Page 1 of 3 123 LastLast
Results 1 to 50 of 142
  1. #1
    mtbr member
    Reputation:
    Join Date
    Mar 2004
    Posts
    826

    Thomson Seatpost Broke today

    I'm OK, which is the main thing. Seriously, if I had not been riding on smooth concrete, this would have been a compete disaster. Added help was that I have a small Cannondale seatbag for a spare tube under my seat with small velcro loop that goes around the post in addition to the seat rails. That's the only thing that saved me from an aluminun colonoscopy. I have 5 Thomson seatposts and never had an issue with any of them till today. Across those posts I have over 100,000 care free miles. Owned this particular post 10 months and about 2000 miles. It's a Thomson Setback 31.6 410mm I have been using in Cannondale Caffeine framesets. The post has never been dropped, wrecked, knock over or even put in a repair stand.

    Frankly I did not think this was possible because I read that the bolts are supposed to break before the seatpost. I have not even heard of a Thomson failure before.






  2. #2
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    That really sucks. Call them and they'll take care of you.

  3. #3
    pedal pusher
    Reputation: f3rg's Avatar
    Join Date
    Aug 2007
    Posts
    2,713
    Wow, that sucks. Although, not everyone can brag about breaking a Thomson, so at least you have that much going for you.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Feb 2009
    Posts
    51
    I'm guessing they will be very concerned, send you a new one, and ask for the broken one for analysis

  5. #5
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    Ever hit a garage?

  6. #6
    Ride Instigator
    Reputation: Ricko's Avatar
    Join Date
    Jan 2004
    Posts
    3,221
    Quote Originally Posted by Jerk_Chicken
    Ever hit a garage?
    'Zakly what I was thinking .

  7. #7
    mtbr member
    Reputation:
    Join Date
    Mar 2004
    Posts
    826
    Quote Originally Posted by Jerk_Chicken
    Ever hit a garage?
    Nope. Don't even own a roof rack. Don't even own a garage.

    Had to ride 18 miles home standing. That gets a little old after awhile. But not too bad. The weather was nice and I had the wind at my back.

  8. #8
    Ride Instigator
    Reputation: Ricko's Avatar
    Join Date
    Jan 2004
    Posts
    3,221
    Quote Originally Posted by apacherider
    Nope. Don't even own a roof rack. Don't even own a garage.

    Had to ride 18 miles home standing. That gets a little old after awhile. But not too bad. The weather was nice and I had the wind at my back.
    Wow, that is just nuts...looks like something absolutely catastrophic happened there. 18mi...no cell phone? I called the wife today to come and rescue me with the truck because I flatted on the road bike a 2nd time 15 miles from home, grrr.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Nov 2008
    Posts
    92
    Is this even common for any kind of kind of seat post, including non name brands? Just thinking about the potential injury from taking that up the rear is disturbing.

  10. #10
    Now with 10% more!
    Reputation: Da Dook's Avatar
    Join Date
    Oct 2007
    Posts
    407
    Now I've seen it all.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Mar 2007
    Posts
    88
    Maybe it was a manufacturing defect that took 2k miles to finally break?

  12. #12
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Any chance of getting a macro close up of the cross section on both ends? I'd love to see a close up of the damage.

    I had a post fail on me on the trainer. But the funny part was that I was on the trainer b/c I had a broken collar bone so I couldn't use my arm/ride outside.

    When the post broke, I collapsed to the floor banging my arm/shoulder into pretty much everything, that really hurt. But kinda funny now....

  13. #13
    mtbr member
    Reputation:
    Join Date
    Mar 2004
    Posts
    826
    Quote Originally Posted by civil
    Any chance of getting a macro close up of the cross section on both ends? I'd love to see a close up of the damage.



    That's about as good a photo as I can get with my crummy camera. I know nothing about metal or fatigue. The front side is the clean break side, the rear is the jagged side. From what I understand, the seatpost has an elliptical build to it with more material on the front/back rather than the sides. Does it look like the rear end lacks some material or is that just a result of the deforming when it broke?

