Friday, August 10, 2018

More Warnings About Carbon Fiber Bikes

I recently came across an article in Outside online that rings more alarm bells about carbon fiber bikes and components - though it's all well-trodden ground on this blog. There's not much in the article that hasn't been raised plenty of times already in The Retrogrouch - it's just that I don't often see these concerns raised by more mainstream publications.

One of the more interesting things the article talks about is how, if someone has a carbon fiber bike and it fails, it can be difficult to get anyone to take responsibility. For example, a person may own a CF bike made by a huge well-known Taiwanese manufacturer (they're almost all made in either Taiwan or China) - but the bikes are actually distributed by another huge company (probably an independent subsidiary with the same name) based in the U.S. Now, let's say that customer's bike fails and they get injured. They sue the manufacturer in Taiwan - who claims that they can't be sued because they don't actually do business in the U.S. - if you want to sue someone, sue the U.S.-based distributing company. The customer tries that, but the U.S. company claims they can't be sued because they aren't the ones who actually made the bike. The difficulties can keep a consumer tied up in courts for a long time. Isn't that nice? According to the article, recent court decisions may make it a little easier for such lawsuits to move forward - but things are still in a state of flux.

Other more well-trodden points look at how manufacturing defects that can lead to failure may be hidden and very difficult to detect. Or how damage can come from an accident of some kind - but be unseen until it eventually fails - maybe long after the accident is long forgotten. Both are points I've raised plenty here over the years. If the manufacturer can point to an installation or maintenance issue or an accident (no matter how minor/insignificant it may have been) as the cause of failure, then there is no warranty coverage when the bike or component breaks.

Something I found odd in the article, though, was that it opened with a story that I'd hardly consider an exemplary case. Here's the opening:

Janet Kowal had a personal connection to the Register's Annual Great Bicycle Ride Across Iowa (RAGBRAI). Even though she’s now living outside Chicago, working for the Village of Burr Ridge town hall, Kowal has Iowa in her blood. The 2013 route would take her through her hometown of Des Moines and skirt the University of Iowa, where she graduated in 1987. Kowal bought a new-to-her 2007 Giant OCR C1 road bike for the event and, to be cautious, took it to her local bike shop for a full-service tune-up.

Not long into the ride, however, Kowal’s bike shattered beneath her. For no apparent reason—she’d neither hit an obstacle nor encountered a pothole—the front fork snapped in half as if it had exploded from within. Kowal was sent crashing into the pavement, helmet first. She fractured her spine and clavicle, suffered a concussion, and tore ligaments in her left thumb.

Okay - anybody else think it's weird that they focused on a 2013 incident involving a used bike that was already 5 or 6 years old when the woman purchased it? If the main point is that it really isn't a good idea to buy used carbon fiber bikes (or components), then point taken. But it seems to me that the intended point is broader than that. I mean, pursuing compensation when a used bike fails is complicated regardless of what material the bike is made from. Manufacturer's warranties almost never cover anyone beyond the original owner - and (as already mentioned) they are almost never held responsible if they can make the case that an accident or some user-error caused the failure.

One never knows what kind of accidents, abuse, or neglect a bike may have suffered under a previous owner, and with carbon fiber, the damage may be almost impossible to detect. At least with a steel bike, such problems can often be seen if someone knows what to look for. Steel wears its damage on its sleeve. The fork may be bent. There may be a ripple or a small crack developing somewhere. Paint could be bubbled or cracked.

A head-on collision will often leave tell-tale signs on a steel bike that even a new coat of paint may not hide. That little ripple behind the head tube is one. A bent fork is another. It's pretty subtle, but that fork on the right is almost certainly damaged.
I have no doubt that carbon fiber bikes today are better than those made ten year ago - and further improvements will be made. But it's all still developing technology. It begs the question how long will such bikes last? I have no qualms about riding a 40 or 50 year old steel bike. But where will today's carbon bikes be in 50 years?

Anyhow - it's worth clicking on over to Outside to read the article, but if you've been reading this blog for a while, there probably won't be much there to surprise you.


  1. Interesting they had to look back five years to find an article-worthy carbon failure.

    1. The point of that article, as I understand it, is that carbon is initially quite strong as a bike material, but it degrades more quickly than any other frame type, and when it fails, it does so catastrophically and without warning. There's also the challenge of finding redress when the manufacturers are complicated corporate conglomerates that do everything in their power to disclaim liability for failures of their frames.

  2. One quote from the Outside article struck me in particular:
    `In a widely reported crash in February involving a Trek Domane carbon-fiber frame that split in half, Shriver says Trek’s engineering department sent him a link to an article, asking if the cause could be a manufacturing defect. “I looked into it, and it turns out a guy fell on the frame during the crash,” Shriver says. “That’s the kind of impact that could cause any material to break.” `
    I beg to differ, Mr. Shriver. If I fell on my steel-framed bike in a crash, I would be broken; my bike, however, would be fine.

    I recently rode in the Pan-MAss Challenge this August, and one observation that I had while waiting to board the ferry home seems relevant here. I was one of ~250 cyclists and bikes waiting for the 2 PM ferry home. I was in a gazebo overlooking the loading dock and saw everyone file past towards the boat. I think I saw 3 bikes (I didn't look at every single one of them, mind you) that had their frame tubes wrapped in the foam insulation tubes that you'd use to insulate the water pipes in your home. Those bikes were invariably the carbon-fiber type. I don't ever want to ride a bike that is so fragile that you need to guard it against incidental bumps (let alone, the constant fear of riding a bike that could fall apart beneath you at speed).

