Bicycle Mechanics - Fork materials

Searching the archives is problematic... mostly salad and recreational posting. Hence I'll summarize what I learned/read.. to date.

After hashing this thread out.. what I meant to focus on is the FAILURE MODES of different fork materials. Common internet platter is thrown around like male cow dung on the subject.. to date I have NOT found a good read on this.

When bike people of experience such as FBinNY question the durability of carbon steer tubes.. that to me is of note. This matches concerns I've found with other bike repair/avid riders of long experience.

Reason for my interest in this subject was to talk myself into a carbon fork with alloy steer... from a brand via a name discount bike online store. I could find no record online of anyone having performance issues with them. Contacting another online source raised a red flag to my way of thinking-- Warranty issues.. details of which were not given when requested. From that.. I take it to mean if one has issues your then attempting to deal with someone who fabricated said fork from over the pond. Good luck there.. so it seems.

I'd offer even going out for a bike ride is likely more dangerous than mounting almost all of the carbon forks (w steer steer tubes) manufactured. Yet the failure mode of carbon forks most often gives no warning.. your down. Yes other fork materials fail.. but the postings of carbon failures is so numerous around the net. Steel forks for instance have been around for a century.. on millions of bikes.. those failures are seldom found looking over the net. Just seems to me.. carbon failure is percentage wise too high.. for a 235 lb rider like myself. Bike riding means risk of injury.. adding a carbon fork is just one variable I'll avoid.

Marketing.. is today's world. The hype and nonsense of websites.. saying allot.. often meaning little. Another item is the testing of components with said manufacturer paying for.. or doing that testing. That testing is nearly meaningless for me. I've no doubt some are interested in brand promotion.. the integrity of their name and products. Yet per unit cost.. the bottom line rules.

http://www.pardo.net/bike/pic/fail-001/FAIL-164.html

SortaGrey, I think you'll recieve much the same type of opinion as in your previous fork material thread. Again, regardless of fork/steerer material there have been failures across the board.

Brad

Brad my idea was a discussion more in-depth on how to sort the merits of brand names... aftermarket forks.. some idea of expected failure rates. Differences in carbons etc. Just looking to dig a mite deeper.. from knowledgeable experienced riders.

I have 3 bikes, two with carbon forks with alloy steerer (why does bike industry say "alloy", doesnt that just mean aluminum of some sort?), and one 80s schwinn with steel fork and steerer. I have never given failure much thought. One of my bikes is a 9 year old cannondale CAAD7 with the slice carbon fork that came with the bike. Their focus now on carbon bikes notwithstanding, I think it fair to say that C'dale can be considered a gold standard when it comes to aluminum so I am inclined toward confidence in the steerer that I have. The other fork is a Sette carbon fork I bought off pricepoint to replace a steel fork I had destroyed (through no fault of the fork or its manufacturer). I have no clue who made the fork or steerer so I suppose that's a risk but its served me well for 6 years of regular commuting so I have no complaints (for three of those years I weighed between 235-245 before I lost a bunch of weight).

I haven't done alot of research on who is testing what, but I know alot of testing is done on tires (rolling resistance, etc) so I infer that bike industry does a fair bit of testing to improve performance without sacrificing durability across the board. Here is one link to a velonews q&a with Lennard Zinn wherein a bunch of manufacturers provide comment on their standards. http://velonews.competitor.com/2002/12/bikes-and-tech/technical-faq/technical-qa-with-lennard-zinn-carbon-forks-2_3270.

As for steel fork suppliers, if I were in the market, I'd probably start with some of the boutique online providers specializing in steel frames-- e.g. Surly, Salsa, Soma. These are not custom shops (frames made overseas) but they have reputation for quality at affordable price, and they use quality steel -- high end Tange and Reynolds mainly (I have Soma bike with my Sette carbon fork).

But when push comes to shove, there are no guarantees in life. Companies known for quality on occasion produce a lemon and when buying after market parts you can never eliminate all the quality unknowns. But I am more likely to get hit by a car while out for a ride than I am to suffer a sudden fork failure (in 13 years of commuting I have been hit 4x but never suffered fork failure). In both cases, I take what precautions I can and then don't worry about it.

(why does bike industry say "alloy", doesnt that just mean aluminum of some sort?),

An alloy is basically a mixture of two or more metals. In the bike industry, "alloy" tends to be used to describe parts made from an alloy that consists mainly of aluminium (i.e. "aluminium alloys"), despite the fact that a lot of steel bike parts are made from alloy steels, and quite a lot of titanium parts are made from titanium alloys.

Your fixation on fork failures is interesting. Do you drive a car? Have you ever experienced a front wheel bearing or steering linkage failure? These can and do lead to complete loss of control and almost always cause a crash but you still drive 60+ MPH for thousands and thousands of miles and neve give it a thought, event though these failures can happen. It's just that they are truly rare events as are fork failures from reputable makers.

