This thread reminds me why I don't believe the internets

Alright I stand corrected on resins, don't know much about them. Steel, concrete and brick are more my thing

I would assume or expect that bicycle manufacturing engineers conduct testing on the lifespan of CFRP over time, under UV exposure etc., and build in necessary tolerances accordingly.

It is possible that carbon fiber bicycles used to be designed with higher tolerances thus safer. It is also possible that some manufacturers are skirting the limits of what is allowable. On the other hand, it is just as feasible that advances have been made in the resins and layups of carbon fibers, or just in the design of the frames themselves, such as to reduce the weight without compromising strength or durability.

I know BMC for example started implementing carbon nanotubes (little strands of carbon atoms just a couple of nanometers thick), and infused them into the resin. I can imagine this would at least partially mitigate any failure or propagation of cracks throughout the resin for example. So there might be other reasons than just "designing them less safe" that can reduce weight.

I think there is no reason for pushing people away from carbon fiber composite bicycles, and the "evidence" I have seen on the failures is anecdotal at best. Googling pictures of broken carbon fiber bicycles is no scientific evidence of a widespread problem. I just googled "aluminum frame failure" and came up with similar photos on aluminum frames.

I would love to see a proper scientific study done that tests a large number of frames after 1, 5, 10 years into their lifespan, on impact, fatigue, etc. Until I see a study like that proving that carbon fiber is unsafe after a number of years, or a statistic analysis of CFRP failure related injuries, I don't see any reason to spread fear about it.

What misinformation? I showed you the picture of that frame where the head tube separated from the rest of the frame for no reason whatsoever. It occurred at the south side of the bicycle path to the Golden Gate bridge where you turn off of the bike lane on the road onto the bike path. Since it is steep on the road and there is a slight lift on the path everyone slows to 5 mph or so at that point.

Or do you think that I am spreading misinformation about the man to whom this failure happened. Who has had half a dozen surgeries to his hand and the small finger is still sticking straight out and will not fold out of the way like most people's hands? Think of trying even to write your own name.

What is odd is that people who own and ride carbon fiber bicycles, especially the higher end, are the greatest deniers of any negative aspects of the material. People who want to pretend to be racers so they buy extremely expensive frame/fork combos that were designed for racers. Do you figure that you are Chris Froome in another body? Do you walk around trying to emulate a British accent?

I see no reason to push people away from CF frames and forks that are properly constructed but people aren't buying an 18 lb carbon fiber bike. Carbon nanotubes still have to be held together with resin. I think that it could give a longer lifespan to CF in a best case scenario but most of this isn't engineering - it is manufacturers guessing at things. Remember that these things are mostly made in China and they have more than enough work for the best engineers in fields other than bicycle design.

I did contact some CF engineers and they did convince me that you CAN built a safe and light CF bike. But all it takes is the slightest problem with the layup and it can break at that point. And the construction technique for building these things inside of molds with inflatable inner liners sure doesn't seem that foolproof to me.

Perhaps graphene offers more strength to light bikes but I really haven't been able to find any real information on it except the raving from dopes that don't know anything about it. But I think that layering graphene by molecular attachments would be pretty damned expensive. A sheet of graphene is only one molecule thick so you would have to layer these sheets with cross linking the molecular structure. The problem and advantage of this is that there would be pretty much two molecule thick sheets separated by cross bonding of carbon molecules here and there. This would separate the sheets with open space but I imagine that could give more strength than the two sheets laid one upon the other and covered in resin to hold the assembly together.

One of the things I haven't been able to discover is how large they have been able to make the sheets since this would be important to mechanical construction techniques.

A Google search returns more than 10 pages of seatposts up to $50. The majority of them are aluminum. I'm not sure I would buy a carbon post for less than $50 for a heavy rider to begin with...

...This kind of says why. If you damaged a post because of your weight, it would be wise not to go with a post that is more delicate, especially a cheap delicate post. I have one bike with a carbon post but it's a higher end post and I ride really light in the saddle. I have bent a post in the distant past but that was before I learn how to ride with more finesse and less hamhandedness.

Just about any of the alloy seat posts in a Google search will work and work well.

I googled broken aluminum frames as well and noticed that all of them were off-road bikes and I suppose we have to give them a learning curve. You had to be a little careful because some of those broken frames appeared to have been repaired via heliarc so it is unclear what actually happened.

