with heavy road bumps and have litterally slammed bone jarring pot holes (narrow road shoulders in heavy traffic makes them unavoidable sometimes). My avg commute speed is about 15 to 18 depending on the way the wind blows so im not super fast but certainly keep a pace. I have owned and punished steel/cromo mountain bikes and a slew of aluminum. Without question aluminum is the most likely to fail. I have had many alumium components fail fast and hard with no warning (especially in the cold). I have also splintered bottom bracket shafts twisting them in two and Ive broken about 3 down tubes on aluminum bikes. Carbon seems to me the most resilient hands down. I used to work in a bike shop in memphis where we had a trek guy demo the strength of thir oclv (back 15 years ago) and when striking a cromo tube, the cromo tube dented pretty bad, the carbon tube nothing. Simply stated, carbon is the best most resilient and capable material bikes frames can be made from (personal feel aside). The catastrophic failure (no doubt hyped) is likely due to poor design. Specialized uses big long sweeping welds (main reason i choose it over the very exciting looking kestral) that build incredible strength into the shape, also note the lack of straight bars... Design is the key to a reliable carbon build but the same is true with all materials. Personally my Spec Roubaix has proven itself to be trusted under heavy harsh and repeated (over)load. I for one think carbon is awesome and I must say I love my spec roubaix... best bike ive ever owned hands down.

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    5. I had an accident with a Carbon Frame Bike. I hit a car that turned right in front of me -- I was cruising at around 15-20 mph. The front tire and handlebars hit the car -- including my face -- but the tire, my face, and handlebars were not damaged believe it or not. However, the entire headset completely sheered off, snapping my bike in two pieces! The impact was hard, but the headset is supposed to be one of the strongest parts of a bike -- and that totally blew apart and snapped. I am grateful for the accident, because had I been biking 30 mph downhill on a trail I regularly travel with the headset exploding in this manner, I would not be writing this comment now -- because I would have either broken my neck and be paralyzed or dead. I will never buy another Carbon Fiber Frame Bike. I was amazed to see just how thin the frame actually was at the headset. This was a bike manufactured by one of the best bike manufacturers in the U.S. In contrast, I have crashed on my steel frame Trek 520 on more than one occasion and I have never had any problems with fatigue or cracking or denting of that frame -- that bike may not be as fast as the Carbon Fiber Frame Road Bike that bit the dust -- but it is a lot safer. I will replace my deceased Carbon Fiber Bike with either an aluminum or titanium frame bike.

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  14. "I prefer the ride quality of steel and titanium"

    Ride feel has as much to do with design and engineering as frame material.

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    1. Is it possible for a traditional, track geometry style, fixed steel frame bike to “feel” and respond like a “Sportive” style carbon road bike, with 10 speed (Shimano) gears.

      I would like (at least) two bikes, one for every day 20 mile commuting/local rides and one for longer weekend endurance rides and events, up to 100 miles. Towards this end, I purchased a very nice Schindelhauer Siegfried (2010 model) urban bike and flipped it to fixed. This is a aluminum frame and I’ve had it for 8 months but it has never felt quite right and I find myself using the road bike most of the time.

      Both bikes are good quality and design and I try not to directly compare the two but I would like to know if an alternative material to carbon will ever feel like, well carbon. I like the concept of a traditional steel fixed bike but not if it will not feel and respond like the CF road bike does.

      The CF road bike is a 2007 Specialized S-Works Roubaix and has been the best bike I have owned to date. The Siegfried needs to be pushed and although quite light never “floats” or flows. With the Roubaix I can spin almost effortlessly and feel no pedal drive resistance at all but with the Siegfried, the pedals and drive must always be “maintained”. I appreciate this is a factor of fixed and some say the attraction, the sense of being connected and in touch with your bike.

      So, have I answered my own question and I just happen to prefer to be in the CF derailleur camp? or can a steel fixie really feel the same?

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  15. Two very different experiences with steel failure. First, riding downhill in my lovingly re-created SA AWX2 late '60s Schwinn Varsity and feeling an odd bobbing sensation in the front end. Stopped to look. Found crack slowly growing across a fork leg. Replaced it with a fork made for a 28" wheel Indian roadster (Kenya, circa 1972).