As to "Gold Standard" components, I think the big name manufacturers are far more likely to do adequate testing and insist on (and inspect) proper QC procedures from their in-house plants or outside suppliers. They have a reputation to maintain and much more financial liability than a garage operation in Asia.

Cannondale, Trek, Specialized, Surly (a division of QBP), Easton, Fuji, Bontrager (aka Trek), etc are all reliable and careful companies. That said, anyone can and will make a defective part on occasion. It's just far less likely from one of the well-known companies.

Your fixation on fork failures is interesting. Do you drive a car? Have you ever experienced a front wheel bearing or steering linkage failure? These can and do lead to complete loss of control and almost always cause a crash but you still drive 60+ MPH for thousands and thousands of miles and neve give it a thought, event though these failures can happen. It's just that they are truly rare events as are fork failures from reputable makers.

As to "Gold Standard" components, I think the big name manufacturers are far more likely to do adequate testing and insist on (and inspect) proper QC procedures from their in-house plants or outside suppliers. They have a reputation to maintain and much more financial liability than a garage operation in Asia.

Cannondale, Trek, Specialized, Surly (a division of QBP), Easton, Fuji, Bontrager (aka Trek), etc are all reliable and careful companies. That said, anyone can and will make a defective part on occasion. It's just far less likely from one of the well-known companies.

Fixation? Not so.. but trying to get more information... etc than the norm. What is wrong with an in-depth search for more info? Nothing.

Hard to find objective data on the net.... or anywhere for that matter.

As always.. the some fail to grasp the situation.. or what is being asked. Glossing over with an opine is not the same as looking for knowledge.

Tell the people injured by fork failures their 'rare'. Does it matter ...then? Obviously not. Nothing between a rider's person and the road when a fork gives way... somewhat different accident event.

I've ridden on a Nashbar carbon fork and an Easton aftermarket fork. Both held up fine. I'm now running a Salsa steel fork on my touring bike and a Salsa in-house full carbon fork on my 'cross bike. I trusted the Nashbar fork the least and used it for a year before I could replace the entire bike.

The gold standard for forks is name. Any of the major fork manufacturers are going to have a better quality check than the online cheap stuff. In general, these forks are carried by reputable LBS's because the LBS is also lending it's name to the quality of the products they sell and certainly have more to lose than a knock-off Chinese company.

[QUOTE
Hard to find objective data on the net.... or anywhere for that matter.
[/QUOTE]

The reference to ATM in the Zinn Q&A I posted got me curious. One search came up with this so I guess if you want to do more research, you could spend some money on the test reqs.

http://www.astm.org/Standards/F2273.htm

I also found some references to testing labs like this http://www.microbac.com/testing-services/bicycle-frame-component-testing/, and testing papers like this one http://www.oemcarbon.com/2012/08/fatigue-and-impact-behaviour-of-carbon-fibre-composite-bicycle-forks/

and this one: http://www.wpi.edu/Pubs/E-project/Available/E-project-042910-084057/unrestricted/Fatigue_Analysis_of_a_Bicycle_Fork.pdf.

So if you are inclined toward caution, I infer from fact that I found these various things among the top results with one google search, that there are both bike industry-affiliated and independent resources available to get some of the data you seek.

Fixation? Not so.. but trying to get more information... etc than the norm. What is wrong with an in-depth search for more info? Nothing.

Hard to find objective data on the net.... or anywhere for that matter.

As always.. the some fail to grasp the situation.. or what is being asked. Glossing over with an opine is not the same as looking for knowledge.

Tell the people injured by fork failures their 'rare'. Does it matter ...then? Obviously not. Nothing between a rider's person and the road when a fork gives way... somewhat different accident event.
OK, while you are at it get the data on stem and handlebar failures. These have the same consequences as a fork failure.

I once had the handlebar clamp bolt on a stem break and I was on the ground instantly. Fortunately it was at a walking pace as I had left a traffic light so my injuries were very minor but, at speed, it would have been far different.

OK, while you are at it get the data on stem and handlebar failures. These have the same consequences as a fork failure.

I once had the handlebar clamp bolt on a stem break and I was on the ground instantly. Fortunately it was at a walking pace as I had left a traffic light so my injuries were very minor but, at speed, it would have been far different.

Yeah, lots can go wrong on a bike and if its front end, bad things happen. Hell, even a bad blow out of front tire can be catastrophic. Why do we even leave the house? :). For me, the only thing thats ever snapped on my bikes was a steel chain stay. That made me stop but I was not in danger of calamity.

The thread concerning the Trek with the broken steer tube touched on some interesting points.. issues with bike forks.