    In the photo below, see all the little teeny tiny fractures? They are on the rear facing side of the seat post. I don't know if they occured over time and I did not notice or if they occured as a result of the post at the moment it broke.


  14. #14
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Well, I'll make some generalizations here, but here's a quick guess..

    Judging by the pic (I can't really tell b/c I can't see enough detail), it looks like a crack may have initiated here (arrow) and slowly propagated outward towards the line. Every loading cycle would cause the crack to propagate further. (front side of post in Tension and back side in Compression, cracks propagated through tension side due to opening and closing of crack from loading cycles)

    The surface looks smooth up until the line, indicating the area that the fatigue crack propagated through.

    To the right of the line, the remaining material wasn't strong enough to hold the stress and a shear failure (rough surface indicates this) occured, which would have deformed the rear end of the surface. The little wrinkles on the back of the post could be some straining due to the final shearing.

    Do I'll chalk it up to a fatigue failure due to some stress riser/imperfection.

    *edit* Glad you were OK
    Attached Images Attached Images

  15. #15
    Old Skool Dirt Bag
    Reputation:
    Join Date
    Oct 2004
    Posts
    84
    Geez that scares the crap out of me, and its a 31.6mm post too!

    I guess I will be examining my 31.6mm straight post tonight real careful. From the lack of shiny rub points in the fracture zone it looks like it happened more or less all at once, sure looks thin on the relieved side.

    Thanks for sharing with us, you may have saved someone elses rectum if they have a similar post issue. Glad you weren't hurt, it could have been real nasty.

    Kinda makes me rethink the weight savings from these seat posts, for the small amount of weight a straight gauge tube sure sounds safer.

  16. #16
    Old man on a bike
    Reputation: Bikinfoolferlife's Avatar
    Join Date
    Feb 2004
    Posts
    12,382
    Can't say I've seen a report of anything like the OP experienced FWIW. Everyone's gonna have a problem here and there. I think you can usually rely on Thomson's products more than many others in any case...
    "...the people get the government they deserve..."
    suum quique

  17. #17
    pedal pusher
    Reputation: f3rg's Avatar
    Join Date
    Aug 2007
    Posts
    2,713
    OP, how much do you weigh?




    /hoping it's twice as much as I weigh

  18. #18
    Bicyclochondriac.
    Reputation:
    Join Date
    Jan 2004
    Posts
    13,387
    Quote Originally Posted by RookieBeotch
    Is this even common for any kind of kind of seat post, including non name brands? Just thinking about the potential injury from taking that up the rear is disturbing.
    I've broken a post, and I don't think there is a huge danger of getting sodomized by the post. When it breaks you have the seat between your a$$ and the top of the post. Now, if you forget about it as you ride on, that's a different story.

  19. #19
    It's about showing up.
    Reputation: Berkeley Mike's Avatar
    Join Date
    Jan 2004
    Posts
    12,731

    Thompson will want to see this.

    I'd send it to them for science alone. Now whether you want to see if they will cover it, that is another issue but I don't sense that you feel they are obliged

  20. #20
    mtbr member
    Reputation:
    Join Date
    Jun 2007
    Posts
    247
    Also looks to me like a MFR issue.
    Just goes to show ALL parts need a regular check.

    Oh, I would not have expected it to fail at that point. Should have been more flex further down the shaft. I would be very sure this was a fault from production.

  21. #21
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    61
    I ride nothing but Thomson, that blows my mind I thought they were indestructable. Glad to hear your ok, but 18 miles standing up...Your an ANIMAL!!!!

  22. #22
    mtbr member
    Reputation: Spindelatron's Avatar
    Join Date
    Aug 2006
    Posts
    906
    was anything sharp on your saddle bag rubbing the seatpost?