    Circa 1999: ex and I riding newly acquired, NOS Orbit tandem (531C, from Britain). Slammed on the front brake to avoid an errant child and the steerer snapped just above the crown race -- too much heat? I went over the bar, ex went over me. Only damage was severe bruising on my thighs thanks to bar entanglement.

    There you go. Steel and fail catastrophically too, tho' I expect that it will give warning if there is no defect in brazing or material. Can you say the same of carbon fiber? Not taking sides, just wondering.

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    1. "Orbit tandem (531C, from Britain). Slammed on the front brake to avoid an errant child and the steerer snapped just above the crown race -- too much heat"

      Oh wow. I would never have expected that. Could the fork have been defective?

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    2. That's a half-common failure. Especially for a tandem. Safest is a handmade two plate. You can see the steerer and how it's put together.
      Insisting on 2 plate exclusively would be extremism on singles - for tandems it's just good practice

      Tandem steerers should be large enough and thick enough that overheating is not a likely problem.

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    3. Interesting and a little frightening. Do you mean a double plated fork crown or something different entirely? I know next to nothing about tandems, though some time in the future we'd like a road tandem.

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    4. Yes double plated. Tandems have all sorts of failure modes singles don't. Like ripping off the head tube. If it can happen to a single it does happen to a tandem regularly.

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    5. The Orbit was absolutely the wrong tandem for neophytes being extremely light and whippy -- that tail wagged our dog so that our maiden ride was a series of broad "S's." That said, I expect that the steerer was defective in some way since (thank God) we were not going faster than 15-18 mph and the braking, while sudden, was not like running into a wall. (Speaking of which, I rode my Riv custom fixed gear into a curb one evening on the commute home, riding without adequate light -- stupid in itself. The fork bent back several degrees but the frame was unharmed and I rode the bike the remaining seven miles or so home -- was that high or low trail? Got the fork replaced, of course.

      I'd love to have a sub-20 lb carbon fiber 29er ss with 500 gram carbon fiber fork, but the breakage stories make me pause. Does anyone know anything about the durability of off road carbon frames and forks? No c-f bars or components for me, but a light (not stupid light) frameset is appealing.

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    6. One thing you just can't do on a tandem is brake while the front wheel is turned. This happens most often at walking speed and that is plenty to fold a wheel or snap a fork or both. Standing and leaning on the pedal at startup also requires that the wheel be kept straight.

      If you swerved a bit while braking that may have been enough. And too much for any fork. If the alternative was hitting a child and the "choices" were attempting a not recommended manoeuvre or intentionally dropping the bike then it's just tandems and how they are.

      All of us run closer to the edge whenever we ride than we think. Tandems are automatically edgy. As many commenters have said you can go decades without a problem. Doesn't mean you were riding with a big safety reserve.

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  16. "We know...."? "We consider...."

    Who's this "we"? Folks who keep Grant's photo on their bedside tables? The sandals/ canvas/ hemp twine club?

    I'm active in a regional racing club which has over 150 members. To give an idea of the scale, over a hundred people show up for Saturday training rides, which are run in three different categories. Probably 99% of those riders are on carbon forks, and well over 50% are on carbon frames. Over the course of a racing season, team members are involved in more than 600 person-days of racing. I've been involved with that club for seven years. Over the course of that period, I have heard of catastrophic carbon failure exactly one time, see below.

    Although I have not personally experienced one, I'm not questioning whether carbon failures can happen. I believe that the vast majority of those failures can be prevented through good assembly and maintenance habits, and by throwing away parts that have been in crashes. The only carbon-related fatality of which I am directly aware was the result of a rider insisting on continuing to ride a frame/fork which had been in a major collision with an automobile. His dealer had told him to please bring the frame in to the shop for destruction.

    Carbon has its place, and it can be a very effective and useful material. As regards ride quality -- in my experience, cheap carbon builds into a dead frame, while very-high-modulus carbon can, in the right hands, be built into a frame which is magically silky, and velvety, and which disappears under you as you accellerate or climb.

    I ride various ti and steel (with carbon forks), and a Riv, too, and I like all of them, but I can remember what those high-end carbon frames felt like, utterly intoxicating, and then sometimes late at night I can feel the bad jones building, and I have to go to my 12-step group, and get my dark urges back under control.

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    1. Who's this "we"? Folks who keep Grant's photo on their bedside tables?

      Busted! Well, not me. But Cycling Peppy keeps a framed photo next to her basket.