Like many.. I don't trust carbon forks. Understand.. I know many do. Just the end of a carbon fork is the icicle break and your toast. Granted a seldom occurrence.. I just can't get by it's 'failure mode'. And they manufactured in a world where IMO QC is more a function of 'getting the pieces out' than the future safety of anyone using a product. I requested warranty info from one online peddler.. where the word 'warranty' is NOT anywhere on their word-some website. Reply was 'full warranty'.. my replies for further info only got the 'rope a dope' routine.. the RED flag in my view. They even went to the extent of banning me from purchasing any item from them. That tickled me... finding the nerve with almost no effort.

These after-market carbon's... I wonder if anyone in the industry actually tests them? This I doubt in a cost driven market place. Does buying one from an established name maker insure some degree of added safety? Anyone know of the expected failure rates? I know almost nothing of carbon forks... what weaves etc. Many knowledgeable riders have confidence in them.. I'm looking for more than just the blanket 'thumbs up'. How to determine what is acceptable risk for a heavier (230's) rider.............. I still remain open to the idea of trying one.

Aluminum forks. Same set of inquires as above... & in regards to steer tubes of that material failing.. I'd suggest this: whose aluminum? That metal sees constant recycling.. I suspect metal contamination during that process compromises strength life [?].

SO.. what fork makers are the 'gold standard' for doing it right?

Steel forks... a good weight to strength compromise.. who makes??

Methinks you have an agenda...Also, you have some pretty serious misconceptions regarding QC in the modern era.

Are you willing to pony up the cash to have a custom made fork made out of light,
resilient, but expensive, Steel parts?

then you and a custom framebuilder of your choice can begin your discussion..



Most of the Business is in Price Conscious bikes , but they want the latest stuff..

so the companies contract out to Asian companies the make the parts in volume .
maybe 1 in a 1000has a defect, so then the recalls take back the other 999
to be on the liability safe side.

.........but forks of various designs, materials, and manufacturer get recalled on a pretty regular basis.

https://www.google.com/search?q=bicycle+fork+recalls&aq=f&oq=bicycle+fork+recalls&aqs=chrome.0.57j0.11987&sourceid=chrome&ie=UTF-8

This has been the case going back to the first alloy fork designs.

But it is quite possible that it is more related to the greater emphasis on
consumer safety and recalls in the era of alloy, carbon, and suspension
fork designs than to the materials involved..

In short, I don't know of any reliable data.

http://www.cervelo.com/en/support/recalls.html
http://velonews.competitor.com/2011/02/news/felt-recalls-some-road-bikes-due-to-potential-fork-breakage_161173
http://thebicycleplanet.com/articles/rockshox-inc.-announces-recall-of-bicycle-forks-pg56.htm
http://www.cpsc.gov/cpscpub/prerel/prhtml12/12149.html
http://www.cpsc.gov/cpscpub/prerel/prhtml12/12281.html

"Methinks you have an agenda...Also, you have some pretty serious misconceptions regarding QC in the modern era."

That.. first part is just nonsense. Just an honest inquiry. What is wrong with asking a few quesitons? Does everyone around here work for the bike industry..... :) Ask a few hard questions and the riot squad starts in. :rolleyes:

My views of QC in this era are right on. You have another view.. fine. We'll agree to disagree on that pt.

Why not.. rather.. just discuss the tech merits of forks flavors? THAT..was MY intent.

I fail to understand.. how a carbon fork just icicles. I've little practical knowledge of them.

I fail to understand.. how a carbon fork just icicles. I've little practical knowledge of them.

They don't actually fail like an icicle - ice is brittle and shatters by fast crack growth, carbon-fibre reinforced plastics (to give their full name) are fairly resistant to crack growth. The issue with carbon forks is that a metal part will likely give some indication that it's going to fail, often in the form of a visible crack or some sort of ductile deformation, while potential failures in carbon components aren't always as easy to spot.

note the current trend is to use the design flexibility of CF composites , and increase the diameter of the lower race
to something like an inch and a half , and retain the 1 1/8th up top.

Dont like chasing the high tech latest thing trend ? lots of 1" threaded steel fork bikes are still on the road.

perhaps someone makes a 1.125" fork steerer that is Butted at the bottom, like the steel 1" steerer's are.

A friend of mine tested fatigue failure of carbon composite materials for aircraft design and came up with 400,000 flexes before failure, and that number seemed similar to what I've seen for bicycle carbon fiber. Fatigue limit for aluminum is on the order of ten million cyclic stresses if I recall correctly.

That's all more vague than I'm comfortable with, and it's not really a hard limit of stresses before failure but more like a probability of failure that increases as the number of cyclic stresses increase. Does anyone know of more specific and reliable numbers for fatigue failure, comparing carbon fiber, aluminum and steel? You won't hit the limit with aluminum with the stresses from normal riding but the 400,000 for carbon fiber seems approachable given enough time.

Where did he publish his findings?

Like SortaGrey, I'm not a fan of carbon steerers (carbon blades are OK though). My reasoning is similar to his also. When considering the safety of anything I use an analysis that factors both the likelihood and consequences of failure. Where the consequences aren't likely to be serious, I'll accept a high rate of failure, however as the consequences become more severe I try to bring the likelihood to as close to zero as possible.

