tag:blogger.com,1999:blog-13887692.post1561680402262699656..comments2024-03-13T02:16:08.135-04:00Comments on Cozy Beehive: Thomson Elite Seatpost FailureRon Georgehttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comBlogger64125tag:blogger.com,1999:blog-13887692.post-53053100254740347402012-07-22T17:53:37.935-04:002012-07-22T17:53:37.935-04:00I have had two of these Elite posts break off at t...I have had two of these Elite posts break off at the front ear section. Yes they were torqued correctly, so thats not an issue here and I dont ride in the rain unless I get caught in it and my bikes are kept spotless, so abuse and corrosion are not an issue for this failure. <br />The bikes did not have any falls either at this time or in the past so its not a striking issue to the posts etc.<br />Heres something thats amazed me about the breaks on these two posts, one was a 27.2 and the other a 31.6. On both posts they snapped of when the bikes were not being ridden. <br />The bikes were parked in my bike room and suddenly there was a "popping" sound, after which the saddle flopped down.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-2152690138804866492012-04-26T17:58:28.694-04:002012-04-26T17:58:28.694-04:00On the day after Thanksgiving, 2010, the Thomson E...On the day after Thanksgiving, 2010, the Thomson Elite seatpost on my LiteSpeed Vortex failed catastrophically during a right turn, sending me to the pavement. Bottom line, after a trip to ER, x-rays, CT scans, and a night in the hospital, I had a broken scapula and multiple broken ribs that took 10 weeks to heal. I have a photo of the failed seat post if anyone is interested. My LBS contacted Thomson and their response was what others have reported: can't happen without extreme abuse not associated with normal riding.<br /><br />If anyone is interested in the photo, let me know.<br />Believe me, that's BS.<br /><br />D. HoltAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-67057757615395130852011-11-17T00:12:34.315-05:002011-11-17T00:12:34.315-05:00This thread, and the others, make me wish I had ph...This thread, and the others, make me wish I had photographed and saved all the broken Thomson seatposts and stems that's come through my shop over the past few years. I'd guess I've seen probably ten or so Thomson products with cracks, and one or two that failed catastrophically and without warning. <br /><br />Their warranty process is actually rather annoying, since they don't issue RAs (return authorizations) and no one on the phone is interested in hearing what you have to say about how or why the product failed. You just dump it in an envelope and send it back to them. Sometimes Thomson replaces them, sometimes they send the product back to you with a scribble that says "Not warranty" or some such vague comment.<br /><br />Meanwhile, I've yet to see a decent cold-forged aluminum seatpost or stem fail without provocation. Mind you that these products are generally lighter and less expensive than the Thomson equivalent.wolberhttp://wolberpiste.comnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-69429013699259043712010-10-25T18:39:27.705-04:002010-10-25T18:39:27.705-04:00Boycott American junk.Boycott American junk.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-87821126539304392752010-09-22T21:16:50.403-04:002010-09-22T21:16:50.403-04:00I realize this post is over 1 1/4 years late, but ...I realize this post is over 1 1/4 years late, but i have a Thompson Elite Post that cracked in almost an identical spot. I weigh 140 lbs. was riding along (out of the saddle at the time) go to sit down and my saddle is floating. I thought for sure a rail on the saddle came loose. I stop and look and see a crack at almost the exact spot as the OP's seatpost. Very weird indeed, I have never seen anything like this at all; no impact, no new adjustment, just up and died on me.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-12743778619201388842009-04-17T09:55:00.000-04:002009-04-17T09:55:00.000-04:00Dave : Thanks for writing in. I think we all agree...Dave : Thanks for writing in. I think we all agreed that 60 in-lbs is not a lot of torque, may be hard to dial in without a torque meter and its likely the rider may have overstepped on the tightening. From his initial response to me, it seems he had been riding on the seatpost for a year without doing any work on it. So did he overtighten initially and then it failed a year later? <br /><br />Did you also look at the failure of another setback post?<br /><br />Here's the link : http://cozybeehive.blogspot.com/2009/04/thomson-elite-setback-post-failure.html<br /><br />Would you like to comment on that?Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-2384692545667710212009-04-17T09:13:00.000-04:002009-04-17T09:13:00.000-04:00This is Dave from Thomson, email is dparrett@lhtho...This is Dave from Thomson, email is dparrett@lhthomson.com . First, we will replace a failed part out of goodwill. Second, you simply can't generate enough force riding to break the front ear of the post. That failure is from overtorque. From past experience the bolts were probably near yield at 125+ inch pounds.David Parretthttp://www.lhthomson.comnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-33503552074148839552009-04-12T02:22:00.000-04:002009-04-12T02:22:00.000-04:00Anon : Thanks for the tip-off. Duly noted!Anon : Thanks for the tip-off. Duly noted!Unknownhttps://www.blogger.com/profile/12256394060474969622noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-25759299003219068102009-04-11T22:15:00.000-04:002009-04-11T22:15:00.000-04:00http://forums.mtbr.com/showthread.php?t=508685Hmmm...http://forums.mtbr.com/showthread.php?t=508685<BR/><BR/>Hmmm. Link above is a catastrophic failure of a Thomson Layback/Setback.<BR/><BR/>Found the blog here after casually googling around for other Thomson post failures. Seems very rare.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-6537471665778831622009-03-26T22:45:00.000-04:002009-03-26T22:45:00.000-04:00Do you recall how the bike fell (orientation)?It f...<B>Do you recall how the bike fell (orientation)?</B><BR/><BR/>It fell sideways. I picked it up by handlebar and the saddle and the back part broke off in my left hand.<BR/><BR/><B>Were you riding it when this happened (added weight) or did it free fall as it tipped over (just the bike weight).</B><BR/><BR/>It was leaning against the wall when it tipped over.<BR/><BR/><B>The broken part in question faces the north-south direction (front-rear) and doesn't stick out sideways. Which is why I'm curious. Did the seatpost also have the saddle attached during that time?</B><BR/><BR/>Yes, the clamp was secure and undamaged, and still attached to the saddle. <BR/><BR/><B>The manual was in the "useless" bag. I wonder if you ever referenced it.</B> <BR/><BR/>Yes I did and didn't find it useless at all.Archtop Soulhttps://www.blogger.com/profile/00411582948991168076noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-57258545753113206592009-03-25T17:04:00.000-04:002009-03-25T17:04:00.000-04:00Michael at 7:58 - Thanks for reading. I do not was...Michael at 7:58 - Thanks for reading. I do not waste time in amassing all field reports out there, but if I find out something critical and in need of pollination, I will dig into the details and do a writeup. <BR/><BR/>There's too many stories out there without credible sources and background info in them. For example, see <BR/><A HREF="http://bustedcarbon.blogspot.com/" REL="nofollow">Busted Carbon</A>, a blog that tirelessly wastes time trying to ridicule carbon fiber composites by posting anonymous pictures of broken parts, without citations and background information. You might as well think they were all photoshopped!Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-75174963855235059822009-03-25T13:00:00.000-04:002009-03-25T13:00:00.000-04:00Cafiend at 9:15 : You're right. The heaviest load ...Cafiend at 9:15 : You're right. The heaviest load is the rider.<BR/><BR/>Torsional moment = Load x Moment Arm<BR/><BR/>Place a 200 pound rider at an inch away from the center of the clamp site and you have 200 in.lbs of torque. This seatpost is designed to 'give' or bend (aka yield) at 250 ft. lbs of torque, and catastrophically failing at 350 ft. lbs extreme. Now that is a huge cushion. <BR/><BR/>Marketing materials also claim the post is designed to bend at severe impact loads. Did not happen here. Maybe true for the tube itself but the ear in this case broke off.Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-84492514090359978832009-03-25T12:32:00.000-04:002009-03-25T12:32:00.000-04:0060 in-lbs is not a lot of torque. With adequate ex...60 in-lbs is not a lot of torque. With adequate experience tightening and loosing bolts, any person can go by 'feel' and tighten by hand. You don't and I repeat, you don't need to purchase a 50 dollar torque wrench just to tighten bolts on your seatpost. If you're not confident about it, hand it to your LBS and they'll take care of it.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-69595709745236561202009-03-25T12:16:00.000-04:002009-03-25T12:16:00.000-04:00Mark : I have heard about hydraulic and electrical...Mark : I have heard about hydraulic and electrical fuses but this structural fuse is new to me.<BR/>I'm somewhat familiar with the steel catapult material that acts as a mechanical fuse on aircraft carriers to launch fighter planes.<BR/><BR/>Please send some well reviewed literature my way and I'll be happy to learn.<BR/><BR/>As for the discussion between the both of us, this is getting way out of hand. The failure occurred at the ear on impact. The upper faces of the ear has sharp features due to machining and one line of thinking that those could generate stress-risers cannot be disagreed with. My other question is whether a bicycle tipping over from a supporting wall that could otherwise be harmless generate enough impact torque to severe the ear of the post. <BR/><BR/>Paul at 9:32 said : <B> 60 inch pounds = 5 foot pounds = NOT VERY MUCH PRESSURE. Without a torque wrench it would be very hard to know if it was overtightened.