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    2. Peppy (the framed photos, I has thems)April 15, 2012 at 7:44 PM

      Litterbox. Get it straight.

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  17. Heh.

    Next discussion: helmets, must be worn at all times, discuss.

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    1. Thankfully, I don't think most people interpreted the post this way, and it was not meant as such. Obviously the two materials are different and break differently.

      What I meant was more from the cyclist's point of view. Is there a difference in their *experience* of one type of breakage vs the other type, and if so what is that difference. I think jp below makes a good point.

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  18. the 'suddenness' of the failure is subjective. like your story showed that people with steel felt like something was wobbly or not quite right. carbon fibre won't 'feel wrong'...it will just fail and at times put you on the ground.

    i will say i have owned many many steel bikes. most of them were on the pacific coast in what is considered corrosive conditions. none of them have failed and 2 are 20 years old now. one of them i just had repainted and it shows no signs of rusting (other than a tiny bit of surface rust). i really think how you maintain your bike (or anything for that matter) determines how long it will last and if it will fail.

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  19. "your story showed that people with steel felt like something was wobbly or not quite right. carbon fibre won't 'feel wrong'...it will just fail and at times put you on the ground."

    That was one thing I had been wondering about. So when people talk about "gradual" vs "sudden" failures, are they talking about the multi-second delay before the breakage - during which supposedly the cyclist has time to stop the bike and check what's wrong, or at least slow down? Or am I misreading?

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    1. It has been my experience that carbon failures happen suddenly, meaning happening in a few seconds, vs. steel which seems to give some warning, enough to "come to a stop and check it out."

      I don't ride steel for the damage control though or failure rates ect; I ride it for the ride, the looks, and the longevity. If I could get those qualities in carbon I would ride carbon, but sadly, all the carbon bikes seem ugly to me. I'm not convinced of the longevity either, but you never know, I guess a few more years (like 20) are in order to make that determination. Totally IMHO.

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  20. Look, this "gradual" thing came up because Grant wrote it. It didn't exist before.

    As Rob alluded to, different steels break in different ways.

    Personally I've broken a steel frame, an alu crank, multiple cro-mo axles, cracked alu rims, steel pedals, steel bars, alu stem, alu bars and a bunch of other stuff I can't remember. Oh yeah, I broke a state-of-the-art Ti frame too. Some had their breaks "telegraphed", others were sudden. There is no pattern. You jump, land, something breaks, you're on the ground.

    The focus on frame material failing is silly - of much more relevance is checking one's bike over before each ride and not leaving it in the elements in a harsh climate for years.

    I've seen so many people crash due to their own negligence in maintenance it renders the question of materials obsolete.

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    1. "this "gradual" thing came up because Grant wrote it. It didn't exist before."

      I have heard people completely unrelated to GP talk about the gradual failure of steel vs the sudden failure of CF. They have metallurgical arguments to back this notion up. Which I don't pretend to understand. But point is, it seems to be an idea independently arrived at. Basically those who do not like CF tend to have this opinion.

      "I've seen so many people crash due to their own negligence in maintenance it renders the question of materials obsolete."

      Oh yes, that is a topic unto itself.

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    2. Grant, imo, popularized the concept. Materials science existed way before he was born; he chose to push the way steel breaks as a way to market his own products. Nobody talked about it in the context of bikes but a handful of engineers who rode bikes, about 10 of them. Of course steel can be malleable but it can also be brittle. Depends on its chemical makeup, purity, density, wall thickness, gauge, etc. Stuff I've said before. Sites like bustedcarbon sprung up to scare people off the material/make the case for steel.

      Also mentioned above, just as with steel not all carbon is created equal. Monocoque vs. hand-layered, fiber orientation, Lance-era vs. now. Stress analysis then vs. now. Look at the down tube of a Trek Domane and look at a USPS bike. No comparison.

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    3. Carbon can be made to be pretty darn malleable, at least if my fishing rod is any indication.

      It's true, there has been a great deal of progress made in carbon fiber technology in the past decade as well, it's strong stuff and generally reliable. There are plenty of reasons one may not choose to ride a carbon bike, but the fear of spontaneous failure shouldn't be one of them.

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    4. "There are plenty of reasons one may not choose to ride a carbon bike, but the fear of spontaneous failure shouldn't be one of them."