Given that a fork failure at the base of the steerer is probably the most catastrophic of all possible structure falures on a bike, I stay with the proven reliability of butted steel steerers for personal use.

That said, not all carbon fork failures are the same. Some manufacturers employ a safety net approach, usually using a few layers of fiberglass weave at the crown. This has enough flex to tolerate the bending that shatters carbon fiber and can hold the fork together a while. It's an old tried and proven approach going back to the use of wooden dowels in the bases of steel steerers.

I suspect that the biggest issue with carbon forks is that of sourcing and quality control. While I trust that the reputable firms have decent quality control standards, and choose and monitor their vendors carefully, I'm not sure this applies to all, and especially unknown suppliers. Then there's also the lack of long term history about product life under various conditions. If a given fork is OK for 50,000 miles of road use, how many of those can be on Pave?, How hard an impact from a deep pothole, unseen bump, or light impact can the fork tolerate?, if within the limit, how many severe jolts is too many?

When I ride, and descend at 40+ mph, I don't want to be thinking about my equipment. I ride for pleasure and trust in my equipment ranks much higher than any possible weight savings ever could.

An alloy is basically a mixture of two or more metals. In the bike industry, "alloy" tends to be used to describe parts made from an alloy that consists mainly of aluminium (i.e. "aluminium alloys"), despite the fact that a lot of steel bike parts are made from alloy steels, and quite a lot of titanium parts are made from titanium alloys.

pure aluminum is butter soft in thin walls.

the auto industry liked to call aluminum alloy wheels "mags" because many of them contained some small percentage of magnesium, but in fact virtually all of them are mostly aluminum.

here's a typical aluminum alloy, 6061...

Silicon (http://en.wikipedia.org/wiki/Silicon) minimum 0.4%, maximum 0.8% by weight
Iron (http://en.wikipedia.org/wiki/Iron) no minimum, maximum 0.7%
Copper (http://en.wikipedia.org/wiki/Copper) minimum 0.15%, maximum 0.40%
Manganese (http://en.wikipedia.org/wiki/Manganese) no minimum, maximum 0.15%
Magnesium (http://en.wikipedia.org/wiki/Magnesium) minimum 0.8%, maximum 1.2%
Chromium (http://en.wikipedia.org/wiki/Chromium) minimum 0.04%, maximum 0.35%
Zinc (http://en.wikipedia.org/wiki/Zinc) no minimum, maximum 0.25%
Titanium (http://en.wikipedia.org/wiki/Titanium) no minimum, maximum 0.15%
Other elements no more than 0.05% each, 0.15% total
Remainder Aluminium (http://en.wikipedia.org/wiki/Aluminium) (95.85%–98.56%)


so, all the non-aluminum stuff in it combined is less than 5%, maybe even less than 1.5%

An alloy is basically a mixture of two or more metals. In the bike industry, "alloy" tends to be used to describe parts made from an alloy that consists mainly of aluminium (i.e. "aluminium alloys"), despite the fact that a lot of steel bike parts are made from alloy steels, and quite a lot of titanium parts are made from titanium alloys. Right, for steel alloys the say "cromo" or just use the branding (Reynolds 853 or whatever) but for alu sometimes they'll use the specific alloy (6061, 7075, etc) but more often they say alloy (ally nipples, alloy steerer, alloy seatpost) mostly to generally distinguish from either brass (nipples) or carbon. Never (or at least rarely) is a bike component made from a steel alloy referred to generically as alloy.

the auto industry liked to call aluminum alloy wheels "mags" because many of them contained some small percentage of magnesium, but in fact virtually all of them are mostly aluminum.


To further complicate things, british convention is to call the damn things "alloys", as in "watch out, you're gonna kerb the alloys!"


but more often they say alloy (ally nipples, alloy steerer, alloy seatpost) mostly to generally distinguish from either brass (nipples) or carbon.

Slightly ironically, brass nipples could be referred to as "alloy" as well, brass being an alloy.

OK, while you are at it get the data on stem and handlebar failures. These have the same consequences as a fork failure.

I once had the handlebar clamp bolt on a stem break and I was on the ground instantly. Fortunately it was at a walking pace as I had left a traffic light so my injuries were very minor but, at speed, it would have been far different.

There's a big difference between a handlebar, stem or top of steerer failure vs. a steerer/crown failure. The latter is an instant faceplant, as the front wheel falls away and the head goes to ground. The first may cause a crash, but not of the same kind and the consequences tend to be far less critical.

For comparison, I'd just like to say Trek STP400.

For comparison, I'd just like to say Trek STP400.

Huh?

Huh?