  23. #23
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31

    Caution;  Merge;  Workers Ahead! Thanks Apacherider

    Apacherider,

    I noted a similar incident on a Thomson Elite seatpost on my blog. Read it here.

    Seems like a good way to connect...

    As you will see in my writeup and the attached pictures, I did the best I could to collect all relevant details from the rider as to how he used it. Given his information (and trusting it), I don't see how the bolting ears could have just snapped off like that.

    In your case, again...I can't see how 2000 miles of riding will cause the post to crack at that spot.

    What's your weight? And did you follow all installation instructions in the manual, like torque settings on the clamps? Did the post also take a fall anytime you remember, and like someone asked before me, do you remember having put anything sharp in your saddlebag that may have marked up the post? (I do not see how that can happen when something sharp is inside your bag but for the sake of information collection, let's have it all from you...)


    Thanks...

    Ron
    Cozy Beehive Bike Blog

  24. #24
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    I noted a similar incident on a Thomson Elite seatpost on my blog. Read it here.
    This failure is not similar.

  25. #25
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31

    Anodized Finish ?

    Quote Originally Posted by Jerk_Chicken
    This failure is not similar.
    No, no one said its a similar failure. I said the incident is similar as in it involves a Thomson post.

    Failures with Thomson are pretty rare given their reputation among cyclists for making strong components. But these two incidents occurred not very far apart from each other (both this year). Marketing materials from Thomson claim "over 40% on ultimate strength test than the strongest production seat posts on the market" and the presence of a unique 'bending fuse' to prevent catastrophic failure. In my writeup, we determined that this fuse could be nothing more but a fancy term for the cushion of safety achieved by the elliptical bore, specifically in the lateral sections of the post where it is thinnest, as opposed to the bolt ear locations which are thickest. Due to this, the sides of the post folds before the fore and aft sections having the bolt ears do, offering some degree of protection to the cyclist from a fall.

    What could be interesting about the pictures provided by apacherider is that the ideas behind the "bend, not break" philosophy and the elliptical bore may be insignificant in reality...because as Civil pointed out here before, the crack originated on the thicker section (pointed by red arrow). But that's needs confirming through a fracture analysis.

    Just one final thought. The black finish is beautiful. It is chemically polished and then anodized. But my mind keeps asking whether this treatment makes the post any more susceptible for failure. Jobst Brandt, mechanical engineer and author of "The Bicyle Wheel", didn't favor anodized rims, advising that when rims are anodized, a thin layer of porus, Al oxide is the result and the problem is that this oxide material is extremely hard but brittle. This makes the rim more susceptible to cracking and fatigue failure. This is actually a well known issue in materials circles. As Al bends elastically, the anodized surface cracks and the crack grows into the body of the Al. Anodized aluminum only worsens the fatigue limitations of Al. You can't bend anodized Al significantly without cracking it. The cracks that develop on the coating are stress risers and potential sources for fatigue failure in the substrate metal.

    Could the same be said for this seatpost, which also has an anodized finish? My feeling is that anodizing is a bad choice for a part made to take bending.
    Last edited by Cozy.Beehive; 04-12-2009 at 02:00 AM.

  26. #26
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    No, no one said its a similar failure. I said the incident is similar as in it involves a Thomson post.

    Failures with Thomson are pretty rare given their reputation among cyclists for making strong components. But these two incidents occurred not very far apart from each other (both this year). Marketing materials from Thomson claim "over 40% on ultimate strength test than the strongest production seat posts on the market" and the presence of a unique 'bending fuse' to prevent catastrophic failure. In my writeup, we determined that this fuse could be nothing more but a fancy term for the cushion of safety achieved by the elliptical bore, specifically in the lateral sections of the post where it is thinnest, as opposed to the bolt ear locations which are thickest. Due to this, the sides of the post folds before the fore and aft sections having the bolt ears do, offering some degree of protection to the cyclist from a fall.