      My sentiment exactly. I would not own a carbon fiber bike, but I sure as hell would not be afraid to ride one.

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  21. Most of the catastrophic failures I've seen in my time as a shop mechanic have been on components rather than frames or forks. Handlebars, rims, stems, seatposts and crankarms (which happened to me recently on a commute) have all snapped through.

    Most of the time, these parts have been aluminum, and, while a close inspection (possibly an x-ray) might have shown a hairline crack or stress line, even a fairly well-versed cyclist or mechanic would have been hard-pressed to spot anything, they effectively failed without warning. Sometimes people got hurt.

    The thing is, almost all steel frames, ti frames and carbon frames have aluminum parts on them.

    Interestingly, one of the most horrifically destroyed bikes I've ever seen came in this past month. The fellow was riding along when a police car hit him. Every single part of the aluminum framehad damage and the frame had snapped clean though at four points. The only major part of the bike to survive apparently intact? The carbon fork.

    But these are accidents and rarities (well, I break stuff more than most) and most people I know ride for decades without a major crash.

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  22. Seat tube breaking at or near the bottom bracket? This is suggestive of poor frame building to me. Been riding steel bikes since I was a child and now passed my half century. Never had a frame fail other than in a race when I crashed it. How many Alex Singers,Rene Herse,Jack Taylors frames have you direct evidence of failing? Frame builders fall into a range from very good, through to mediocre and then to best avoided. Orbit Cycles had a problem with quality control, and some of their work was not at the top of their game. I know this problem to have afflicted several well known frame builders for a time before being corrected. Quality control problems can arise at any stage of the manufacturing process.
    I can however relate an incident which happened on a local Sunday club ride recently where one of the tyros invested in some Zipp carbon wheels. Back wheel failed on the first ride, brought it's owner down and three other cyclists - one beside and two behind down. Very serious injuries to all four riders, lots of broken plastic in the road. Now I understand there was no warning this was about to happen.
    I do not know of a similar instance of a steel frame failing and wrecking four bikes and putting four riders in hospital. I also don't know of an instance of a traditional spoked wheel failing catastrophically without any kind of warning. (I did get my steel frame repaired that I crashed and raced it again).
    The choice of frame/component material is subjective. People have strong opinions about their choices. What I will say is, my bike has covered tens of thousands of miles, bottom bracket is square taper, lasts for about three years, chain does a lot more than 1700 miles before it needs replacing (never had one break for years). For me it is not about style and image, or buying into the marketing image of the bicycle being a not very durable consumer product. I expect value for my money and that components I put on my bike give some reasonable degree of service before they have to be replaced.

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    1. i don't know why you are discussing wheels on this thread. that is another topic and one that deals with aluminum alloys versus cf.

      i have never seen a carbon fiber frame fail catastrophically but i have seen both steel and aluminum fail suddenly (usually at the down tube weld).

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  23. I have had two steel frames fail. The first was at the site of a dent, and I did not notice until I inspected it one day. The seat tube was cracked, but not all the way around. That frame is awaiting repair. The second frame cracked all the way around the seat tube at the BB joint. I have no doubt that inferior/inexperienced framebuilding is to blame. I had no indication of failure except the frame felt "soft" and slow with no snap. While cleaning it one day I discovered the crack. Retired that one. I have little experience with carbon, besides witnessing a fork, a seatpost and a handlebar snap in two at cross races! All of those failures were instant/catastrophic, fortunately with no injuries!

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  24. One thing about steel bicycle construction is that it is a mature, well-tried technology. It's been around for, what, over 125 years? Yes, there were early aluminum bikes and other materials. But they were made in small numbers compared to steel. Maybe one commenter is right that carbon fibre will last as long as steel. But we will have to wait decades, a century to find out.
    It also depends how a bike is used. I ride several bikes, the newest twenty years old, the oldest 47. My son is a competitive slope-style dirt jumper and has had two aluminum frames and countless forks fail. But he is the (very brave) test pilot for his sponsor's products.

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  25. In the olden days, steel frames were thick-walled and heavy. These frames absolutely failed at times; we often see the ultra-heavy, legendarily sturdy "electro-forged" schwinn frames with an obvious (and unsightly) repair at where the seatstay was brazed to the seat-tube. The rest of the frame is rarely seriously damaged by anything other than rust, but the junctures could be a weak spot; not everyone was brazing with the same level of expertise, I reckon.