The Trek STP 400 was Treks go at a carbon soft tail mountain bike. The idea of a soft tail is that rear of the bike has a shock but no hinging point. It uses the flex of the frame material to actuate the shock. Trek used the flex of carbon fiber chain stays to actuate their suspension. While I don't know the exact specs, one would have to assume this design is going to see more cycles and more flex than a typical road bike fork.

the auto industry liked to call aluminum alloy wheels "mags" because many of them contained some small percentage of magnesium, but in fact virtually all of them are mostly aluminum.
The first light weight cast wheels were indeed magnesium alloy (the metal was mostly magnesium with small amounts of alloying elements) due to it's light weight but the high cost made them unattractive for wider use so cast or forged aluminum alloy replace magnesium as the metal of choice. However, the name "Mag" stuck even when applied to wheels made of other metals.

The first light weight cast wheels were indeed magnesium alloy (the metal was mostly magnesium with small amounts of alloying elements) due to it's light weight but the high cost made them unattractive for wider use so cast or forged aluminum alloy replace magnesium as the metal of choice. However, the name "Mag" stuck even when applied to wheels made of other metals.
Hell, back in the 80s, we called the plastic wheels on our BMX bikes mags!

Hell, back in the 80s, we called the plastic wheels on our BMX bikes mags!
Hey, you're just a kid! :rolleyes: I remember a friend in 1964 who had Craegar "Mags" on his brand new '64 Vette and they were already aluminum. By then, true magnesium Mags were pretty much limited to competition cars.

They don't actually fail like an icicle - ice is brittle and shatters by fast crack growth, carbon-fibre reinforced plastics (to give their full name) are fairly resistant to crack growth. The issue with carbon forks is that a metal part will likely give some indication that it's going to fail, often in the form of a visible crack or some sort of ductile deformation, while potential failures in carbon components aren't always as easy to spot.

That is what I thought too.. after seeing a golf shaft shattered by much intentional abuse yrs ago. I hung the icicle label on due to a couple online reports of bikes going down the rd and the carbon blade just snapped off. One instant your riding.. the next the guy woke in the ER.

I don't think it's fair.. a suggestion.. to bring brand names into the discussion. NOT wanting to give anyone some idea one brand is more suspect than another. Who knows.. or could accurately prove that anyway.. especially by online "data".

I already decided prior to this thread not to ride carbon forks. I am now in the situation on one build that a potential buyer WANTS a carbon fork. Of course one online source known for good deals has one. I'm not inclined to mount one.. but decided to have a much harder objective look at them.

Understand well.. not at all.. what's the right wording.. judging anyone's choice of fork material. I did purchase a near new brand name fork online.. frankly I was impressed with it's construction.. had a serial number on it too. But the threaded alloy steer tube was a might short though. A no go for the bike in question... that kind of buy comes along rarely I think.. quality, low useage and cost.

Amen to the comments per all the fork recalls. I get to the LBS rarely... and I've seen two notices per fork recalls. My cynical personal comments per modern QC go to those events... and while yes QC in some areas today are superior.. just as many 'shops' are 'get it out the door' operations. Nuff whining on that... by me anyway.

I do ride a little used aluminum fork.. that bike spent all it's time prior to my purchase in a garage. I can see no real difference to it and the steel one on a near identical steel framed MTB... except of course the M700 weighs about 9 lbs less. But from what I can determine looking around.. aluminum gives notice to failure.. and the likelihood your on your face in an instant is very low odds. IF you can find different.. I for one would like to hear that.

Purely opine of mine.

The aftermarket no name forks.. are not worth the risk. Their might well be decent people making them.. but their lower cost means the manufacturing corners get rounded off.. ie: again 'get them out.. piece counts'. Find yourself injured.. who pays? NOT the marketing company that sold it.. that is for sure. Like I discovered.. one I found didn't even have the kahoona's to admit this. Price means nothing given the nature/importance of a fork's integrity. Younger people.. like me yrs back too.. seemingly IMO are taking unnecessary risks ...to save what? Yes anything has risk.. but again IMO... there's little protection/insurance.. piece of mind riding no name mass produced bike forks. END. :thumb:

Am looking for a steel or new/near new al fork (brand name).. 8.5"--+.. 1" threaded steer tube. Lighter.. better. PM me if you wish.

t.

Purely opine of mine.

