I've snapped steel rigid forks back in the 90s
Google almost any brand of frame or form snapped and you will find one
These will have been tested, I guess there will be a regime of batch testing required by planet X insurers.
There’s a guy who has done a few videos with carbon bike repair where they cut open old frames and forks. I remember they cut open a Chinese trifox frame and the expert thought that there wasn’t enough carbon in the fork crown
doesn’t fill you with confidence, but then again there must be hundreds of thousands of carbon forks out there, and these incidents are incredibly rare
as I recall, canyon shove their carbon parts through an X-ray machine as part of the actual process. I’m not sure a chap in a factory looking for external signs of defects in the carbon would be quite as effective
Metal bike parts, frames or forks don't really snap, they crack slowly then give way fast at the end, or they fold. (edit, I suppose a really bad weld could give a 'snap' effect as it simply pulls away)
I've raked out or cracked 3 steel forks over the years and all were rideable to some extent after the damage, none cause a serious crash. The cracked forks were ridden for a while before spotting them, had me thinking I had a slow flat for 100 miles or so before I started looking at the bar and fork and found a blade cracking away from the crown. Totally different type of failure and reasons for it to what can happen with carbon I know, the point is about how things fail and the likelihood of visible warning signs. It's common to think carbon doesn't fatigue like metals do but there can be deterioration internally that has the same basic effect.
There's a reason bike owner manuals mention inspecting parts from time to time, it's not a bad thing to have a reminder (like my bars were - must retape another bike soon to check the bars on that)
as I recall, canyon shove their carbon parts through an X-ray machine as part of the actual process. I’m not sure a chap in a factory looking for external signs of defects in the carbon would be quite as effective
There was a good challenge to the efficacy of xray and ultrasound use like that a while back, about ability to interpret the signal or read outs and how it was pointless unless real time was spent on the parts, time that simply wasn't in the usual production QC process. Was interesting but I can't remember whose it was.
There’s a bit in one of the Cy/Cotic mech engineering lectures where he talks about the CEN test that includes a ‘pull apart’ component and he asks the students why that is, someone says the obvious answer “landing a jump flat”, so he explains the G-force required to minic the CEN test, it’s MASSIVE, basically impossible in the real world, and annoyingly the driver behind larger top tubes.
Yeah, I saw that lecture.
My point was that it didn't really tally with this bit, in my mind:
The keen cyclist, who was working as a junior doctor at Raigmore Hospital, was only travelling at around 15mph before the bike collapsed beneath him, throwing him to the ground.
It sounded like he was just riding along and then it suddenly collapsed. If that were the case I would expect the wheel to travel forward unless something was hit with enough force to stop the wheel. Or for him to have hit the brakes causing the fork to snap.
Reading it again though, I saw this part:
‘In the course of descending the grass slope at a speed of about 25 km per hour (15.5 mph), which is terrain and a speed the claimant will say ought to have been well within the capabilities of the bike, the carbon fibre front forks suddenly and without warning sheared in two at the base of the steerer tube, causing the front wheel of the bike to collapse rearwards.
Makes a bit more sense. A grass slopes could have plenty small divots to grab the wheel.
Either way, should have been well within the capabilities of any bike, assuming it wasn't a grassy slope with 2 ft deep craters.
Should carbon fibre have a different type of material interwoven that doesn't just snap if the carbon breaks? Maybe something like kevlar?
I'm no materials engineer but I'd have thought that it wouldn't add a lot of weight but I'm not sure if it would work, just a thought.
Edit: apparently so
Shouldn’t all bikes with this fork (or close variants) be recalled? That’s what would happen in the automotive industry. I remember previous failures with I think, some Kinesis? forks where details were widely published in the press - after a death whilst just riding along. And… didn’t Specialized delay one of their road models and recall any that had already gone out? Life is dangerous enough without commercial interests taking front seat.
"It’s common to think carbon doesn’t fatigue like metals do but there can be deterioration internally that has the same basic effect"
I think that was one of the reasons cited for the failiure of that Oceangate titan submersible and why experienced sub engineers had always said it wasn't a good material to make hulls from. Certainly in the sail racing. world there are many many examples of carbon spars and even hulls failing under repeated load.
However as this tragic incident happened on a brand new bike in benign conditions then clearly there must have been a construction fault or corner cut in manufacturing. Maybe its easier for this to happen when making large volumes of carbon parts versus large volumes of alloy or steel parts?