    In more recent years, the market has demanded lighter weight frames, and we're trying to make steel frames into something they are not supposed to be. Ultra lightweight frames made from s3 and 853 Pro Team are steel in name only, as I see it. These scarcely feel like the steel frames I'm used to, and are prone to seemingly instantaneous failure. I'm not trying to disparage any particular tubeset; to be drawn into extremely thin-walled tubing demands that the steel have a very high UTS rating, so the tubesets that I seem to be "picking on" are probably made from the best stuff available. The problem is, as i see it, there just isn't enough of that good stuff being used on these thin-walled tubes...

    I'm a 4130 chromoly type of guy. These frames can fail as well, but I've yet to be riding one while it has. I've seen nominally 4130 frames fail, usually at the chainstays (but typically bikes are described by the tubes that make up the front triangle; the stays are often composed of cheaper stuff). In my experienced, frames like this are found at bike shops, where they go when the owner brings 'em in to file a warranty claim. Were these failures sudden? Possibly. The difference, as I see it, is that the rider (luckily) can walk into the bike shop carrying his/her frame, and the frame looks solid and straight from a few yards off. Bustedcarbon.com shows us frames that are sheered in half, sometimes from JRA incidents.

    I get it that bustedcarbon is a site designed to sensationalize the "dangers" inherent in a particular material. Still, I challenge anyone to create a bustedsteel website to rival it; you can find a lot of busted steel, but the failures featured there would be difficult to sensationalize.

    I also get it that not all carbon is created equal, but with the demand for affordable carbon frames creating a proliferation of shiny plastic hand grenades being ridden by hamfisted neophytes who don't own torque wrenches, I have become concerned. Cheap steel frames being ridden by those same ppl are mostly just going to be heavy, and that doesn't bother me as much.

    Long story short, carbon fiber bikes and components are here to stay, and while I don't ride any, I don't necessarily want to discourage others from doing so. But, when safety is at stake, it's very important to make sure we get decent stuff and ensure that it's installed properly. As for me, I'm gonna keep it steel...

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    1. I enjoyed reading your comment about the "old" Schwinn brazed/electro-forged frames. I still ride a Schwinn Traveler that was bought new here in Hemet back in 1972. I owned a Paramount back then but needed a sturdy commuter.

      This bike started out as a one-speed with 26" welded steel rims. In the early eighties, I strung the Union front and hub and Bendix back hub with nice, light, 27" Weinmann aluminum rims. I removed the fenders and chainguard,cut off fender mounts and guard lug leaving only the mounting for a rack. The kickstand and its housing were taken off and a small spreader plate was welded between the frame tubes to maintain rigidity near the crank hanger. I lightly shaped and rounded off all of the roughly finished edges on both frame and forks. I went through several handlebars ending up with what I recall was Wald's Model 105, a nice broad old-time design
      with a light raise to the grips which run parallel to the frame. The Bendix brake is original, needing only 2 sets of shoes and 1 retarder spring in 40 years of continuous day to day riding. The Union front hub races are still 'smooth as a babie's bottom.' The frame is a rich electric blue. Forks and crank are Astabula with the stem a vintage SR aluminum. This model of Schwinn with its brazed frame and slack frame angles makes a classic 'fixie'. I've got an old style clover-leaf 46 tooth sprocket up front with an 18 tooth driver on the Bendix which, with the big wheels, finds me running just under 16 mph with enough reduction to hump it over hills and tackle mild grades. A great bike. Tough as a battleship but elegant at the same time.

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  26. One of the most common phrases in bicycle mechanics is "You rode your bike like this?!!". I've said it. It's been said to me.

    Steel frames give warning before they break. No lump of steel has the ability to alter human cognition. If a rider can't heed the warning that is not the fault of the material. And the material that gives warning is still preferable to the material that does not.

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    1. except that i've seen steel frames fail without warning. its not about the material -- its about engineering and accumulated fatigue/damage.

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  27. What about aluminum? I've got a folding bike with an aluminum frame, and that thing is a freaking tank - pretty sure it will outlast me!

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  28. I had a gradual failure of a Raleigh frame (the Japanese Raleigh, from the early 1980s). The tubes were very thin and I had clamped the downtube in a rooftop carrier. The dent in the downtube gradually turned into a crack (thinking back on it, I might have felt some sway when pumping). Fortunately, I noticed the crack before it worked its way around the tube and the bicycle collapsed during a ride.
    I agree that the emphasis on frame material is mostly marketing, mainly to justify the greater weight of steel.