  3. With carbon fibre, the bike companies have the perfect consumer product. It's very expensive, has a relatively short shelf life and must be bought anew at regular intervals.

    Incidentally I've personally seen steel forks bent worse than the ones in the picture that were bent back into shape and ridden for years after. I'm not saying that's a good thing to do but it does show the resilience of steel.

    1. If the life is short, that's poor design or manufacturing. There's no physical reason a carbon bike can't be made that would last at least as long as a steel bike. I'll admit I don't know what the engineering cost is, but one could always just overdesign it. Carbon fiber composites are much lighter than steel, so more can be used, reducing fatigue. I'm sure detail design is important, too. I think if I was in charge at a major manufacturer of carbon fiber bikes, I'd have someone do experiments subjecting samples to millions of stress cycles, before selling anything. That's not a small order, but being impaled on broken parts isn't a small pain.
      I suspect that if one were to do a thorough search of aerospace literature, one could find most of the techniques required to make a damage-tolerant, long lived bike frame.

  4. I don't get why they can't just stick a layer of material over the structural carbon that holds fractured parts together and contains flying shards. Some sort of fabric. It would add few grams and the carbon would still fail but the bike or component would "merely" go from rigid to floppy. Surely this scenario must be easier to handle by the rider than total disintegration.

    1. Something like Kevlar might be good for this. I'm not sure how much you'd need to make failures more benign. I'm sure it would add significant weight, but might still be lighter than some other materials. You can also get carbon/kevlar hybrid materials which might be useful for limiting crack formation or something. Seems to me that, if you were thorough and careful, you could add the Kevlar yourself, but it would make the bike look ugly! I suspect that there is some other application where this sort of thing has been worked out. Don't they use carbon fiber cages to protect race car drivers now?

  5. Also the industry has clearly been underinvesting in fault detection systems that attach to your bike, such as sensor strips that run the length of the structural parts being monitored, via app (of course, what bloody else). No, it's more important for the rider to measure every aspect of their pathetic effort.

  6. Against my better judgement I bought a carbon fibre bike as a quick replacement for a titanium bike I lost (it's a long story). It rides beautifully. But I had a couple of minor falls on it. I believe these would have done nothing more than scratched the paint on a steel or titanium bike. There was no visible external damage but, valuing my life, I completely disassembled the bike and had the frame and fork examined by experts who deal with carbon fibre in planes, yachts, bikes, and static structures. This cost around $400. The experts x-rayed the frame and forks. They said the steerer was damaged and should be replaced. Looking closely at the steerer I could see exactly ... nothing. The experts had no connection to my bike shop or the manufacturer; they had nothing to gain by deceiving me.

    Every time I unpack the bike with its new carbon fork from its travel box, or off the roof racks of my car, or am tempted to let it rip down a hill, or am just doodling along on a flat road to the cafe, I tell myself the odds of it unexpectedly falling apart beneath me are not high. But the thought is always there in my mind. That uncertainty is not worth either the manufacturer's claimed "extra drive train efficiency" or the 400–1000 gm I've "saved" over a titanium or steel frame and fork.

    I know there're probably millions of carbon fibre bikes rolling around which will never fail. I know that both titanium and steel frames can be badly built, can crack, or fail in some way. But you usually get some visible warning that regular maintenance will pick up. And steel, in particular, can take a lot of damage before it fails. The fragility of carbon fibre, the invisibility of damage, the propensity for sudden and catastrophic failure, makes it, IMO, about the worst material from which to make a bike that's not used for racing (and therefore presumably subject to regular rigorous examination and replacement). I rue my impatience, and wish I had instead invested my time and money in a custom steel or titanium bike. Or even one of these off the shelf.

    (Incidentally, it took around 6 weeks to replace the fork, since it had to be imported to where I live. Why wouldn't a major bike brand keep replacement parts in country or have a quicker supply system?)

    1. IF it makes you feel better, I have met people who've had crashes from catastrophic failure of aluminum bike parts. I can definitely remember one guy who had the handlbars break, and I think I remember another who busted a crank. John Allen has identified some types of stems that fail:

      I expect that some technique has been developed to reliably detect damage in composite structures. Maybe even an inexpensive one. Perhaps many strands of fine magnet wire or optical fibers could be laid up in the frame. Then, if a crack formed, the network of wires would no longer conduct electricity or the optical fiber would no longer carry light. Some aerobatic aircraft are made of sealed steel tubing. The tubing is pressurized with air, and a pressure gauge is attached where the pilot can see it. If the pressure goes down, there is a crack. In lieu of a gauge, perhaps a little mercaptan or something similar could be put in the frame before it's sealed.

  7. No. the catastrophic failure of some aluminium parts does not make me feel better! I've seen some shattered cranks—I suspect they'd first been involved in falls or collisions—but never handlebars. And I've heard of broken handlebars, but in 45+ years of riding and building bikes for myself and others, I've never actually seen any break. I hope not to. The worst I've seen or experienced are rims cracking, either because of poor maintenance, building or manufacturing—mostly because people don't check them for brake wear.

    Over-engineering, embedding magnetic fibres, and sealing tubes all sound like possible solutions but none of these, unfortunately, will address the other glaring issue about carbon bikes: to my knowledge, they cannot be recycled. Incidentally, I believe the fatigue life of properly made carbon is very high; it's susceptibility to impact damage is poor. Perhaps an engineer could clarify?