    What could be interesting about the pictures provided by apacherider is that the ideas behind the "bend, not break" philosophy and the elliptical bore may be insignificant in reality...because as Civil pointed out here before, the crack originated on the thicker section (pointed by red arrow). But that's needs confirming through a fracture analysis.

    Just one final thought. The black finish is beautiful. It is chemically polished and then anodized. But my mind keeps asking whether this treatment makes the post any more susceptible for failure. Jobst Brandt, mechanical engineer and author of "The Bicyle Wheel", didn't favor anodized rims, advising that when rims are anodized, a thin layer of porus, Al oxide is the result and the problem is that this oxide material is extremely hard but brittle. This makes the rim more susceptible to cracking and fatigue failure. This is actually a well known issue in materials circles. As Al bends elastically, the anodized surface cracks and the crack grows into the body of the Al. Anodized aluminum only worsens the fatigue limitations of Al. You can't bend anodized Al significantly without cracking it.

    Could the same be said for this seatpost, which also has an anodized finish? My feeling is that anodizing is a bad choice for a part made to take bending.
    Your theory doesn't take into account that the moment Al is exposed to air, its surface oxidizes anyway. It's true, it's not controlled oxidation as Anodizing is, but there is a thin layer (thinner than anodization) that is actually protective.

    You obviously haven't seen plenty of non-anodized parts bent that exhibit cracks like that.

    Additionally, you're relating two things incorrectly. The cracks are on the back, and from shifting and bending as the last piece of the post was was still attached there. Some of your words here, and on your site, are looking like Alex Jones conspiracy theories, just jumping around for conclusions. And we get it. You're looking to get people to visit your site. Big deal. The post cracked, either from impact in a crash while riding, rider, anything, then the crack worked its way backwards and tore off. We can have a multitude of theories here, in and against the OP's favor, but there's also a history of Thomson's posts as having a low rate of failure and outlasting bikes.

  27. #27
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31
    Quote Originally Posted by Jerk_Chicken
    Your theory doesn't take into account that the moment Al is exposed to air, its surface oxidizes anyway. It's true, it's not controlled oxidation as Anodizing is, but there is a thin layer (thinner than anodization) that is actually protective.

    You obviously haven't seen plenty of non-anodized parts bent that exhibit cracks like that.

    Additionally, you're relating two things incorrectly. The cracks are on the back, and from shifting and bending as the last piece of the post was was still attached there. Some of your words here, and on your site, are looking like Alex Jones conspiracy theories, just jumping around for conclusions. And we get it. You're looking to get people to visit your site. Big deal. The post cracked, either from impact in a crash while riding, rider, anything, then the crack worked its way backwards and tore off. We can have a multitude of theories here, in and against the OP's favor, but there's also a history of Thomson's posts as having a low rate of failure and outlasting bikes.


    For a successful surface preparation before anodizing, an AL surface is chemically cleaned off all oxides and this is a basic requirement for the process. [See : AL and AL Alloys, ASM Handbook, Joseph Davis] I'm not sure what other intermediate oxide you're talking about. Please clarify.

    Anodizing significantly decreases the fatigue strength of Al alloys. I based my judgment off that fact. I acknowledged the reputation of Thomson components already, as you can see. Infact, I'm a Thomson seatpost user and I wouldn't install one on my bike if I didn't think it was good. But again, no design is perfect. Not sure why you're so angry but you need to calm down. Again, if you actually read my blog post, you'd see that I made an effort to collect facts and discuss what might have caused the failure, since I understand a lot of folks may be using this product. You're quick to jump to narrow judgments.

    Way to inform others about your knowledge though....

  28. #28
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    For a successful surface preparation before anodizing, an AL surface is chemically cleaned off all oxides and this is a basic requirement for the process. [See : AL and AL Alloys, ASM Handbook, Joseph Davis] I'm not sure what other intermediate oxide you're talking about. Please clarify.
    Way to inform others about your knowledge though....
    I'm displaying the contrast between the two parts of your post. You either don't read very well (comparing my post, and your first paragraph), or you don't want to read well and want to keep referring to your big book 'o knowledge.