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    1. I have been more receptive to the marketing that urges me to purchase the metal thing over the plastic one.

      I've ridden frames of every material, from high-ten clunkers to titanium, to whatever ya wanna call Kabuki Submariner or a Jamis Eclipse when it had carbon tubes and steel lugs. Ridden em all, but i've only owned steel bikes (with 2 aluminum exceptions...times were hard). Steel has always felt and performed the best for my tastes and preferences.

      Beyond all the recent claims that "CF will outlast 'em all, and we have computer programs to prove it"--I say, time will tell-- I could never imagine myself paying green money for a plastic bicycle. The fact that carbon has proven to be rather sketchy thus far certainly makes me even more skeptical, but I'm willing to concede that they've been improving CF tech in leaps and bounds lately; maybe the new ones won't snap like so many of the old ones did. But no amount of promises, marketing, or technical improvements is going to change the fact that a few grand is a lot of paper for a lil bit of plastic...

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    2. with all due respect, i doubt you ride the kind of steel frames i rode/ride. custom/triple butted skinny tubing is prone to breakage. quality monocoque carbon, not so much.

      on the other hand its very easy to chip or crack carbon fiber. i once broke a frame just by have the damn thing fall over! calfee repaired it and i've put 20K on it since then.

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    3. Anon4:19-
      I haven't owned a whole lot of ultra-lightweight steel bikes, but I've still got at least one triple-butted oversized steel tubed mountainbike. Not very lightweight, that one, but it's a tank.

      I've test-rode many high end lightweight bikes, and been around for a number of warranty situations when I worked at a bikeshop. Every type of frame fails. I've seen steel that's been cracked, I've seen aluminum that snapped and ended up really bent-up and scary-looking, but the only frames/forks that i've seen bust into separate pieces have been CF-- mostly expensive Bianchis from about 5 years ago. (Which is when I worked at a shop, which sold Bianchis. Not picking on that brand; we just handled warrantees for them....)

      My point from 04/16 at 11:13 was more that I don't want to pay good money for a plastic bike, even if the claims that it won't snap under my weight are true. I'm skeptical, but not incredulous, about the new claims, but it's a moot point: when we're talking about bikes, I prefer everything but the grips/tape, tires, and saddle to be made out of metal.

      -rob

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  29. Speculation...But part of what may fuel the theory of CF failing more "catastrophically" is due to frame design rather than material. Most newer CF frames are monocoque designs where the entire structure is dependent on the integrity of the entire piece.

    Joined tube frames like metal ones however have a little more redundancy built in to their construction. So you can have one tube detach from another without the entire structure failing. Of course, this is not always true. But I've seen a fair number of steel frames where one weld brakes and the frame basically stayed in one piece where CF failures tend to be one big break resulting in the entire frame breaking up. (But this is ancedotal rather than data of course)

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  30. More speculative theories...
    I suspect a lot of the difference people see is between superlight designs versus basic overbuilt ones and not between the actual materials.

    I've bent cheap steel handlebars and kept riding. I've snapped nice superlight cromo bars that gave no indication they were about to fail and crashed.

    I've seen people riding old steel water pipe frames they didn't even realize had a failed weld.

    When you design a piece to work at the extreme limit of the durability of the material, failures tend to be sudden. When there's just a lot of extra material there because weight wasn't a high priority in the design, you tend to get more warning/time when things do fail.

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  31. I've never witnessed a sudden steel frame/fork failure, and the only sudden Carbon-Fiber frame failures I've seen have been subsequent to a crash. A crash-damaged CF frame sure looks worse than a crash-damaged metal one, but I'm not sure either are more usable....

    I've had carbon-fiber seatposts (USE, Easton, Look) crack, found on inspection and retired, and the seat tube of my Calfee cracked (found on inspection; repaired under warranty). I'd use a carbon-fiber frame/fork again (my favorite-handling machine of all time was a carbon-fiber bike), but I'm not so sure about seatposts, stems, and handlebars. They get banged around a lot, and are subject to clamping stresses that form a notch under less-than ideal circumstances.

