tag:blogger.com,1999:blog-4786784182488135171.post3490560861366401067..comments2023-07-21T17:26:24.127+04:00Comments on Ron George: Thomson Elite Seatpost FailureRonhttp://www.blogger.com/profile/16268869622833968439noreply@blogger.comBlogger22125tag:blogger.com,1999:blog-4786784182488135171.post-84878719910305170012009-04-17T17:13:00.000+04:002009-04-17T17:13:00.000+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-4786784182488135171.post-26792461726006221572009-03-25T20:32:00.000+04:002009-03-25T20:32:00.000+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-4786784182488135171.post-58846525657402635162009-03-25T19:42:00.000+04:002009-03-25T19:42:00.000+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'.Mark nar Atlantanoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-11838567669310198732009-03-25T18:59:00.000+04:002009-03-25T18:59:00.000+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.Mark near Atlantanoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-34005789442939941652009-03-25T18:48:00.000+04:002009-03-25T18:48:00.000+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.Philnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-54016810309102629582009-03-25T02:05:00.000+04:002009-03-25T02:05:00.000+04:00BB : I doubt that. If that's the case, they wo...BB : I doubt that. If that's the case, they would have received a warning that their email is nearing the quota limit.Ronhttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-19519931758007483492009-03-24T20:50:00.000+04:002009-03-24T20:50:00.000+04:00Do you need a 100 dollar torque wrench to calibrat...<b> Do you need a 100 dollar torque wrench to calibrate a seatpost clamp?</b><br><br>A high-quality beam-type torque wrench is about $30-$35. Of course, once you have the torque wrench you'd need to find the torque specs for a given component and that too takes a certain level of discipline and attention to detail.<br><br><b> Really? I don't think this is an over tightening issue at all.</b><br><br>Based on which of the very few facts that have been presented here? Or, is it simply the truthiness of the whole situation as someone who has emphathy for khabar bike?<br><br>Seriously, slippery slope and red herring arguments or empathy are not substitutes for facts which are still in short supply given the tenor of the original posting.Mark near Atlantanoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-68988106668465793812009-03-24T17:14:00.000+04:002009-03-24T17:14:00.000+04:00No you do not need a 100 dollar torque wrench. A ...No you do not need a 100 dollar torque wrench. A good torque wrench can be had for much less. Perhaps you do not need a torque wrench at all.<br><br>OTOH if you want to start your posts with "Forget the hype!" <br>or call it a "marketing mishap", you might want to make sure you did everything correctly before you try and cry to the masses and stick the turd in someone else's pocket.<br><br>The hype is right there on the OP's Blog. It should have said, "I broke a bike part, I am not sure how, but I sure hope the un-named manufacturer will handle things properly." Then report back later with results.<br><br>Nope! Instead a bunch of hype was created and then surrounded by a bunch of BS. Until someone with real credentials has a look at this thing, I see no other appropriate reaction other than to think this person is trying to force a manufacturers hand by trying to air some laundry that may not even be dirty.<br><br>Thomson's reputation speaks for itself. If you think it is wrong for me to side with them...Tough. Thomson has demonstrated years of great customer service, and good design. This thread and the Blog of the OP has not demonstrated anything that makes me question Thomson's reputation.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-24755757204067150972009-03-23T19:07:00.000+04:002009-03-23T19:07:00.000+04:00Why are people headbutting the owner of the seat p...Why are people headbutting the owner of the seat post? Do you need a 100 dollar torque wrench to calibrate a seatpost clamp? Really? With carbon, you can't afford to be careless really. But you can wing it with aluminum, assuming you're not out of your mind to give it 15 turns past its max limit. I don't think this is an over tightening issue at all.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-80630487472621913992009-03-23T07:57:00.000+04:002009-03-23T07:57:00.000+04:00The Profile Racing BMX freestyle and race teams ha...The Profile Racing BMX freestyle and race teams have been using Thomson seatposts on their bikes for years, and I guarantee that each of those seatposts have been involved in multiple impacts as severe as any you could imagine, particularly the freestyle team, and to my knowledge not one has ever broken.<br><br>I'm not saying it's impossible, but it's highly unlikely that the person with the broken seatpost has told us the whole story. If I had to guess I'd say overtightening as well.Gobhttp://profileracing.comnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-16793651836485212592009-03-22T22:46:00.000+04:002009-03-22T22:46:00.000+04:00Last 2 comments are SPOT ON !!Super, over high exp...Last 2 comments are SPOT ON !!<br><br>Super, over high expectations always end in disappointment - or a destructive 'blame-game'.<br><br>Ron, is everything you do 100% squeaky perfect ? - if so then fine. Otherwise follow the advice in the last 2 posts.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-79436860765008582772009-03-22T09:40:00.000+04:002009-03-22T09:40:00.000+04:00Overtightening, overtightening, overtightening. If...Overtightening, overtightening, overtightening. If the owner is legit, have him send the seatpost to Thomson and the great staff there will check it out, determine what the problem is. They will sort him out as well. Thomson has been great to me and I own a pair of Thomson masterpieces myself and an X2 and X4 Elite stem.Wilson in N.Californiahttp://www.racingmix.comnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-31024244862809429922009-03-20T19:08:00.000+04:002009-03-20T19:08:00.000+04:00This is frustrating and ridiculous!None of us know...This is frustrating and ridiculous!<br><br>None of us knows why this failed, yet some seem as if you feel betrayed that it did fail. Bike parts do not last forever, and frankly, I could care less if you or anyone else thinks this is an unintelligent response. I think it is over-the-top unintelligent to act as if Thomson committed some offense because this post broke when you have limited photographs, hearsay, conjecture, and nothing else to demonstrate that it was not abuse, neglect, or inadequate installation.<br><br>Even with a very limited amount of first hand information, we still are unsure if it was secured properly. Let's not rule out the possibility that this was UNDER-torqued or over-torqued. I do not care how many bikes a guy owns, or how many bolts he has tightened, his hands are not calibrated, and any claims that he can accurately and precisely reproduce the proper torque without adequate tools (used properly) is utter comedy!<br><br>If we post up for the world to see every time a part breaks from "JRA" and act as if the manufacturer is likely to blame, you are going to need a lot more bandwidth. I have heard a lot of JRA BS over the years...pardon me for remaining skeptical.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-80540358928272124312009-03-20T15:53:00.000+04:002009-03-20T15:53:00.000+04:00[i][b]1) Did you over tighten the seat clamp outsi...[i][b]1) Did you over tighten the seat clamp outside limiting values specified in the product sheet?[/b]<br><br>Not as far as I'm aware of.<br><br>[b]What do others think from his response?[/b][/i]<br><br>IMHO, over torque remains high on my list of contributing, if not root cause. Relative torque is just not a safe bet on any lighter weight alloy, alum or carbon components. The fall and impact was likely the coup de grace on a pre-existing condition (preloading the seat post mast well beyond spec) much the same way carbon handlebars and seat posts that are over torqued and damaged during installation will eventually fail a result from debonds in the crush zone.<br><br>If returned to Thomson (or taken to another precision machined parts manufacturer with full QA / NDI assets and MEs on staff) I'm sure they would be more than happy to conduct an objective fracture analysis that would remove all doubt as to nature of the break.Mark in Atlantanoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-3013631762229572542009-03-20T06:38:00.000+04:002009-03-20T06:38:00.000+04:00my feeling is that the failure was caused due to a...my feeling is that the failure was caused due to a number of problems as opposed to one. it all comes down like a deck of cards. in this instance it seems to be a defect, but then what you do with the product down the line adds injury after injury and finally, the darn thing just gives up.Peifernoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-42879524894661360112009-03-19T21:19:00.000+04:002009-03-19T21:19:00.000+04:00ron : it would be nice to have a closeup pic of th...ron : it would be nice to have a closeup pic of the fracture site as well.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-80081583535778037742009-03-19T18:05:00.000+04:002009-03-19T18:05:00.000+04:00Could it have been over tightened? That would be ...Could it have been over tightened? That would be my guess.Chrishttps://www.blogger.com/profile/16723257103071171990noreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-73613723306632399372009-03-19T17:08:00.000+04:002009-03-19T17:08:00.000+04:00When I saw your reference to a failure rate of 2 i...When I saw your reference to a failure rate of 2 in 1,000, I think of the doctor telling his patient that this particular operation has a mortality rate of 1% and is very safe.<br><br>"That's fine, but if you are the 1%, you are 100% dead."ksrteinhoffhttp://www.palmbeachbiketours.com/noreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-28025151330565034062009-03-19T16:53:00.000+04:002009-03-19T16:53:00.000+04:00I'd be careful making too many assumptions abo...I'd be careful making too many assumptions about what happened and why until such time as all of the facts were gathered. While it's possible that the post may have had a manufacturing defect or simply failed as purported, what's not addressed are things such as how much torque was applied to the seat clamp bolts: it's only 60 in lbs for the Elite and a mere 45 in lbs for the Masterpiece. Just looking at the break, and lacking other reports of similar failures, I'd be more inclined to suspect the torque spec for a seat clamp bolt was exceeded.Mark in Atlantanoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-36760672670971044842009-03-19T16:45:00.000+04:002009-03-19T16:45:00.000+04:00That is a funny looking fracture path. I wonder if...That is a funny looking fracture path. I wonder if after four years and a little corrosion, that a stress riser had formed and the shock of the fall caused the failure?<br><br>I see a lot of corrosion in places that have air pollution. For instance, I see much more in Dallas than in San Antonio. <br><br>Thanks for your great posts!KGS Bikes - Kevin Saundershttps://www.blogger.com/profile/10309569657468599713noreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-62709928416496850152009-03-19T16:38:00.000+04:002009-03-19T16:38:00.000+04:00what on earth is a bending fuse. sounds like a cou...what on earth is a bending fuse. sounds like a cousin of electrical fuse. to think all that's under my bottom....Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4786784182488135171.post-26023597874988154662009-03-19T08:39:00.000+04:002009-03-19T08:39:00.000+04:00Did he follow up with Thomson? What did they have...Did he follow up with Thomson? What did they have to say about it?<br><br>Also, as the owner of some components that I have seen counterfeited (like Zipp), you can't rule that out. Are we all 100% sure that this post was genuine and passed factory spec?<br><br>I expect to hear follow-up about this one, I'm very surprised.Matt in Denvernoreply@blogger.com