The aftermarket no name forks.. are not worth the risk. Their might well be decent people making them.. but their lower cost means the manufacturing corners get rounded off.. ie: again 'get them out.. piece counts'. Find yourself injured.. who pays? NOT the marketing company that sold it.. that is for sure. Like I discovered.. one I found didn't even have the kahoona's to admit this. Price means nothing given the nature/importance of a fork's integrity. Younger people.. like me yrs back too.. seemingly IMO are taking unnecessary risks ...to save what? Yes anything has risk.. but again IMO... there's little protection/insurance.. piece of mind riding no name mass produced bike forks. END. :thumb:


You should certainly ride what you feel safe on, but I havent seen any reason in this thread or anywhere else to feel that any material is more or less likely to fail. I will say that your estimation of risk is almost certainly not accurate from a quantitative standpoint. Risk in this case is simply a function of number of items sold and incidences of catastrophic failure. Given shear numbers of items available in market, the risk that you will come to own a component that fails catastrophically is without doubt very low (I would guess some fraction less than a 1/10 of 1% of components will fail but thats a guess). That said, risk is certainly not zero, and any part of risk calculus is always the potential impact of failure even if risk is low; and indeed potential impact of a failed steerer or fork is high. So if you fear it, you won't feel comfortable riding so wont ride. So I would not presume to try and convince you to ride carbon stuff. Hell, I tend to steer clear of carbon components that require other components be clamped to them (seatposts and steerers) because I fear I will damage them by over-tightening clamps -- but thats more a reflection of my lack of confidence in my competence than in the component itself.

Frankly, my anecdotal experience suggests that its just as plausible that we are at greater risk from metal failure than from carbon failure. I have had various pieces of bikes fail -- a steel chain stay on a Jamis frame cracked at weld (Jamis gave me warranty replacement frame), a Trek alu mountain bike frame cracked in middle of the downtube (I was not original owner so no warranty), and I had alu flange of a shimano hub crack. So metal stuff from big, reliable makers fails. So far I have not had any carbon components fail, but I certainly believe they do too, but for me, at a lower rate than carbon stuff . My anecdotal experience does not valid data make so is no more meaningful from a data analysis standpoint that your concerns about carbon, and at end of day you could be right about your carbon concerns.

I will lastly note that I actually take comfort in recalls I am aware of (Felt, Specialized) rather than view them as indicator of greater likelihood of failure; to me voluntary recalls mean companies are paying attention to quality (and recalls are cheaper than risk of litigation). I suspect recalls are based on the company's quantitative assessment that some specific lots of their production runs don't meet whatever failure standard they have set. So they are taking steps to ensure things get pulled at early sign of any issue even if the chance that an owner of that specific component actually experiences a failure remains very low -- albeit higher than for components that meet the company standard.

That is what I thought too.. after seeing a golf shaft shattered by much intentional abuse yrs ago. I hung the icicle label on due to a couple online reports of bikes going down the rd and the carbon blade just snapped off. One instant your riding.. the next the guy woke in the ER.


Well, the blade didn't "just" snap off - the carbon would almost certainly have been failing for some time. It's just that the imminent failure wasn't obvious like it probably would've been on a metal fork. Fibre-reinforced composites are generally very good at dealing with cracks.

Well, the blade didn't "just" snap off - the carbon would almost certainly have been failing for some time. It's just that the imminent failure wasn't obvious like it probably would've been on a metal fork. Fibre-reinforced composites are generally very good at dealing with cracks.

Bold print highlight mine.

I'd certainly agree. Yet in the instance/s I've read per those blade failures... no performance issue was felt.. ie: front wheel felt normal riding. But who knows on that count...

Would think... metal blades would bend before separating.. [?]... some handling issue would show.

You should certainly ride what you feel safe on, but I havent seen any reason in this thread or anywhere else to feel that any material is more or less likely to fail. I will say that your estimation of risk is almost certainly not accurate from a quantitative standpoint. Risk in this case is simply a function of number of items sold and incidences of catastrophic failure. Given shear numbers of items available in market, the risk that you will come to own a component that fails catastrophically is without doubt very low (I would guess some fraction less than a 1/10 of 1% of components will fail but thats a guess). That said, risk is certainly not zero, and any part of risk calculus is always the potential impact of failure even if risk is low; and indeed potential impact of a failed steerer or fork is high. So if you fear it, you won't feel comfortable riding so wont ride. So I would not presume to try and convince you to ride carbon stuff. Hell, I tend to steer clear of carbon components that require other components be clamped to them (seatposts and steerers) because I fear I will damage them by over-tightening clamps -- but thats more a reflection of my lack of confidence in my competence than in the component itself.

Frankly, my anecdotal experience suggests that its just as plausible that we are at greater risk from metal failure than from carbon failure. I have had various pieces of bikes fail -- a steel chain stay on a Jamis frame cracked at weld (Jamis gave me warranty replacement frame), a Trek alu mountain bike frame cracked in middle of the downtube (I was not original owner so no warranty), and I had alu flange of a shimano hub crack. So metal stuff from big, reliable makers fails. So far I have not had any carbon components fail, but I certainly believe they do too, but for me, at a lower rate than carbon stuff . My anecdotal experience does not valid data make so is no more meaningful from a data analysis standpoint that your concerns about carbon, and at end of day you could be right about your carbon concerns.