    My lightweight handlebars get retired if I crash them regardless of their material (I've found CF bars to be too stiff for my comfort and have reverted to aluminum ones).

    I've cracked aluminum rims (all rear high-dish wheels--tubular (700C), and clincher (650B)), found on inspection, and retired a (rear) carbon-fiber rim after it developed an ominous creak and stopped holding true.

    I have seen a catastrophic aluminum crank failure (an older Sugino), which resulted in the shortest-radius u-turn I've witnessed and ended the rider's day (a long walk home with his crippled bike in the winter), and seen a rider's Cinelli aluminum handlebar fail (that caused a bad (injury) crash). the crank failure could probably have been observed--there was evidence of long use after it had cracked and before complete failure. The handlebar would have been tough to see--it broke cleanly at the reinforcement sleeve.

    The common factor in all of these failures is that they were lightweight parts designed for high-performance machines, balancing light weight with adequate strength and durability. Lightweight parts are designed to push the edges of durability in the search for light weight, and performance bicycles live hard lives. A minor manufacturing defect, or a bit of misuse (ding/notch/deep scratch/misaligned or bent axles), and the countdown begins.

    The takeaway message I get from my experience with bikes is to inspect your equipment regularly, particularly if you're a bigger/heavier/stronger rider riding on lightweight machines.

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    1. I'm not quite sure how many handlebars I've broken. A few. These days I replace them before they become too aged. I haven't fallen yet because of a handlebar.

      I've watched enough other riders break bars to regard it as normal. The most common response is a moment of surprise as the rider looks at the loose half-handlebar and cables in his hand. Then he says "Oh shit" and rides home at a reduced pace. Another response is to have a moment of surprise, look at the loose half-handlebar and reason "Oh noes!!! I am now Wile E. Coyote and I am over the cliff! Now I must fall!". And they do.

      Sure, if the handlebar breaks as you bang through a monstrous pothole or while coming down a one in four grade - then you will likely crash and nothing will stop it. But I've seen it often enough and most riders don't crash. The ones who crash have a very different look on their face as they prepare for the ride down.

      Many crashes are made much worse than they need to be. Mechanical failure alone is not a complete set of pre-conditions to cause a crash. I've broken cranks too, and watched others break cranks, and that is just a non-event.

      I snapped a stem once and stayed up. I can't even explain how that is possible. But it is possible.

      This is not meant to rag at Will - just one likely place to insert this. Things break. You do what you know to do to improve your chances and then you go ride your bike.

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  32. Beware some JRA stories (I was "just riding along" and BOOM!). I've been riding for around 35 years now (from age 4 until present,with the vast majority of those years off road and/or "rough" mtn biking),and I have personally snapped a few aluminum frames (with my heaviest self only ever being 160lbs),but have never broken a quality,non-department store steel frame,nor have I ever met anyone who knew anyone that did in all my cross country travels back in my long haul trucking days. Bent or warped? Yes,but rare. Broken? Nope.

    Like has been mentioned above,I've experienced the breakage of lightwieght COMPONENTS (rarely made from steel though..."light" is usually reserved for other materials),but never a frame. I'd be hard to convince...35 years and thousands of miles all over some of outr country's best trails with never having seen it would pretty much make anyone's mind up. Not saying it has never happened....but I'd raise an eyebrow listening to how,LOL!

    Obviously enjoyed this one,V,VERY thought and emotion provoking :)

    The Disabled Cyclist

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    1. It would be great to publish a compilation of stories actually called JRA Stories : )

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  33. If I had any real concerns about the durability of carbon fibre I sure wouldn't have been half a mile up doing spins in my gliding club's 14 year old 4500 flight hour DG-505 for my annual checkflight this weekend!

    The only structural failure I've ever personally experienced on a bike was a steel fork leg that started cracking below the lug on a circa 1980 Apollo. Since then I've beaten the hell out of a Cannondale M800 and track bike and a Kona cyclocross (the Kona has carbon fibre seatstays and fork) without having any failures so far.

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  34. This discussion make be glad my current bike is TI made for cyclocross!

    I think that the weight and .. enthusiasm has a lot to due with how well a bike lasts.

    At a little over 200 lbs, I'm now a careful (OK, more careful) rider. I've bent steal frames twice and broken and aluminum set of bars (side note: if a piece breaks off don't let go of it - that's what caused the crash.)

