#21
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Cannondale recall
On Friday, July 26, 2019 at 1:25:45 PM UTC-7, AMuzi wrote:
On 7/26/2019 2:11 PM, Tom Kunich wrote: On Friday, July 26, 2019 at 5:17:47 AM UTC-7, AMuzi wrote: On 7/25/2019 10:48 PM, Frank Krygowski wrote: On Thursday, July 25, 2019 at 6:32:51 PM UTC-4, AMuzi wrote: On 7/25/2019 2:52 PM, Frank Krygowski wrote: https://gearjunkie.com/cannondale-ca...bicycle-recall Hmm. The carbon fiber fork may kill you. But on the other hand, it's nice and light! - Frank Krygowski Well, that's true but the history of recalled forks includes steel and aluminum models as well. Agreed. My Reynolds 531 tandem fork failed. But that builder error - by builder Jim Bradford. - Frank Krygowski You've mentioned that before and of course we see occasional anomalies/errors too. In everything. But a fork recall happens when design/engineering/material/process has systematically failed for a particular run of product. Different thing entirely. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 "systematic failure" could be a half dozen forks all failing in the same manner. But consider - fork failures are all pretty much the same - steel forks bend almost in the same position on all steel bikes. Aluminum forks all fail just above the dropout or at the connection between the fork and the head. I'm sure it has happened but I haven't seen modern carbon fiber forks fail except in collisions. Right. Recalls are response to a pattern indicating systemic failure to some significant level (as opposed to one-off anomalies). Uh, "Fork failures are all..." is not quite true. Steel- The recalled Bridgestone X-01 fork steerers fell out of the crowns. Motobécane Grand Touring/Mirage forks had ends not brazed in, and yet plated over Viscount recalled aluminum cast forks had random voids in the lower piece. The steel columns were never a problem. Peugeot Comete cold process aluminum forks had crown casting voids as well. Panasonic bonded aluminum tubes had bond problems (not clean? wrong epoxy? no idea) Carbon forks have been recalled for voids but also for crown-to-column bonding with steel and aluminum columns. If you're talking about crash damage as opposed to recalls that's also not right. Although many if not most steel blades curve back in the top 1/3 of the blades when smacked: http://www.yellowjersey.org/photosfr...t/NIMGAFRK.JPG Forks also snap off ends, bend or crack steerers and twist too. I see more wrecked frames than most guys and categorical statements don't match what I see. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 I will take your word for it but all of the steel fork failures were exactly like the on in your picture - the upper third of the fork bent since that is where the highest leverage is. I saw them fail not just in accidents such as auto collisions but even early unsuspended MTB's would bend there simply descending through broken ground. By my cousin's house it the hill that Bontrager and the others used to descend on those old Schwinns and Raleighs and it wasn't unusual to see a bike by the side of the road there with the bent fork. I'm sure you've seen a lot more failures though so I accept your comments as from an expert. |
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#22
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Cannondale recall
On Saturday, July 27, 2019 at 9:34:12 AM UTC-7, sms wrote:
On 7/27/2019 7:34 AM, jbeattie wrote: snip The fact is, we don't know what deaths were or were not caused by carbon fork failures. We pretty much do. The fork fails, the rider crashes and dies. The death is attributed to fork failure. Yes, there may have been contributing factors to the fork failure other than a manufacturing defect and a fork that never had experienced any trauma may not have broken. There are no seatbelts on a bike, and when a rider hits a rock or wall or curb or dog, he or she is going to get launched. What happens to the bike is often irrelevant -- but when a rider gets off the ground and sees a broken fork or frame, it is immediately presumed the crash was caused by the failure rather than vice-versa. Yes, there are CF for failures and recalls, and I'm not giving the industry a free pass, but considering the millions of CF forks in existence, there clearly is no epidemic of CF fork-induced deaths. Not an epidemic, but about Phase 3 of a pandemic. Just to be safe you should order some Rivendell forks when they are back in stock https://www.rivbike.com/products/carbonomas-steel-fork-1-1-8-threadless-curved. But there is no disc brake model. Soma Fabrications is another good source for you to consider when replacing