The Redline cyclocross bike that had the headtube broken off hit pretty close to home since I have a version - the Conquest. Upon close inspection though it looks like a manufacturing error. The downtube broke at the weld and the toptube couldn't bear the stress. Remember that cyclocross bikes absorb all of the stresses of an MTB and are as light as a road bike. So you have to be ultra-careful with quality control.

And the steel bike failures did not appear to be catastrophic - bent downtubes from collisions with cars and the like. I am sure that there have been failures with steel frames that caused crashes and injuries but I haven't seen any and as you say, googling frame failures isn't a good source of information without full knowledge of the circumstances. I have seen pictures of broken chain stays, broken seat tubes at the bottom bracket and I personally had a seat stay break on a Peugeot el-cheapo producto. But all of these steel bike failures allowed careful return to home.

What we can say is that the drive for lighter and ever lighter carbon frames is putting a greater likelihood of catastrophic failure.

Hold on there just a second. First, you are unlikely to find too many pictures of broken steel frames because there are fewer steel frames out there being ridden. The vast majority of bicycles, especially modern ones, are aluminum with carbon coming up fast. There are a few pictures of broken steel frames around like this one and this one and this one to name a few. I doubt any of them were "rideable" afterwards. I also doubt that the failure was slow as well. I've personally broken steel and aluminum frames (two each). The steel frames snapped audibly and were unrideable mostly because the axle snapped as well. Aluminum failed more gently and over a longer time frame. The aluminum bike creaked and groaned for a long time before it failed. I actually rode it for several weeks before I found out what the creaking was from.

Aluminum and carbon don't "shatter like glass" any more than steel does. Steel, being rigid is much more likely to shear suddenly than a soft material like aluminum...which tears...and carbon which is a fabric with alternating layers of fiber running in different directions.

Quite to the contrary - there are FAR more steel bikes in use than any other material by a wide margin. Do you think people are going to commute on a Trek Madone? Hell, try and buy a Schwinn Voyager off of Ebay. You can pick them up for a song and dance. And they are a hell of a lot less likely to get stolen or the U-lock sawed off. The bike messengers I've seen in San Francisco are riding steel single speeds. The rental bikes are all aluminum built so heavy that they might has well be steel.

You show one photo with the guy saying that the Specialized (which at the time was a cheapo brand)broke in the center of the downtube away from the lug when you could plainly see it broke at the lug of the steering tube. Then you can also see that the failed "unknown make" bike had been a long time out in the rain and with that cheap headset had allowed water into the steering tube where it rusted the lug/steering tube out. And why don't you see any braze in the joint? Cheaply built bikes of any material will have a short lifetime and that bike judging from the components was both cheap and I would guess 35 years old and not 25 as they guess. If you shatter a CF bike you generally are carried to the hospital. That broken 583 frame probably would not even dump you and could be ridden albeit carefully home.

If you've broken FOUR metal frames you had better tell us the circumstances and the makes and models of each before you imply for one second that CF is in any way safer.

“Anyone in a team who’s being honest with you will tell you how frequently their bikes are breaking; everybody knows,” said Mark Greve, a physician and assistant professor of sports medicine at Brown University who studied injuries to 3,500 competitive cyclists. “Few people in the public appreciate how many bikes a pro team will go through in a season, because they break"

"Doug Perovic, a professor of materials science and engineering at the University of Toronto, said carbon fibre was a bit like a diamond: strong while not being particularly tough."

By all means - after you've broken four metal frames be sure and continue riding a carbon fiber bike. Might I suggest a Ghost? You will soon have a lot in common.

Sure there are a lot of old steel bikes still floating around out there and a certain percentage of bikes sold each year are steel but nonsteel bikes have made up a huge percentage of the market since the early to mid-90s. Over 25 years, the number of nonsteel bikes has grown larger than the number of steel bikes.

People tend to ride new bikes more than old bikes and the part of the market that is dominated steel bikes...the BigBox Store bike...don't get ridden as much when new as higher quality bikes. Since they get ridden more, they tend to wear out, get damaged and break. It happened even during the age of mostly steel bikes. The material in highest use will tend to be the material that has the highest failure rate.

As to your other points, we aren't discussing theft or weight.

Specialized has never been a "cheapo brand". Nor did the frame break the lug. It broke below the lug.

As for the other two breaks, lugs are supposed to be stronger and resist breaking. That lug obviously failed. Even if the lug broke because of corrosion, that points out one of the problems with steel bikes...they are prone to corrosion problems that nonsteel materials don't experience.