I will lastly note that I actually take comfort in recalls I am aware of (Felt, Specialized) rather than view them as indicator of greater likelihood of failure; to me voluntary recalls mean companies are paying attention to quality (and recalls are cheaper than risk of litigation). I suspect recalls are based on the company's quantitative assessment that some specific lots of their production runs don't meet whatever failure standard they have set. So they are taking steps to ensure things get pulled at early sign of any issue even if the chance that an owner of that specific component actually experiences a failure remains very low -- albeit higher than for components that meet the company standard.

Well written... good pts.

This cynic writing now.. views those voluntary recalls in another light. These marketing companies are all about bottom line.. the legal dept simply pulls the cord and they recall. Some of this is covering their liability.. doubt a large percentage of those actually get replaced. Be interested on that count. But QC must be in place on forks prior to selling. Might well be a human element with 'doing what is right' also.. going to brand name integrity.

FBinNY said it.. I don't want to worrying about bike issues riding either. Considering the issue makes me redouble my 'taking a break' inspections. I make myself get off the bike more often now and enjoy the day.. etc.. more reflective... and going over the bike. This thread for me puts the fork issue in a much more informed light. Thanks to all who contributed.

Once broke a steel motorcycle frame. JRA, all of a sudden the rear end felt vague and bouncy. No warning. Heavy steel, blah, blah, blah. Obviously, I will never trust that dangerous material with my life again.

Once broke a steel motorcycle frame. JRA, all of a sudden the rear end felt vague and bouncy. No warning.

You'd probably have seen a crack if you'd inspected the frame before the failure, but I can't imagine most people inspect their motorbikes that closely. Even if you did, the layer of dirt that builds up on stuff might hide the crack, or you might mistake it for a scratch in the paint, plus if it's at a weld, it might not be particularly easy to spot anyway. The point is, there would have been a warning, but it's not a warning you'd have seen.



I'd certainly agree. Yet in the instance/s I've read per those blade failures... no performance issue was felt.. ie: front wheel felt normal riding. But who knows on that count...

Would think... metal blades would bend before separating.. [?]... some handling issue would show.

And there lies the rub, so to speak. Carbon can break suddenly while feeling normal and looking fairly decent, while metal would creak and/or crack visibly, if it didn't bend.

Once broke a steel motorcycle frame. JRA, all of a sudden the rear end felt vague and bouncy. No warning. Heavy steel, blah, blah, blah. Obviously, I will never trust that dangerous material with my life again.


but, broken, it just felt bouncy, it didn't drop your butt on the road at speed, no?

I have a vivid memory from when I was a kid riding in the '56 Chevy with my dad and the right lower A-arm broke. We were traveling maybe 50 mph. He swerved around a bit pulling onto shoulder. The front tire and wheel was folded out horizontally. You might say that's not surprising for a car that old, but it was only 4 years old when it happened.

but, broken, it just felt bouncy, it didn't drop your butt on the road at speed, no?

If it had been backbone or downtube the results may have been different. If I had been accelerating hard out of a tight corner they almost certainly would have. All materials can break. With little or no warning.

And let us not forget that steel is proven to be the weakest of frame materials.

http://sheldonbrown.com/rinard/EFBe/frame_fatigue_test.htm

And let us not forget that steel is proven to be the weakest of frame materials.

http://sheldonbrown.com/rinard/EFBe/frame_fatigue_test.htm

........................................Oh please.http://www.runemasterstudios.com/graemlins/images/laughing.gif

........................................Oh please.http://www.runemasterstudios.com/graemlins/images/laughing.gif

Hold on. The closest thing to an empirical test that anyone has ever done, and published. Carbon was in its infancy. The people doing the test were expecting steel to do well. And steel completely shat the bed. As in not even close. You can feel free to dismiss it. I tend to think that it shows that steel is not the ideal material for lightweight, racing bikes. But hey, until someone else does another empiricalish test, (maybe in another 15 years) it's the best we got...

..........................here is one:

http://www.bikeforums.net/showthread.php/861812-Frame-material?highlight=frame+material

Read it, and you can pretend that every other posting is me arguing with you, if you want to.



Let's cut to the end of the chase: someone who gives a **** can make a pretty good, durable bike
out of any of the commonly used frame materials. Conversely, someone who does not give a ****
can turn out one that will fail, and even some of the better ones can fail in the right circumstances.


Don't you think that if the answer were that simple it would be more widely publicized ?

I smell a conspiracy that leads directly back to Andrew Carnegie and the Illuminati.:o

METALLURGY FOR CYCLISTS (http://www.ibiscycles.com/support/technical_articles/metallurgy_for_cyclists/)

Thing about carbon fiber bikes, the pros only use them for. maybe, a couple weeks, then replace them.

like aircraft flight logs document hours of service ,the the replacements all have scheduled time to replace them..

If it had been backbone or downtube the results may have been different. If I had been accelerating hard out of a tight corner they almost certainly would have. All materials can break. With little or no warning.