    A lot of bikes are designed for Lance, all 5'8, 150 lbs of him. I'm somewhat larger, with larger forces on the bike. That exceeds the design, and the bike bents or breaks. Material isn't as significant a factor. Of course weight x acceleration = force, so your mileage may vary.

    Now, a well built (or overbuilt) bike will probably last longer. Seems, to me more bike are race bikes. These are made as light as possible. And larger people get longer tubes, not thicker tubes. That's what makes the frame failures. Light bikes.

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  35. If you want to know a lot about steel tubing, failure modes and length of life, talk to some folks at any of the air museums who restore aircraft from the 20's and 30's and 40's. Most of the tubing used up through the 50's was 1020 steel. 4130 didn't come about til later. But steel does fatigue and can fail somewhat suddenly. Just not as suddenly as composite. CF hasn't been around that long. But what fails in CF isn't the carbon, it's the epoxy preg that it's embedded in, and that's been around for decades.
    Interestingly, the material used in planes that gives the MOST WARNING and the slowest degrade: Wood. Wood fails slowly. And it gets stronger as it ages instead of weaker. You just have to keep it sealed up to prevent wood rot. But varnishes - including epoxy - are SO much better than they were 80 years ago, that planes being built on plans that are 80 years old will likely last a hundred years.
    BTW, wood rims feel great! Ask anybody who has ridden them.

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  36. Just to add another perspective to the whole "carbon fails suddenly, steel fails slowly" thing: In my limited experience I've seen lots of steel fail and lots of carbon fail. Every steel failure has been slow (i.e. you could ride to a stop and not crash) but has happened while "just riding along." All the carbon failures have been during crashes in races and were instant ride-enders. This is the common way of frame failures and it SOUNDS bad for carbon. But think about it. Most of the time when carbon fails it's due to a crazy hard impact caused by a crash. In other words, you're going down anyway, what does it matter if your fork cracks too? Whereas with a "just riding along" failure, you might end up going down for no good reason. Basically, any crash on the road that I walk away from is a miracle and I'm happy no matter the state of my bike. So, carbon isn't any more likely to make you fall, and that's all that matters.

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  37. The failures mentioned sounds like poor craftsmanship. Steel is much harder to work with correctly than most ppl realize. If u order a steel frame, ask the builder about his metallurgical training. Personally I would prefer to buy a steel frame from Taiwan than the hipster with a brazing torch...

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  38. old discussion but here is my 2 cents,,
    i see a lot of frame, fork and part failures , the steel frame failures are usually down to over ambitious tube selection combined with too much heat , builders are under pressure to get weight down and thus select tubing that has walls that are too thin for the the amount of heat the builder is using, one of the finest i have seen in action were Wester ross , they really knew how hot to take a certain material, another contributer is parts fitting , ,over clamp a front mech and you will have caused a weak spot , carbon is a whole other ball game , considering how new the tech is it still has a long way to go , i know what you meen about the "dead, hollow feeling" ,i hate riding carbon frames, although i do like a carbon fork on steel / aluminium alloy frames.
    the fact is that Carbon composite is more efficiant from a riders(engines) point of view but i still ride steel , vintage british steel at that , but if i were to start racing i would use a carbon frame , i have had carbon bars and a seat post fail on me but they were slow failures of the delamination type and were eventually tracked down to the carbon getting grease on it, this is my biggest gripe with CF , its far too temperamental for everyday use , dont get grease or oil on it, always use a torque wrench and grip paste when assembling etc, no thanks . you pays your money...

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  39. I haven't read all the comments here so excuse me if i'm repeating, but in my experience, carbon failures actually do happen gradually, you just need to look for cracks. A crack that develops over time will break suddenly, usually in high stress areas near joints (corners). High impact will cause sudden failure at weak spots that are often not visible, but this is usually only applicable to mountain bikes and downhill frames.

    Alloy frames often show slight discolouration or cracking at high stress points. Finding These stress points in steel can sometimes be more difficult but it is possible to note a audibles difference near stress points when struck gently.

    The best way to look for this is to maintain your bike. Just a wash every now and them will get you looking over the frame, check it well every few months or after hard knocks, and on road frames, try loosen up a bit, let your body absorb the bumps.

    PS. Dropping your chain kills alloy and carbon frames. Chain suck, well,sucks. Try setup your drive trains to avoid such things.

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