The broken seat tube is no more ridable than any broken aluminum or carbon frame with a break in the same area would be. Frankly, I wouldn't ride any of them.

My point, which you missed entirely is that broken frames of any material are just as likely to be unrideable as any other material.

I'm not implying that carbon fiber is safer than other materials. I'm saying that no material is any better at resisting breakage than any other. I'm also saying that the failure modes of carbon and aluminum aren't like those of glass. That old horse is trotted out anytime a new material comes along that isn't steel. In my experience, failure of aluminum frames and parts isn't sudden and catastrophic. It's a long process that is accompanied by a lot of warning.

Steel, on the other hand, is sudden and catastrophic and, more importantly, it fails without warning. It doesn't bend gently. It doesn't creak and groan before it fails. It just shears kind of like people think aluminum breaks.

As for carbon fiber, I haven't experienced a carbon failure yet. I've seen some failures and they all seem to be rather slow events as well. I only have a couple of carbon parts...forks actually...and haven't had any problems with them including a fork that is about 10 years old and has 17,000+ miles on it.

I don't ride carbon. It just hasn't appealed to me. I'm just saying that it doesn't break like you think it does.

since cyclintom is here, I have to say...


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Carbon fiber makes up only a "huge percentage" of the top end market. And that isn't large. And it's mostly a US market as well. Where in the world can people pay $10,000 for a bicycle?

You're discussing how common steel bikes are. And they are still very common and are coming back again because they are cheap and now carbon fiber is pricing itself out of the market. Unless you count a Nashbar frame that will flex so much that your heel hits the chainstay.

Specialized was middle range for the largest part of their history. Bridgestone was a better bike and there isn't a lot you could say about that line of bikes. When I say the Specialized broke at the lug why do you claim I said the lug broke? Do you understand what butting of steel tubing is and why bikes have to be built with the proper tube set for a particular size bike? That bike had a tube set for a larger bike and broke because at that point the tubing was probably .020 thinner than the center portion. It could lever against the lug because that "never been a cheapo brand" was cutting corners on tube sets. So because of the butted sections sticking out of the lugs it could flex and break there. And as you could see the OTHER failure was also at the seat lug. Some "never been a cheapo brand".

I'll tell you what - YOU ride a carbon bike with a broken seat tube and I'll ride a steel bike in the same condition and let's see who walks home.

I have seen what fails and clearly you haven't. I posted pictures of sudden failures of CF and I have never in 40 years seen a steel frame do that - even cheap steel bikes. I didn't even know the chain stay on my Peugeot was broken until I put it on the workstand after a ride.

Busted Carbon

Half of these failures are from crashes of one sort or another. However - the other half occurred when the rider was riding along. A STEEL bike of this quality would not fail from even most of the crashes.

We obviously have far different views about frame materials. I am now 73 years old and have seen a lot of failures. The largest amount of these were rider error such as me using egg-beater pedals and spinning so fast down a descent that my foot popped out of the pedals and flew into the front wheel spokes - ouchy. And in the same stretch on a different ride a guy that was always slow decided to race down through a twisting section went off the road an into a barbed wire fence. I still remember trying to lift the barbs off of him in a manner to cause the least amount of damage.

My only steel bike failure was when I was first learning to ride (again of course) and it was a slow ride with a slow group.

But I've had three carbon forks fail. The first was an IRD that was manufacturing error of the first water. The second was a vertical crack in the fork leg that allowed the fork to flex and the wheel to touch the leg and threw me off into a pile of dead leaves that gave me not damage at all. I did ride that one back home VERY carefully. But I should have taken a hint at that because 5 feet further from that pile of dead leaves was a stone culvert. The thirst was occurred when I was descending a road at about 40 mph and hit a bump in the road. Not a pot hole or a grating or anything a bump. I went back later to find it and it looked like perfectly smooth road to me. In any case this did the same thing to Colnago's top of the line Flash fork. A vertical fracture from the left dropout for only about the length of the molded in part of the drop out. This allowed the wheel to twist very slightly causing me to drift off the road into the gravel. I was applying what little brakes I could and using my shoulder against the cliff face to slow. Just as I was about to regain control there was another stone culvert big enough for the bike to fall into. As luck would have it my head was clear of the culvert to the entire force of the collision was absorbed by my body without any further head injuries.