all the carbon forks in your fleet with steel forks, see https://www.somafab.com/parts/forks. That high speed crash into a stone culvert a couple of years ago pretty much showed just how strong Carbon Fiber forks are. I dropped down into the culvert at least at 20 mph. The shock of the sudden stop made every bone in my body hurt but luckily no serious damage. Later looking at the fork layup just above the drop-out on the right side of the fork was cracked. Originally I assumed that was why I lost control of the bike but later with a clear head it dawned on me that if it had been cracked and that caused my loss of control that it would have broken off in the extremely violent collision. So that Colnago fork really took a collision strike FAR above what you could expect and had relatively minimal damage. If I wasn't afraid that every bone in my body was broken I could have carefully ridden it home. |
#23
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Cannondale recall
On Saturday, July 27, 2019 at 11:19:32 AM UTC-7, Frank Krygowski wrote:
On Saturday, July 27, 2019 at 12:34:12 PM UTC-4, sms wrote: On 7/27/2019 7:34 AM, jbeattie wrote: snip The fact is, we don't know what deaths were or were not caused by carbon fork failures. We pretty much do. The fork fails, the rider crashes and dies. Or just as probable, "The rider crashes and dies, and the fork was broken." The fork may have broken incidentally, not as a cause. There are accident reconstructionists who attempt to determine causes of such things, and their work is not simple. BTW, the same thing happens with many other types of mechanical failures. I've done a little of that sort of analysis for litigation, and had colleagues who did a lot of it. Just to be safe you should order some Rivendell forks ... Oh my gosh, we must do everything we can to improve safety! The trouble with Rivendell forks is they are still hollow. Can you imagine? A hole right up the middle! We need to return to the solid forks of yore. - Frank Krygowski OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them. |
#24
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Cannondale recall
On Saturday, July 27, 2019 at 8:09:58 PM UTC-4, Tom Kunich wrote:
OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them. Sure. What do you want to know? You can look up "Stress = M * c / I" to begin your home study. Let me know what questions you have. - Frank Krygowski |
#25
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Cannondale recall
On Sat, 27 Jul 2019 19:58:47 -0700 (PDT), Frank Krygowski
wrote: On Saturday, July 27, 2019 at 8:09:58 PM UTC-4, Tom Kunich wrote: OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them. Sure. What do you want to know? You can look up "Stress = M * c / I" to begin your home study. Let me know what questions you have. - Frank Krygowski A guy on another group who identified himself as "BSc (Hons) wrote in answer to a similar question, "I have a study I did on this sort of thing from my first year at university on my hard drive at home- I will upload my report when I get back from work and see if it helps." Perhaps a limited education is a bit limiting :-) -- Cheers, John B. |
#26
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Cannondale recall
On Saturday, July 27, 2019 at 9:34:12 AM UTC-7, sms wrote:
On 7/27/2019 7:34 AM, jbeattie wrote: snip The fact is, we don't know what deaths were or were not caused by carbon fork failures. We pretty much do. The fork fails, the rider crashes and dies. The death is attributed to fork failure. Yes, there may have been contributing factors to the fork failure other than a manufacturing defect and a fork that never had experienced any trauma may not have broken. I'll pretend you're being serious. You're assuming cause and effect. It could have been rider crashes, fork fails and rider dies. Or rider dies, crashes and fork fails. Or it could have been fork fails, rider crashes and dies. We don't know which one it was. Maybe somebody does, but one line in a story isn't enough. CPSC reporting has to be made in a short time frame and is based on second-hand reports. It's not the result of lengthy investigation and testing. This was a voluntary recall and not CPSC mandated. Cannondale was concerned enough to recall three years of CAADX forks, but according to the story, its actual testing of products showed no problem -- which means they went out and got some old CAADX forks from consumers since they don't keep a bunch of NOS forks around. There are no seatbelts on a bike, and when a rider hits a rock or wall or curb or dog, he or she is going to get launched. What happens to the bike is often irrelevant -- but when a rider gets off the ground and sees a broken fork or frame, it is immediately presumed the crash was caused by the failure rather than vice-versa. Yes, there are CF for failures and recalls, and I'm not giving the industry a free pass, but considering the millions of CF forks in existence, there clearly is no epidemic of CF fork-induced deaths. Not an epidemic, but about Phase 3 of a pandemic. Just to be safe you should order some Rivendell forks when they are back in stock https://www.rivbike.com/products/carbonomas-steel-fork-1-1-8-threadless-curved. But there is no disc brake model. Soma Fabrications is another good source for you to consider when replacing all the carbon forks in your fleet with steel forks, see https://www.somafab.com/parts/forks. I'm going to buy my twin top-tube Homer Hillbilly frame and fork today. BTW, the CF fork on my 2017 CAADX is super-beefy. Steel probably wouldn't be much of a weight penalty. The bike rides like a pig because of the over-all weight and the slack front end. My son has elected a non-epic ride today in SLC because he also wants to do another hike with me and my wife later in the day -- so no Empire/Guardsman Pass (fwew). Probably something shorter and less elevation. I'll be on the CAAD 9 with a (I believe) Kinesis CF fork. That is a great bike, and the wheels that I built for my son years ago are spot-on. -- Jay Beattie. |
#27
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Cannondale recall
On 27/07/2019 20:19, Frank Krygowski wrote:
snip The trouble with Rivendell forks is they are still hollow. Can you imagine? A hole right up the middle! We need to return to the solid forks of yore. Frank has it spot on. If only they'd go through the simple p[process of turning the fork inside out, moving the hole to the outside where it would cause less trouble, we wouldn't be having these recalls. |
#28
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Cannondale recall
On 7/28/2019 7:36 AM, jbeattie wrote:
On Saturday, July 27, 2019 at 9:34:12 AM UTC-7, sms wrote: On 7/27/2019 7:34 AM, jbeattie wrote: snip The fact is, we don't know what deaths were or were not caused by carbon fork failures. We pretty much do. The fork fails, the rider crashes and dies. The death is attributed to fork failure. Yes, there may have been contributing factors to the fork failure other than a manufacturing defect and a fork that never had experienced any trauma may not have broken. I'll pretend you're being serious. You're assuming cause and effect. It could have been rider crashes, fork fails and rider dies. Or rider dies, crashes and fork fails. You wouldn't have hundreds of fork recalls for these cases. |
#29
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Cannondale recall
On 7/28/2019 10:06 AM, Tosspot wrote:
On 27/07/2019 20:19, Frank Krygowski wrote: snip The trouble with Rivendell forks is they are still hollow. Can you imagine? A hole right up the middle! We need to return to the solid forks of yore. Frank has it spot on.Â* If only they'd go through the simple p[process of turning the fork inside out, moving the hole to the outside where it would cause less trouble, we wouldn't be having these recalls. Actually a hollow fork will be stronger than a solid fork. A hollow tube is stronger than a rod of equal mass (assuming the same material). As the inside diameter increases the tube becomes stronger. You can increase the diameter to compensate for a weaker material. This is why aluminum frame tubes have to be of greater diameter than steel frame tubes. Surprised that Frank would not know about this since it is basic physics and material science. |
#30
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Cannondale recall
On 7/28/2019 6:33 PM, sms wrote:
On 7/28/2019 7:36 AM, jbeattie wrote: On Saturday, July 27, 2019 at 9:34:12 AM UTC-7, sms wrote: On 7/27/2019 7:34 AM, jbeattie wrote: snip The fact is, we don't know what deaths were or were not caused by carbon fork failures. We pretty much do. The fork fails, the rider crashes and dies. The death is attributed to fork failure. Yes, there may have been contributing factors to the fork failure other than a manufacturing defect and a fork that never had experienced any trauma may not have broken. I'll pretend you're being serious. You're assuming cause and effect. It could have been rider crashes, fork fails and rider dies. Or rider dies, crashes and fork fails. You wouldn't have hundreds of fork recalls for these cases. Hundreds of forks per recall does not mean the same thing as 'hundreds of recalls'. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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