    And anger? Where do you gather that from? This is a message board and this is entertainment. You just don't seem to like when opinions counter yours because you have a book. You and Alex Jones should pair up.

  29. #29
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31
    Quote Originally Posted by Jerk_Chicken
    I'm displaying the contrast between the two parts of your post. You either don't read very well (comparing my post, and your first paragraph), or you don't want to read well and want to keep referring to your big book 'o knowledge.

    And anger? Where do you gather that from? This is a message board and this is entertainment. You just don't seem to like when opinions counter yours because you have a book. You and Alex Jones should pair up.

    Ok I will pair up if I wish. Tell me something. What oxide were you talking about? Thought you were going to reply to that. I acknowledge my mistake... I meant to say the wall thickness of the post body are thinnest at the sides, when you look from the bottom. It is more thicker to the front and rear.
    Last edited by Cozy.Beehive; 04-12-2009 at 03:39 AM.

  30. #30
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    The answer is in post 26.

  31. #31
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31
    Quote Originally Posted by Jerk_Chicken
    The answer is in post 26.
    I did see that and replied right away that before anodizing, the industry standard is to chemically clean the surface off any pre-existing oxides to ensure a good anodized finish through electrolysis, which you didn't bother replying to.

  32. #32
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,466
    I did see that and replied right away that before anodizing, the industry standard is to chemically clean the surface off any pre-existing oxides to ensure a good anodized finish through electrolysis, which you didn't bother replying to.
    Then I can't help you.

    Also noted is altering your posts after I reply to them.

  33. #33
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31
    Quote Originally Posted by apacherider
    I'm OK, which is the main thing. Seriously, if I had not been riding on smooth concrete, this would have been a compete disaster. Added help was that I have a small Cannondale seatbag for a spare tube under my seat with small velcro loop that goes around the post in addition to the seat rails. That's the only thing that saved me from an aluminun colonoscopy. I have 5 Thomson seatposts and never had an issue with any of them till today. Across those posts I have over 100,000 care free miles. Owned this particular post 10 months and about 2000 miles. It's a Thomson Setback 31.6 410mm I have been using in Cannondale Caffeine framesets. The post has never been dropped, wrecked, knock over or even put in a repair stand.

    Frankly I did not think this was possible because I read that the bolts are supposed to break before the seatpost. I have not even heard of a Thomson failure before.

    Apache, no where did I come across a statement that their bolts are supposed to break before the seatpost. I would expect something like this to be counterproductive to safety. If the bolts break, the saddle comes off and there goes the rider.

    From marketing materials, this is said : "Under severe impact the Thomson seatpost would bend slightly and allows the rider to come to a safe stop or finish the ride. The ride could continue."

    Putting this alongside what you actually experienced, things do not add up.

  34. #34
    mtbr member
    Reputation:
    Join Date
    Mar 2004
    Posts
    826
    Quote Originally Posted by Cozy.Beehive
    Apacherider,

    I noted a similar incident on a Thomson Elite seatpost on my blog. Read it here.

    Seems like a good way to connect...

    As you will see in my writeup and the attached pictures, I did the best I could to collect all relevant details from the rider as to how he used it. Given his information (and trusting it), I don't see how the bolting ears could have just snapped off like that.

    In your case, again...I can't see how 2000 miles of riding will cause the post to crack at that spot.

    What's your weight? And did you follow all installation instructions in the manual, like torque settings on the clamps? Did the post also take a fall anytime you remember, and like someone asked before me, do you remember having put anything sharp in your saddlebag that may have marked up the post? (I do not see how that can happen when something sharp is inside your bag but for the sake of information collection, let's have it all from you...)


    Thanks...

    Ron
    Cozy Beehive Bike Blog
    Read your link. Wow! You really got in depth there.