So I am not warning people because I've had bad luck. I know how to crash and since I ride off-road too I crash quite a bit. I'm warning people because almost no one knows how to crash with a surprise failure. And all it takes is one of these to change your life forever.

If it wasn't for my cop friend who wouldn't give up until he found me the proper treatment I would be dead now. And that picture that I posted of the C40 that the head tube had broken off of with no warning was that of that cop who now has his little finger paralyzed. The world is always poorer with one less cyclist. Even some stubborn old argumentative one like me.

I didn't say that carbon fiber makes up a "huge percentage" of the market. I said "The vast majority of bicycles, especially modern ones, are aluminum with carbon coming up fast." Aluminum bikes have outsold the steel market...not including BigBoxStores and youth bikes...for the better part of 2 decades now. People are more like to have had experience riding a good quality aluminum bike then they are to have ridden a quality steel bike.

High quality steel bikes aren't all that common and even the low end HelMart bikes are edging more towards aluminum than steel. As for steel "coming back", there are a few but, by and large, aluminum has most of the market and carbon is pushing aluminum out at a fairly good pace. Not all carbon bikes cost $10,000. Specialized sells a hardtail carbon bike for $2500 which is not a bad price for a middle of the range mountain bike. They also sell a $1600 carbon road bike which is definitely within the middle of the price range for a quality bike, especially considering that the lowest priced road bike in their line is $750.

Any steel resurgence is limited to retrogrouches...young and old. The rest of the world has moved on.

No, Specialized has not been "middle range" for most of their history. They were, and are, cutting edge. The Stumpjumper was the first production mountain bike in 1983. It was a high end bike that was rather expensive for the day and quite radical as well. Their mountain bikes were ridden to many World Championships and could be purchased by us regular joes. Their bikes have always been good quality. And, considering that they have seemed to have outlasted Bridgestone by about 25 years, they have been doing something that is successful. Or, maybe, their customers are just stupid

Look at the picture again. There is a stub of downtube that is painted white sticking out of the lug on the frame. That means that the tube broke outside of the lug. As to the tube being butted, I don't know if it was or not. That said, even if it were butted, the thicker end of the butt is at the lug so that it can take the heat of brazing without the tubing being damaged. The thinner part of the tube is further away from the lug than the stub shown in the picture.

The Reynolds frame with the broken seattube broke above the lug as well. That is the thickest part of the tubing set.

But, more to the point, you have said that steel frames don't break like that. Obviously they do. I've seen other instances as well. My steel frames have broken suddenly and without warning.

Neither would be something that I would ride. Both are unsafe and to continue riding one would be to invite disaster.

How do you know I've never seen a frame failure? I've seen lots of them. I work at a bike co-op and have seen bikes that have been run into garages, been hit by cars, been dropped off cars and just plain failed. Overall, frame failures are fairly rare but they can happen to any material. Carbon and aluminum don't have a lock on failure at joints either...as can be seen in the first picture I linked to.

Yes, we do.

And I've had steel frames and a fork fail on me. I haven't had that happen with carbon forks nor with mostly aluminum suspension forks. Nor, for that matter, have I had that many frame failures ...even when considering that I've experienced 4 of them. That's 4 failures out of 38 bikes. Two of the failures were due to poor materials...my first mountain bike, and a very early model at that, that was under built for the application and had a history of failure which included that single fork and one mountain bike that was made of a material that couldn't stand up to the rigors of the sport. One of the failures was because I was using a seatpost with too much setback that stressed the seattube...which is my fault. And I had one bike fail because I was using it as a mountain bike when it really wasn't designed for that.

I haven't experience any frame problems with the other 34 bikes and I'm not too worried about the quality of the 9 I currently have. I ride them and they do the job. Most of them are going to do a better job than my first mountain bike.

And I'm here to tell people that it's not something to lose a lot of sleep over. Yes, a frame can break. It's just unlikely. Even with all the experience I've had with broken frames...which is more than most people experience...I'm not all that concerned about a frame breaking no matter what the material used in construction.

I don't currently own a carbon bike. I don't know if I'll ever own a carbon bike. I've held off carbon for the same reason I held off dual suspension bikes. I was waiting until the technology is a bit older and better developed. It's there now and I wouldn't have any qualms about owning one just as I don't have qualms about the carbon forks on the bikes I own.

Can we skip all this trivia and get to the core of it: are carbon posts less likely to get stuck?

Asking for a friend.

depends on the frame.... 7000 series aluminum has a % of Zinc in it..