And let us not forget that steel is proven to be the weakest of frame materials.

http://sheldonbrown.com/rinard/EFBe/frame_fatigue_test.htm

Can we please get past this discredited test (http://www.tomsarazac.com/tom/opinions/frame-test.html) and get to the crux of the failure mode of CFRP structures?

Here are post-mortem photographs of the CFRP vertical stabilizer attachment lugs of the scarebus, er... Airbus 300 equipment used for American Airlines Flight 587. The vertical stabilizer spar attachment lugs, which separated from the airframe in flight resulting in the loss of 260 passengers and crew members and 5 people on the ground, simply snapped because the aerodynamic loading on the rudder exceeded the design stress of the spar to lug attachment. Because of the low elongation of CFRP, the failure mode of CFRP structures is sudden and catastrophic. Would a Boeing airframe billet aluminum vertical stabilizer spar to airframe attachment have failed under similar loading? It might have deformed (bent), but it is highly unlikely that it would have failed so catastrophically.

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/CFRP%20Failures/AA587CFRPVertStabLugFail.jpg

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/CFRP%20Failures/AA587CFRPVertStabLugFail02.jpg

Can we please get past this discredited test (http://www.tomsarazac.com/tom/opinions/frame-test.html) and get to the crux of the failure mode of CFRP structures?

Here are post-mortem photographs of the CFRP vertical stabilizer attachment lugs of the scarebus, er... Airbus 300 equipment used for American Airlines Flight 587. The vertical stabilizer spar attachment lugs, which separated from the airframe in flight resulting in the loss of 260 passengers and crew members and 5 people on the ground, simply snapped because the aerodynamic loading on the rudder exceeded the design stress of the spar to lug attachment. Because of the low elongation of CFRP, the failure mode of CFRP structures is sudden and catastrophic. Would a Boeing airframe billet aluminum vertical stabilizer spar to airframe attachment have failed under similar loading? It might have deformed (bent), but it is highly unlikely that it would have failed so catastrophically.


Holy shnikes, now you are an imaginary expert in airframe engineering. And you quote an article that didn't even bother to do a real experiment, but just spouted a bunch of nonsense and offered that as proof, that the German test, was actually proof that the frames that failed, were in reality stronger. For the record, I ride an aluminum frame. I think steel is capable of being formed into perfectly fine frames, although at a significant weight disadvantage for the same strength to CF and Al. But the imaginary, only on the interwebs nonsense, that posits that steel is in some way stronger than the other common materials for building bikes, is flat out laughable.

Holy shnikes, now you are an imaginary expert in airframe engineering. And you quote an article that didn't even bother to do a real experiment, but just spouted a bunch of nonsense and offered that as proof, that the German test, was actually proof that the frames that failed, were in reality stronger. For the record, I ride an aluminum frame. I think steel is capable of being formed into perfectly fine frames, although at a significant weight disadvantage for the same strength to CF and Al. But the imaginary, only on the interwebs nonsense, that posits that steel is in some way stronger than the other common materials for building bikes, is flat out laughable.

Actually, most of the more recently popular bicycle frame materials
came to us direct from the air and space industries.(Reynolds 531,
Titanium tubing, most of the early composite research, etc.)

For obvious reasons, they, too, are very interested in strength to
weight ratios and avoidance of catastrophic failures. They also have
considerably more cash to throw around in terms of systematic testing
and design of these materials, as well as greater resources in logging
and investigating failures.

One begins to suspect that your interest here is less benign than I first assumed.

If you really are interested in the materials science involved in this, I'd suggest
that you embrace a willingness to go beyond the bicycle only literature, amigo.


Edit: OK, in the interests of understanding, I just pulled up some of your recent posts.
You're a ****ing Strava roadie, for god's sake.....can you say'"agenda?":roflmao2:

Actually, most of the more recently popular bicycle frame materials
came to us direct from the air and space industries.(Reynolds 531,
Titanium tubing, most of the early composite research, etc.)



Don't forget 6061 aluminum, which is used extensively in the aircraft industry. :)

Actually, most of the more recently popular bicycle frame materials
came to us direct from the air and space industries.(Reynolds 531,
Titanium tubing, most of the early composite research, etc.)

For obvious reasons, they, too, are very interested in strength to
weight ratios and avoidance of catastrophic failures. They also have
considerably more cash to throw around in terms of systematic testing
and design of these materials, as well as greater resources in logging
and investigating failures.

One begins to suspect that your interest here is less benign than I first assumed.

If you really are interested in the materials science involved in this, I'd suggest
that you embrace a willingness to go beyond the bicycle only literature, amigo.


Edit: OK, in the interests of understanding, I just pulled up some of your recent posts.
You're a ****ing Strava roadie, for god's sake.....can you say'"agenda?":roflmao2:
A strava roadie on a 10 ear old Easton Al frame. And of course, the aerospace industry has been pretty CF oriented for a whole now. But I'm the crazy man with an agenda...Suuuuuuuure.