We've three full carbon forks, one a Ritchey, one a Trek and one a Ridley 😬
No issues to date 🤞
No carbon fibre alone is sufficient. Glass is added to reduce cost. Kevlar can help with flexibility and impact resistance if I remember. Polypropylene can be used to hold the structure together during layup but that might be particular niche.
They are composites so you need to consider the resin also. The biggest challenge i'm aware of is bubbles in the liquid during manufacture. That's why vacuum layup is generally better. You can compensate for some bubbles by adding more material but only to a point.
In the fatigue testing I do we can see metal fail before composite, it's normally a defect causing localised stress build up. Most common is a burr or lump on something that is clamped. This particular case sounds like an impact failure rather than a fatigue though.
Shouldn’t all bikes with this fork (or close variants) be recalled?
I think this would make a fascinating (if brave!) topic for a STW article. Especially seeing the number of reader/subscriber/forum member riding around with this exact fork must be pretty high given the popularity of PX/OO in these parts.
What triggers a product safety recall? Does there need to be a design error or a provable manufacture QC problem? Why was there not one in this case? Who triggers one? Would the insurer be involved?
Unless it was designed to be carbon and replaced?
I've worked closely with this. A part made by a third party contractor, initial test and production samples passed testing, later ones started failing in the field, and when reviewing sample testing, were passing inspection with *far* lower margins.
Turns out that they'd maxxed out all the infill allowance and minimised the quantities of the expensive bits. The parts were even measurably heavier, couldn't hold dimensional stability (would warp when they got the sun on them).
Shouldn’t all bikes with this fork (or close variants) be recalled?
I was impacted by the Kinesis recall, had to get two forks replaced, a bit of digging on manufacturing codes, OE catalogues and so on showed that the same fork, with different paint and drop outs was on at least half a dozen other bikes that a mate and i could find, it appeared that some came from the same factory, some were from another one. So i *really* hope it was just a straightforward faulty batch, as only Kinesis forks were recalled...
There was a good challenge to the efficacy of xray and ultrasound use like that a while back, about ability to interpret the signal or read outs and how it was pointless unless real time was spent on the parts, time that simply wasn’t in the usual production QC process. Was interesting but I can’t remember whose it was.
A colleague of mine quite literally wrote one of the manuals on NDT/DT testing of composites.
Was then hounded off weightweenies (i think) for pointing out the pointlessness of the 100% x-ray process that Canyon do when it was suggested that all manufacturers should do this "as standard" on all composite parts.
Was then hounded off weightweenies (i think) for pointing out the pointlessness of the 100% x-ray process that Canyon do when it was suggested that all manufacturers should do this “as standard” on all composite parts.
Would be really interested to hear more from him on that point if he put anything in writing or you had a link. tbh I can't remember if the point I read about was RE ultrasound or xray, though the interpretation and time needed might count for either.
What triggers a product safety recall? Does there need to be a design error or a provable manufacture QC problem? Why was there not one in this case? Who triggers one? Would the insurer be involved?
PAS 7100 if interested in the details, it's free to download
Would be really interested to hear more from him on that point if he put anything in writing or you had a link.
I'll ask him if i remember next time i speak to him. Got no link as i'm only on here and Retrobike as far as cycling forums go!
Hmm what does happen in these scenarios, your riding along then your whole world is effectively gone in one second.
You can't work therefore can't pay your mortgage, I suppose you may have some insurance but then there's a lifetime of extra costs for you new requirements.
TBH I think its a 'there for the grace of god', I've broke pedals and chains and bounced off stuff and slide down roads ,bounced over handlebars on more than one occasion., like most of use , but it does make me wonder.
Hmm what does happen in these scenarios, your riding along then your whole world is effectively gone in one second.
You can’t work therefore can’t pay your mortgage, I suppose you may have some insurance but then there’s a lifetime of extra costs for you new requirements.<br /><br />
I think thats why we’re recommended to take out critical illness as part of life insurance.
Are there honestly people out there who can't bring themselves to click a daily mail link?
grimep
Free Member
Are there honestly people out there who can’t bring themselves to click a daily mail link?
Yep
Are there honestly people out there who can’t bring themselves to click a daily mail link?
Absolutely. Stop Funding Hate.
It's carried on GCN too.
