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CT a crashed frame?

Old 05-18-19, 05:41 PM
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jack k
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CT a crashed frame?

I was hit by a vehicle a little while ago on a 2013 Devinci Leo, carbon endurance frame. I think my chin took the brunt of the impact tbh. The frame definitely bounced off of the road but the wheels and handlebars were the contact points, there is a bit of scuffing on the fork. Other than that the frame actually looks okay. I am trying to determine whether to rebuild the frame or hang it up as wall art.

Apropos that, I made friends with a diagnostic radiological technician who runs a CT scanner at my place of work - I may be able to run the frame through it if the circumstances are right. Would a negative scan (assuming disruptions in the structure would scan the way that a broken bone does) be sufficient to put the frame back on the road? Is this even a thing? What about ultrasound?
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Old 05-18-19, 06:48 PM
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Sounds intriguing. However, a few caveats: first, CT uses computer algorithms to interpret X-rays fired through the body, to visualize tissues in virtual ďslicesĒ - Iím not sure that the computer will interpret a bike frame correctly to the extent that youíll see anything as small as a crack. CT also makes use of X-ray-opaque tracers to enhance and visualize features. This wonít be available to you. Also, CT tunnels are pretty tight - will your frame fit? Lastly, these are very hi-tech machines - expensive to run, maintain and repair. If I were a supervising radiologist and I found out that one of my techs had been using the CT to scan a friends bike, Iíd be pretty pissed. I donít know your colleagues circumstances, of course, but unless he has agreed to do this, I donít know that Iíd put him on the spot.
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Old 05-18-19, 06:56 PM
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I do not know the answer to the CT or ultrasound. If I was having either test done to myself I would be concerned about the testing facility if I saw or knew that a test was allowed to be performed on someones bicycle. As for actually determining damage to the frame, I would certainly have it checked out by a qualified person/facility in an apropos way. Just eyeballing it and seeing no cracks/damage is not enough. If it is being ridden with damage it is possible, or even likely, that it would have a catastrophic failure.
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Old 05-18-19, 07:02 PM
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Originally Posted by jack k View Post
...I think my chin took the brunt of the impact...

All you need in this life is ignorance and confidence, then success is sure. - Mark Twain
You said it. (Also get checked for concussion.)
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Old 05-19-19, 12:23 PM
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Apparently, industrial CT scanning is a real thing. https://diversedimensions.com/

Having a frame scanned in a healthcare facility is pretty questionable, though.
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Old 05-19-19, 01:13 PM
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Asking Why ? You have one ?
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Old 05-19-19, 01:56 PM
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A few years back, one of the locals that frequented our LBS had brought in a full suspension Yeti downhill frame. It had a light crank in it and was being covered under warranty. I happened to be around that time and they said, "See if you can find the crack." I looked for a good 20 minutes along with others and we couldn't find it. Finally the frames owner pointed out the crack. Sure enough, there was a crack and he got a new frame out of it. This was all done with a bare frame.

If you are considering riding it more, which I would do if there were no obvious cracks or creaks, I'd strip it down and clean it as good as possible, Get every bit of grease and dirt off of it and go over it with a fine tooth comb. I would then take it a competent bike shop and have them give it a once over. Have others look at it too.

I got put down on my Giant TCR by a dog a couple of years ago. The saddle, pedals handlebars and skewers were what took the majority of the impact with the road. It was none the worse for the wear. But then there is Crazy J**** who got hit by a car, didn't pay any attention to his frame and kept riding in his manner, Hence the name "Crazy". Going up Buffalo Mountain one day, the frame gave way. So, it is very very important to look these things over if there has been a frame impact.
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Old 05-20-19, 06:13 AM
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Is the motorist at fault? And if so, is his/her insurance covering this incident? If so, insist they buy you a new frame. If necessary, take your bike to a shop and ask them to verify that it is crack-free; they can't and won't, and will likely tell you (and the insurance company) that they can't verify the frame's safety.
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Old 05-20-19, 12:10 PM
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Most of the CF inspections I see are ultrasonic. The low Z of carbon (and oxygen, etc.) is too low for most X-rays to see anything.
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Old 05-22-19, 05:16 PM
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Jack.
I left the cycling industry about 40 years ago and moved into golf. I am now moving back, but my experiences there taught me a bit about Carbon Fibre.
The only way to find a break or defect in CF is an X-ray. In the new layered frames and in INDY CAR, the only way to test is again, X-ray. CF breaks down in spider cracks through the shell around the point of impact. In golf shafts it is always from a miss hit; where the shaft impacts with a stationary ball at 100+ mph. The carbon fibre shatters in a splinter pattern radiating from the point of impact. Same happened when we X-rayed the tubs of Indy cars with a specific point of impact. Spider cracks radiating from center.
So with a bike; It would need an X-ray to find damage, and that won't be cheap! If you think there is damage... there likely is! And it is better to buy a new frame than look for a way to X-ray it. The costs would be higher to find a crack than it will be worth, and if you find it, you will still need to replace the frame.
When a golf shaft breaks from impact damage, the worst case is someone gets hit with a driver head that is flying erratically. When a CF bike explodes the rider usually gets a serious injury. Why would you take a chance?
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Last edited by Mad Honk; 05-22-19 at 05:18 PM. Reason: spelling
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