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Old May 30th 17, 02:58 PM posted to rec.bicycles.tech
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Default Carbon Bikes and Quality Control

On Monday, May 29, 2017 at 11:39:38 AM UTC-7, wrote:
On Monday, May 29, 2017 at 10:40:18 AM UTC-5, wrote:
Quality control for metal bikes is relatively easy - especially for steel since all of the important connection can be seen on the workmanship.


Quality control for metal bikes is easy? With brazing and lugs, no longer used, you cannot see or tell if the brass/silver has covered the entire inside surface of the lugs. Just have to hope. And with welding, TIG, the surface weld is not the only story. You have to look at the inside too. This will tell if the penetration is correct. The surface can be nice and neat but if the weld does not penetrate the correct amount, then its just appearance and its a poor weld. Do you think every frame company takes a microscope or camera and looks at the inside of every weld? Or more likely the guy taking the frame off the welding rack just glances at the welds and says looks good.




Now my experience has shown me that CF is not reliable.

So what we need is more information on the percentages of CF bikes that are having quality control problems.



I assume others have asked, but please enlighten us about all the experience with carbon fiber you claim to have. I'm guessing the experts have chemical engineering degrees and have observed hundreds or thousands of controlled experiments involving carbon fiber. Have you owned thousands of carbon frames and thousands of carbon handlebars and thousands of carbon cranksets and thousands of carbon rims from many, many makers? That must cost you millions and millions of dollars to buy these test samples. And the time to test all these samples must be enormous.

I suspect the percentage of carbon frame bikes having problems is the same percentage of aluminum or steel frames having problems.



Question - are the pro level bikes that are breaking so often custom built in their company's racing labs so that the quality control is much lower than the assembly lines in China or Taiwan?



Pro bikes break often? Now I have seem a few frames break on TV races. When there is a big crash at 35 mph and ten riders and frames all go flipping into the air and sliding on the pavement, some of the bikes break. But usually you see a rider with half his clothes ripped off and blood running down his legs, arms, and face try to get back on his still operating bike and ride down the road. Sometimes someone will come off the sidelines and grab him and make him stop because he is wobbly and has a concussion. But the bike still works after the crash. Pro teams may retire/scrap the frame that night because after the crash it is just not trusted anymore. And does not look good either.


Excuse me Russel - if you don't know how to tell that a brazed joint is totally filled you aren't a metal worker. Within ten minutes of using a torch I could tell you. This isn't anything difficult. A brazed joint is not a weld. They are not referred to as a weld.

And yes I have asked. But companies are not forthcoming about this. Privately I'm told that the super-lights have a LOT of breakage. I assumed this to be normal breakage but after researching the material more discovered that as the engineers at these companies are saying, properly done these CF frames can last a lifetime. This leaves the only excuse for the amount of breakage the almost impossible task of quality control on a frame that is built from the inside out and hence having all of the mistakes covered up where they can't be seen. Some companies are using ultra-sound to detect problems but they still seem to have problems. I assume this is because the defects that cause problems are simply too small for ultra-sound to detect.

If you don't know what's breaking in the pro peloton then you aren't going to be convinced by me telling you that I've chased this around and heard from pro mechanics about massive failures of these bikes. That many of the riders go through a dozen bikes in a grand tour. That all you have to do is compare the "retirement" list of modern races with those from the time of LeMonde.
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