    To answer your questions, I weigh anywhere from 190-200lbs depending on the time of year. I only ride XC, mostly fire roads, XC trails and pavement. That post has never been in a wreck, collision, never hit a tree, post or pole. Never even been in a repair stand.

    Installation instructions were followed to the letter. Not so much for the seat post's sake but because I have an expensive Fizik saddle and do not want to bugger it up. Like I said in my post above, it is a 31.6mm 410, which fits the Cannondale Caffeine. I was using it in a 2009 Cannondale 29er 2, that I have only owned since early March. I have been over that bike with a fine tooth comb a dozen times since I bought it. Here is the top tube/seattube junction:



    Brand new bike for the most part. Maybe 800 miles on the frame, only 50 of which were on dirt.

    Here are a few more photos with the hardware removed. Gives one a better sense of where it broke:

    Back:

    Front:


    Also included a photo of the saddlebag I use, since you asked about it.


    Must just be a complete fluke that it broke. Like I said, I have used Thomson seatposts for a decade, 100,000 miles worth. I'm one of their biggest fans. Just left me scratching my head as to how it broke. I average about 800-1000 miles a month riding, so this was a very low mileage part for me.

    I'll get in contact with them on Monday and see about a warranty replacement. Still have the cloth bag it came in too!

  35. #35
    Bicyclochondriac.
    Reputation:
    Join Date
    Jan 2004
    Posts
    13,387
    This is not that big of a mystery. Things break. Even high quality things that almost never break sometimes break. It's like the lottery: You can pretty much count on NOT winning with near certainty, and it is a huge surprise when you do, but it's not "how could this possibly happen?"

    I would say that after 100,000 miles, it is not that outlandish that you could see some unlikely event, such as one of these failing. That's what, 5,000 20-miles rides? A 20 mile ride every day for almost 14 years?

    After 2,000 miles (100 20-mile rides, or roughly three 20-milers per week for the ten months you've had it) I find it unlikely that you can say for certain that there was never any damage that happened to the post, or some blow that could have started the crack. Not saying you did it, but I can't see how that could possibly be ruled out.

  36. #36
    mtbr member
    Reputation:
    Join Date
    Mar 2004
    Posts
    826
    Quote Originally Posted by kapusta
    I find it unlikely that you can say for certain that there was never any damage that happened to the post, or some blow that could have started the crack. Not saying you did it, but I can't see how that could possibly be ruled out.
    Just to rule that out, I don't have so much as a scratch of any kind on my saddle. It's a Fizik with 5000 miles on it. Like I have said, no damage to the seatpost. Besides, that failure is so far up underneath the saddle nose(on the front) and basically under the rails(on the rear), that I don't think anything could contact it. It. Just. Broke.


  37. #37
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by kapusta
    This is not that big of a mystery. Things break.
    Very true, but the question is why. Riding mishap? Installation error? Manufacturing defect?

    Quote Originally Posted by kapusta
    I find it unlikely that you can say for certain that there was never any damage that happened to the post, or some blow that could have started the crack. Not saying you did it, but I can't see how that could possibly be ruled out.
    While it may not be certain, it's highly unlikely that something would have hit that area while riding. It's very high on the post, almost hidden by the bolt, and shielded by his legs. For an item small enough to hit that exact spot, with enough force to damage the post, while dodging all the obstacles in the way is pretty low on the probability scale. Not impossible, but unlikely.

    Probably not an installation error, that would have failed the post at the seat-tube clamp or post bolt.

    A much more probable solution was that there was some kind of stress riser there from the manufacturing process.

    Or it was damaged in shipping and handling. That being said, for it not to be noticed during installation would mean a very small damaged area which would require a very large force by a very small object. Possibly your room-mate with a hammer and nail punch. Do you have any enemies that would benefit from your passing?
    Last edited by civil; 04-12-2009 at 09:58 AM.

  38. #38
    Bicyclochondriac.
    Reputation:
    Join Date
    Jan 2004
    Posts
    13,387
    Quote Originally Posted by civil
    Possibly your room-mate with a hammer and nail punch.
    I was thinking pissed off ex.