<BR/>A proper metalurgical analysis would reveal the failure mechanism.<BR/></B><BR/><BR/>60 in-lbs is not a lot of torque. You're right. Its like a 60 inch steel bar with one pound of force at the end.Unknownhttps://www.blogger.com/profile/12256394060474969622noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-69909141008194521262009-03-25T11:42:00.000-04:002009-03-25T11:42:00.000-04:00Ron wrote: Since Thomson has not stated that the b...Ron wrote: <B>Since Thomson has not stated that the bending fuse is the elliptical inner cross section, I will not do so either.</B><BR/><BR/>Go read up on the concept and use of a 'structural fuse'.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-54224793913432933292009-03-25T11:25:00.000-04:002009-03-25T11:25:00.000-04:00Mark : True. From the design, the major axis of th...Mark : <BR/><BR/>True. From the design, the major axis of the ellipse has been oriented to be parallel to the more probable of the planes of bending.<BR/><BR/>The OD of the seatpost is not oval, as you claim as it would never fit into the seat tube. The OD is circular.<BR/><BR/>Again, its all in the details. I don't have a whole lot of experience with patents, but one would think that in an official document against the invention, a complete description of what the 'bending fuse' is and in what area of the seat post this is incorporated would be stated explicitly. Patents are read by different set of eyes. What intuition led you to believe is not what someone else could see. <BR/><BR/>Hey, you were the one calling for "facts".<BR/><BR/>Since Thomson has not stated that the bending fuse is the elliptical inner cross section, I will not do so either.Unknownhttps://www.blogger.com/profile/12256394060474969622noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-88947420444286944342009-03-25T10:59:00.000-04:002009-03-25T10:59:00.000-04:00Ron wrote If you have any more explanations to mak...Ron wrote <B>If you have any more explanations to make the bending fuse a legit innovative idea, let me know. But for now, I feel the term is misleading in that I thought it was a separate component on the seatpost.</B><BR/><BR/>Good grief... The bending fuse is a 'failure mode'. Now, what is it about the Thomson seat post shaft's design that makes it unique AND that would cause it to bend and fold instead of fracturing? <BR/><BR/>Look at your own post again and the design drawings and you'll see that while the post has an oval outer diameter (OML), the inner diameter (IML) is ovalized such that the side walls are thinner than the fore and aft walls instead of being symmetric around the entire shaft. <BR/><BR/>Intuitively, one would expect the sidewalls to deform well before the yield strength of the thicker fore and aft cross sections of the shaft were reached and thereby allow the post to fold instead of fracturing and that's what I believe is described in their Patent and conveyed in their literature, albeit in less that explicit terms.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-52985211351714257342009-03-25T10:48:00.000-04:002009-03-25T10:48:00.000-04:00In my opinion, I see this bending fuse idea as not...<B> In my opinion, I see this bending fuse idea as nothing more than that extra safety factor, which is nothing new and has been known in engineering since the Byzantine empire. To say that this idea is not used by other seat post manufacturers (or prior art) is...well, is that really true? </B><BR/><BR/>Ron - Maybe they meant that similar lightweight (weightweenie) posts in the market favor lightweight over strength and factor of safety. I'll be hard pressed to believe that commonly used, mainstream AL seatposts don't take factors of safety into account.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-74722526821872823592009-03-25T10:43:00.000-04:002009-03-25T10:43:00.000-04:00For further reference to bending fuse being nothin...For further reference to bending fuse being nothing more than factor of safety :<BR/><BR/><BR/>Elite seatposts are 40% stronger in ultimate strength tests, and have twice the fatigue life of the 75 strongest production seatposts on the market. Further, all Thomson posts are designed with a bending fuse so they bend slightly at their failure point, rather than snap completely, to allow for a safe failure.<BR/><BR/><BR/>Link : http://www.lhthomson.com/docs/LHT_2005_products.pdfRon Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-50993315303715649662009-03-25T10:24:00.001-04:002009-03-25T10:24:00.001-04:00Mark,Thanks for the info. However, its very limite...Mark,<BR/><BR/>Thanks for the info. However, its very limited in explanation. The website link has nothing technical about the bending fuse. There's two instances of bending fuse mentioned in the patent 5,664,829 (pages 9 and 11 as per search) that is also very limited in explanation in what it is exactly from a materials and design standpoint, save for the fact that they mention its purpose is to prevent catastrophic failure.<BR/><BR/>What do I think of the bending fuse? Thomson designers were aware of fatigue limitation of aluminum and added in an extra factor of safety (or overbuilt it) to cushion against catastrophic failure. They use a special term for this called "bending fuse". In my opinion, I see this bending fuse idea as nothing more than that extra safety factor, which is nothing new and has been known in engineering since the Byzantine empire. To say that this idea is not used by other seat post manufacturers (or prior art) is...well, is that really true?<BR/><BR/>If you have any more explanations to make the bending fuse a legit innovative idea, let me know. But for now, I feel the term is misleading in that I thought it was a separate component on the seatpost.Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-79396568999040498732009-03-25T09:32:00.000-04:002009-03-25T09:32:00.000-04:0060 inch pounds = 5 foot pounds = NOT VERY MUCH PRE...60 inch pounds = 5 foot pounds = NOT VERY MUCH PRESSURE.<BR/><BR/>Without a torque wrench it would be very hard to know if it was overtightened.<BR/><BR/>A proper metalurgical analysis would reveal the failure mechanism.Paulhttps://www.blogger.com/profile/12582339703208909395noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-76772721026181938162009-03-25T07:58:00.000-04:002009-03-25T07:58:00.000-04:00Regarding email address snafu - judging from the p...Regarding email address snafu - judging from the passion in responses and probable viral spread of this issue, it is not unlikely that the email inbox has overflowed often, and has been disabled<BR/><BR/>I own a Masterpiece and an Elite seatpost, and a 73 deg stem. All doing quite well.<BR/><BR/>I had a Kalloy seatpost break at the clamp. There was a small burr that scored the seatpost. I assume that initiated the problem that repeated stress over time finished the job. Point is that Kalloy posts are simple, overbuilt, heavy sticks of aluminum. So if anybody is thinking of abandoning Thomson posts for a heavy stick of aluminum they should be aware that cheap and heavy stuff breaks too.<BR/><BR/>I appreciate this blog's analysis of engineering vs marketing vs field reports. I appreciate the opinions too whether I agree or not. The ball belongs to Thomson now. I'd like to see the blog author take up a discussion with Thomson and 99.99% of the others of us not get involved directly with the mfr.<BR/><BR/>I offer this comparison. Think of an airplane mfr. Have their products failed catastrophically? Have those failures prevented you from flying? It's all about the percentages. This incident doesn't strike me as a marketing fail. I guess all marketing blather is doomed to failure by some measure. I ignore the stuff unless it's annoying or funny. I bought Thomson products based on user reviews on the web and technical specs from the mfr. <BR/><BR/>Just started reading this blog. Very nice. Thanks for the effort.Michaelhttps://www.blogger.com/profile/15899082331895945313noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-63397649470360318652009-03-25T07:17:00.000-04:002009-03-25T07:17:00.000-04:00What stumps me is that for all that marketing on t...<B>What stumps me is that for all that marketing on their website, there is actually no bending fuse description on the instruction sheet. I'd actually like to see a description of this and how it works. Is this incorporated into the top and bottom clamp design somehow, and not mentioned? </B><BR/><BR/>Bending fuse refers to the failure mode of a Thomson seat post shaft vs. fracture / shearing-off. You can find it mentioned in their FAQs on carbon seat posts: http://www.lhthomson.com/carbon_seatpost.htm<BR/><BR/><I>We designed the Thomson post to bend above the max line, bend-not break. We designed all of the clamping mechanism to be stronger than the post so that no matter what, the saddle stays with the post in a failure. We received a patent for this failure mode; we call it our bending fuse.</I><BR/><BR/>For a more technical description you can refer to the actual patent:<BR/>http://www.google.com/patents?vid=USPAT5664829<BR/><BR/>The bending fuse failure mode is illustrated at Figure 11 on Page 5 and described in detail beginning midway through column 7 and continuing onto column 8.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-12333997398878204042009-03-24T18:05:00.000-04:002009-03-24T18:05:00.000-04:00BB : I doubt that. If that's the case, they would ...BB : I doubt that. If that's the case, they would have received a warning that their email is nearing the quota limit.Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-67085703584732084372009-03-24T17:55:00.000-04:002009-03-24T17:55:00.000-04:00Just tried myself. Same issue. Their inbox is prob...Just tried myself. Same issue. Their inbox is probably swamped.Ronhttps://www.blogger.com/profile/16268869622833968439noreply@blogger.com