  39. #39
    mtbr member
    Reputation:
    Join Date
    Nov 2008
    Posts
    92
    Regardless, I still want a Thomson post for my bike.

  40. #40
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by kapusta
    I was thinking pissed off ex.
    Even more likely

    Quote Originally Posted by RookieBeotch
    Regardless, I still want a Thomson post for my bike.
    PM apacherider, I think he has one for cheap.

  41. #41
    mtbr member
    Reputation:
    Join Date
    Apr 2009
    Posts
    31
    Quote Originally Posted by apacherider
    Read your link. Wow! You really got in depth there.

    To answer your questions, I weigh anywhere from 190-200lbs depending on the time of year. I only ride XC, mostly fire roads, XC trails and pavement. That post has never been in a wreck, collision, never hit a tree, post or pole. Never even been in a repair stand.

    Installation instructions were followed to the letter. Not so much for the seat post's sake but because I have an expensive Fizik saddle and do not want to bugger it up. Like I said in my post above, it is a 31.6mm 410, which fits the Cannondale Caffeine. I was using it in a 2009 Cannondale 29er 2, that I have only owned since early March. I have been over that bike with a fine tooth comb a dozen times since I bought it.

    Must just be a complete fluke that it broke. Like I said, I have used Thomson seatposts for a decade, 100,000 miles worth. I'm one of their biggest fans. Just left me scratching my head as to how it broke. I average about 800-1000 miles a month riding, so this was a very low mileage part for me.

    I'll get in contact with them on Monday and see about a warranty replacement. Still have the cloth bag it came in too!

    Sounds good. Let us know how the conversation goes. The last time I tried emailing them on this topic, their email wasn't even working. I figured concerns about the reliability of the seatpost must have flooded their inbox, but in reality...a lady who worked there told me that they were having some work done to their telephone network. Either way, if you're going to call them based on the number on their website, its going to go to a call center...the people who work there may have limited knowledge about technical issues. Just a heads up.

  42. #42
    rides with camera
    Reputation: sherijumper's Avatar
    Join Date
    Feb 2007
    Posts
    895
    This has been an interesting read , I run thomson posts on two of my bikes and no problems thus far ( like 99 % of us) . As Kapusta said " it`s like winning the lottery" I think that is a pretty good point . Thomson posts , stems are some of the strongest in the industry . I think this thread is just another good reason to inspect our equipment when mantaining it . I know you won`t catch every hairline crack, but you never know what you might find .
    Fu(k cancer

    thelonebiker.com

  43. #43
    discombobulated SuperModerator
    Reputation:
    Join Date
    Jun 2005
    Posts
    3,214
    Quote Originally Posted by Jerk_Chicken
    Your theory doesn't take into account that the moment Al is exposed to air, its surface oxidizes anyway. It's true, it's not controlled oxidation as Anodizing is, but there is a thin layer (thinner than anodization) that is actually protective.

    You obviously haven't seen plenty of non-anodized parts bent that exhibit cracks like that.

    Additionally, you're relating two things incorrectly. The cracks are on the back, and from shifting and bending as the last piece of the post was was still attached there. Some of your words here, and on your site, are looking like Alex Jones conspiracy theories, just jumping around for conclusions. And we get it. You're looking to get people to visit your site. Big deal. The post cracked, either from impact in a crash while riding, rider, anything, then the crack worked its way backwards and tore off. We can have a multitude of theories here, in and against the OP's favor, but there's also a history of Thomson's posts as having a low rate of failure and outlasting bikes.
    The answer is in post 26..I looked, and there it is!
    I think JC is talking about a non-anodized post becoming "anodized" (IE oxidized) anyway when exposed to the elements. Thereby nullifying to some extent the claim that anodizing is worse than non anodized!
    By Jove!
    CDT

  44. #44
    mtbr member
    Reputation: sdf1968's Avatar
    Join Date
    Mar 2007
    Posts
    178
    I had a seatpost break once when I first started to ride. It was not a Thomson so I am not as talented as apacherider. I was on a really fast downhill and I just jumped off a small lip and when I landed all I heard was PING and I was on the ground looking at the sky. Had a round bruise in the middle of my chest so I think there is less chance of rectal damage and more chance of torso damage. I had to ride 7 miles back standing up and I thought that was bad....18 miles!

  45. #45
    mtbr member
    Reputation: wormvine's Avatar
    Join Date
    Oct 2005
    Posts
    3,160
    I guess we all should get thermal cams then. Easy to spot a crack with a thermal cam!

  46. #46
    mtbr member
    Reputation: wormvine's Avatar
    Join Date
    Oct 2005
    Posts
    3,160
    Quote Originally Posted by CdaleTony
    The answer is in post 26..I looked, and there it is!
    I think JC is talking about a non-anodized post becoming "anodized" (IE oxidized) anyway when exposed to the elements. Thereby nullifying to some extent the claim that anodizing is worse than non anodized!
    By Jove!
    CDT
    How does it nullify it? Just cause nicks of exposed aluminum oxidized slightly doesn't mean it has the same affect that a large scale chemical anodization does. It raises a question that needs to be researched but far from nullifies the original statement.

  47. #47
    TNC
    TNC is offline
    noMAD man
    Reputation: TNC's Avatar
    Join Date
    Jan 2004
    Posts
    12,059
    Yeah, this has been interesting. Thomson makes some nice, tough seatposts, but as already stated, nothing is indestructible. The only Thomson seatpost issue I've ever seen is the "crimping" that can occur, usually in cases of overtighening the post collar at the seat tube. Seatposts shouldn't be overtightened, but a Thomson is one such post that can develop a "waist" at the point of normal seating height. Not that the Thomson is the only one that can have this occur. Even then, however, I've never seen one break at that "waisted" spot on the post. Usually the only evidence of this is when the post won't stay put exactly where you tighten it.

  48. #48
    Bike Dork
    Reputation: themanmonkey's Avatar
    Join Date
    Nov 2005
    Posts
    1,365
    OK from an industry standpoint Thompson stuff is great and has one of the best reps around, but they're far from perfect. I've installed a few hundred posts and stems and seen a good number of broken and poorly-machined parts. Of course I don't know of a post maker I haven't seen break. Parts breakages are part of the game and it's so much better than 10-20 years ago. I generally tell folks that if you have a lightweight post, stem, or bar think about replacing them after 10,000 miles.

    Personally I have a Control Tech, a couple American Classic, and various Campy posts that are well over a decade old and 10,000 miles was a long time ago on all of them. I also have a superlight ti McMahon post that supposedly "always broke" still running strong. I know I'm on borrowed time on each of these posts and I just keep that in mind when I ride. It's not about if a part will break, it's about when it'll break.

    Again, Thompson parts are some of the most reliable parts in the industry, but they won't last forever.

  49. #49
    ♥ ς╥33£
    Reputation: longcat's Avatar
    Join Date
    Apr 2008
    Posts
    488
    Its a brittle fracture, I guess all these common aluminum alloys breaks brittle more or less. What could have caused it? I dont know, anything from bad hair day to alloying % being out of specs to microscopic pores to bad heat treatment or overheating while being machined etc etc etc probably 1000s of possible resons for this failure. Could be anything really
    Quote Originally Posted by Curmy
    Carbon is a fad.
    Quote Originally Posted by robicycle
    Just lube your ass with asscream and ride for how long you want.

  50. #50
    mtbr member
    Reputation:
    Join Date
    Feb 2008
    Posts
    1,058
    Quote Originally Posted by longcat
    Its a brittle fracture, .......... Could be anything really
    Did you actually read any of the posts?

    There are a couple of educated guesses with some valid reasoning behind them which point to a specific answer.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •