Tern Link D8 frame shearing in two

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:20 pm


April 5, 2014 - 12:22am
edwinic



Country: Philippines

"Looks like Tern used the SGM factory....I will get more pics tomorrow." - this is at best is a guess, a possibility but a long shot. I tell you a secret, in the Philippines, if a lesser company works for a Bigger company like SGM/Tern, the words will be out on the street officially or through the backdoor.

Pursue your guess, its good for everybody, for the bike industry. Work with evidence. Speculate but separate that from reality.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:23 pm


April 5, 2014 - 8:42am
bikerrrguy

Country: USA


Do the below look similar? I saw others some time ago....but it is really hard to find on facebook. It took me about 30 min to find these.

edwinic wrote:

"Looks like Tern used the SGM factory....I will get more pics tomorrow." - this is at best is a guess, a possibility but a long shot.






SGM Storm 3





Thanks,

Yan

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:24 pm


April 5, 2014 - 9:17am
orbit

Country: UK


That looks even worse than the Tern breakage. It looks like the weld has not even worked, and the frame looks like fag paper.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:24 pm


April 5, 2014 - 9:26am
bikerrrguy

Country: USA



Keith C. Johns wrote:

Dr. Yan:

OK. But really, it seems to me that the CEO of a competitor bike company should have better things to do than try to disrupt the forum of its competitor. It is underhanded, even if you think you have inside knowlege and a few facts on your side. On Dahon's forum, when Josh ran it, he always spoke highly and supportingly of other bike companies even though they were competitors. I recall specifically a few comments he made about Bike Friday which were very upbeat. His attitude was that ALL bike companies are making the world better by getting people out of cars and into a more healthful lifestyle, and anything he could do to get people to buy bikes, even the competitors' bikes, was worthy. I am not making this up. So your charaterization of Josh is out of phase with everything I do know about him. The suggestion that he has criminal intent and is willing to let people suffer rather than fix a design flaw just does not match the man I have observed for at least twelve years. I want to suggest that you ought to consult your lawyers before you make libelous or slanderous comments on the forum of your competitor.

I have some interest in your product line, as I do of all folding bikes, but I want to suggest that if you think you will succeed better by knocking down the competition, that is not the way to go. It makes your cause look less than honorable. You ought to take Josh's lead and support the brotherhood of all bike manufacturers.

If Tern is making a bad design, it will eventually be impossible to hide this fact from the public--why risk the taint that clings to any person who slanders his opponent? Let the chips fall where they may. Stay above the fray.

But I want to say that I disagree with your conclusions about Tern. Call me naive if you will, I believe these guys are better than you are suggesting they are. And I really would be surprised to hear that they don't have any engineers on their team--just a bunch of marketing guys: how would they come up with so many unique bikes? I can't accept the suggestion that they stole all of them from Dahon. I recommend you stick to facts you can prove, and post them on your own forum too. But again, I don't think you will win converts by bad-mouthing your competition.



Keith,




I learned of these problems about two months ago. My wife told me not to get involved, let it play. We both understood Tern was in serious trouble at the time. Since that time I have seen:

1. nothing happen from Tern,

2. More frames break ( 3 or 4 )

3. no refunds or compensation to customers

4. claims from Josh that this is probabilistically normal ( my field is probability theory ) and I know his import numbers are false.

After this I understaood Tern was dead. My wife reiterated do not get involved. Then Thor started posting some nonsense on this forum, so I called him and told him to stop. I shared all information with him. At the end of the conversation I believe he knew Tern was finished.

Tern is finsihed anyway, why would I risk myself to enter this thread? Once the forum went private I felt it is my job to get the truth out. I contacted Lynette Carpiet from Bicycle Retailer right away. FYI she was not surprised to hear about Josh's troubles. I also tried to login to the forum with the name bikerguy, however it was nearly impossible to do so. It took me well over 15 minutes to get in. I changed my username to bikerrguy then bikerrrguy to make sure that was not the fault.

FYI I am a full time professor at a wonderful College, and my business is fiscally stromg. I need this headache as much as all of you! No one wants to be here to discuss this matter!

Thanks,

Yan

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:24 pm


April 5, 2014 - 10:48am
vavavoom

Country: Greece



Yan,

The pictures you are attaching look to me completely different from all tern failures. I am no technical expert and I have nothing to do with the bike industry, but the weld quality seems lower. The distance from the welds to the tube rim is uneven, there is a crack on the tube, the composition of the welds looks granular rather than the one on terns which is smoother, there are probable signs of corrosion on many different places (unless it is a photo artifact). Anyway, as I already said, I am no expert and this is just a photo.

Also, it is a photo from a different company (which you guess has something to do with Tern) . Should we start posting all kinds of failures on this thread? Dahons? Bromptons?

What are you trying to prove? That somehow this has to do with the tern failures? I fail to see your point.

And....Tern is...finished? Wow, this escalated quickly!!!

Look, this thread is already full of speculations. Also, all the owners of the broken bikes are frustrated and wounded and the last thing they need right now is more speculations. Additionally, some of us own this model and are REALLY, not theoreticaly concerned. And there you go with your guesstimates. Can you prove your theory? If you can, it would be really helpful. If you can't, don't expect to be taken seriously. Simple math.

If you take my case, I woud probably look like THE greatest schmuck on this thread, because I stated my trust in this company after the first failure and then went on to buy a Link D8. But I am far from dissapointed, I am just being patient.

You are entitled to your own opinion, but don't present it as a fact, unless you have proof to do so. You know better than me that your photo is no proof.

BTW, you could have just stated your cycling-related credentials. Your chess, maths, teaching, yoga and "healing" skills are off topic.


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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:25 pm


April 5, 2014 - 11:17am
edwinic




Country: Philippines


Mr Yan, at best your picture has proved that SGM breaked. It does not prove your gut-feeling that Tern used SGM factory. If you have better than that bring it out on the table. The suspense is killing (at least) Me.
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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:25 pm



quote
reply

April 5, 2014 - 12:53pm
bikerrrguy

Country: USA


edwinic wrote:

Mr Yan, at best your picture has proved that SGM breaked. It does not prove your gut-feeling that Tern used SGM factory. If you have better than that bring it out on the table. The suspense is killing (at least) Me
.

This is not a gut feeling. Given the probability of a bicycle frame breaking is amazingly low ( give it any estimate you want ). The probability of Tern's 6 known frame failures being independant ( different factory ) of SGM's 5+ listed on facebook is essestailly an impossible event. I am essentailly doing a statistical hypothesis test. My conclusion on this matter are true with HIGH probability.



I believe you can do your own hypothesis test on Excel.



Thanks,

Yan

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:26 pm


April 5, 2014 - 1:03pm
bikerrrguy

Country: USA


vavavoom wrote:

Yan,

The pictures you are attaching look to me completely different from all tern failures. I am no technical expert and I have nothing to do with the bike industry, but the weld quality seems lower. The distance from the welds to the tube rim is uneven, there is a crack on the tube, the composition of the welds looks granular rather than the one on terns which is smoother, there are probable signs of corrosion on many different places (unless it is a photo artifact). Anyway, as I already said, I am no expert and this is just a photo.

Also, it is a photo from a different company (which you guess has something to do with Tern) . Should we start posting all kinds of failures on this thread? Dahons? Bromptons?

What are you trying to prove? That somehow this has to do with the tern failures? I fail to see your point.

And....Tern is...finished? Wow, this escalated quickly!!!

Look, this thread is already full of speculations. Also, all the owners of the broken bikes are frustrated and wounded and the last thing they need right now is more speculations. Additionally, some of us own this model and are REALLY, not theoreticaly concerned. And there you go with your guesstimates. Can you prove your theory? If you can, it would be really helpful. If you can't, don't expect to be taken seriously. Simple math.

If you take my case, I woud probably look like THE greatest schmuck on this thread, because I stated my trust in this company after the first failure and then went on to buy a Link D8. But I am far from dissapointed, I am just being patient.

You are entitled to your own opinion, but don't present it as a fact, unless you have proof to do so. You know better than me that your photo is no proof.

BTW, you could have just stated your cycling-related credentials. Your chess, maths, teaching, yoga and "healing" skills are off topic.



The frames and the failures have differences. However the point of failure is constant. Pleasee see my other post about the likelyhood of these events being independant. Statistically speaking this seem EXTREMELY strange.

I will spend my free time next week trying to find Tern's manufacturer...no guarantees.



You are not a shmuck! Rather a good hearted person that assumes the best.....I do not see a problem with that. I would expect such an attitude will bring joy to you and your family.



Thanks,

Yan



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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:27 pm


April 5, 2014 - 1:22pm
akpope

Country: UK



bikerrrguy wrote:

This is not a gut feeling. Given the probability of a bicycle frame breaking is amazingly low ( give it any estimate you want ). The probability of Tern's 6 known frame failures being independant ( different factory ) of SGM's 5+ listed on facebook is essestailly an impossible event. I am essentailly doing a statistical hypothesis test. My conclusion on this matter are true with HIGH probability.

I believe you can do your own hypothesis test on Excel.

Thanks,

Yan

I am sorry, but being a mere chartered engineer, without a professorship to my name, I cannot comment on the application of complex statistical theories.

However, if someone told me that

a) a batch of 100,000 bikes built on Mars had 5 failures, and

b) a batch of 100,000 bikes built on Earth had 5 failures

and that his proved a link then my reaction would be to check the timetable for space ships between the two planets. Bikerrrrrguys reaction would be that this proves that spaceships travel every hour, except for weekends when the timetable is reduced.

Turning off my sarcasm circuit, just because two manufacturers have the same failure rate does NOT prove that they are in any way linked. If two sets of bikes were made to the same design in the same factory then you would expect a similar failure rate. But stating that two similar failure rates proves a link the other way is not sound reasoning.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:27 pm


April 5, 2014 - 2:04pm
bikerrrguy

Country: USA


I agree with your arguement. You could use time variable instead of space ie. bikes produced in 1900, and 2000 had failures hence they must be from the same factory.

We must judge for ourselves if the hypothesis makes sense and applies.....the numbers don't lie. I believe the numbers with the hypothes applies to this situation, hence it is proof for me.



Thanks,

Yan

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:27 pm


April 5, 2014 - 4:15pm
akpope

Country: UK



bikerrrguy wrote:

I agree with your arguement. You could use time variable instead of space ie. bikes produced in 1900, and 2000 had failures hence they must be from the same factory.

We must judge for ourselves if the hypothesis makes sense and applies.....the numbers don't lie. I believe the numbers with the hypothes applies to this situation, hence it is proof for me.

Thanks,

Yan




perhaps my polite upbringing was at fault, or I was trying to be too subtle, but my argument was intended to show the utter absurdity of your analysis.

Perhaps I should be plainer in case anybody thinks that I agree with you (something that I would fnd mortifying). I do not agree with you. I believe that your argument is totally wrong.

I mentioned your argument to a music student, who has little training in maths, and she looked at me as though I was stupid for even repeating it.

The only valid discussion that can take place about this problem has to be based on an engineering examination of the actual failed bikes. Even from the limited photos it is clear that the tern bikes have had a failure in the weld, whilst the other bikes show welds that have not fused to the parent metal. Yes it is in the same location, but then that is the most highly stressed part of the bike so that is not surprising.

No manufacturing process if foolproof, and some failures will always happen, unless the item is massively overdesigned. What matters here is how Tern are investigating, what they do to help/reassure existing owners when they finish that investigation, and what they do to improve the design.

Raising specious psueudo science arguments and conspiracy theories does not help matters.

But Tern could help themselves by coming out of the shadows and tell us what they have found so far.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:28 pm


April 5, 2014 - 4:41pm
orbit
Country: UK



I think Tern do have to make some comment now. However Tern bikes are not the only folding bike with this design to break in this highly stressed area. It is that the design of this type of folding bike with the hinge in the middle is susceptible to this type of failure? After all that area is highly stressed and has no other support to fall back on(unlike a diamond frame}, so that area when it breaks the bike falls in half with the consciences that go with it. In some respects this has put me off this type of folding bike not just Tern. How other folders perform with an aluminum frame that do not have the hinge in the middle I do not know as I have not heard of any of those breaking although they may have the same problem as to not having the full support of a diamond frame and once a weld breaks the rider is down.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:28 pm


April 5, 2014 - 5:37pm
edwinic




Country: Philippines


Mr Yan, your gut feeling is that tern uses sgm as manufacturer and you supported with 5 pictures you took from the web. Thats all you have and nothing more.
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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:29 pm


April 5, 2014 - 5:42pm
edwinic




Country: Philippines


bikerrrguy wrote:

I agree with your arguement. You could use time variable instead of space ie. bikes produced in 1900, and 2000 had failures hence they must be from the same factory.



Thanks,

Yan

Fuck me, that is genius!

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:29 pm


April 5, 2014 - 6:30pm
akpope

Country: UK


edwinic wrote:

bikerrrguy wrote:

I agree with your arguement. You could use time variable instead of space ie. bikes produced in 1900, and 2000 had failures hence they must be from the same factory.



Thanks,

Yan
Fuck me, that is genius!



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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:30 pm


April 5, 2014 - 11:36pm
Keith C. Johns





Country: USA


bikerrrguy wrote:

Keith,

I learned of these problems about two months ago. My wife told me not to get involved, let it play. We both understood Tern was in serious trouble at the time.

Your wife has better sense than you. You should listen to her.

bikerrrguy wrote:

... After this I understaood Tern was dead. My wife reiterated do not get involved. Then Thor started posting some nonsense on this forum, so I called him and told him to stop. I shared all information with him. At the end of the conversation I believe he knew Tern was finished.

Tern is finsihed anyway, why would I risk myself to enter this thread? Once the forum went private I felt it is my job to get the truth out....




Mark Twain once commented, "The report of my death was an exaggeration." That this thread's speculations based on a small number of failed welds on Tern bikes will "finish" Tern is at best wishful thinking on your part. It is hyperbole: highly exaggerated well beyond any known facts--a wild leap of the imagination. And unsubstantiated.

Your logic is like 2 + 2 = Four Million! Even a worst case scenario wouldn't spell the end of Tern. Worst case: they find a design or manufacturing defect and recall thousands of bikes and repair the problem, and then resume improved production after taking this hit--a smarter company for this experience: hardly the end game you predict! More likely, they will narrow down the cause to a few batches where the welds were not done to specifications, and do a limited recall, and shortly thereafter increase sales thanks to this demonstration of Tern's dedication to dilligent aftermarket service. Again, NOT the end of Tern.

As much as you would like Tern to fail because it would leave more market share to your company, your judgment is clouded by your own obvious avarice. You plainly have a conflict of interest here, and rather than saving people from calamity, you are just trying to scare people away from buying Terns over to buying your own bikes. This fact makes me question all of your facts, and even makes me wonder whether you yourself realize that you are just serving your own interests here with your recent crusade. Take yourself out of this picture: if you didn't have a profit to make by warning people not to buy Tern bikes, would you be so eager to demolish Tern? And if Tern goes down, we will all be poorer as a result, you included. You need to see that this is not a zero sum game. It is possible to have a win-win conclusion.

Listen to your wife for once.

If I ever consider buying a Downtube bike, it will only be a result of your desisting from this attack mode you are in, and focusing on making your own bikes the best in the world instead of denigrating your competition's bikes. Just some business advice for you there, Yan.

As I have said ealier, my speculation is that Tern has miscalculated the balance between durability vs. light weight and after this will reconsider their decision to go with only aluminum frames with single downtubes. But this needs to be confirmed by their analysis, and we still need to be patient with them on this score. But if my speculation is right, they can radically beef up that weld or they can go back to Cromoly Steel frames, even with the same outer shapes they now have, and that will eliminate their fracturing issue. That is my advice, and I sincerely hope they are listening. (And I am not trying to sell my own brand.)

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:31 pm


April 6, 2014 - 6:03am
komiD7

Joined: 2014-04-05
Country: Austria



Hello everybody,

this thread started in december and we still have to wait for an answer from tern. All they have done so far is, they made this forum private. This may signal that we still have to be "patient" for a longer period of time.

From my point of view we don't have to be patient after almost 4 months. We need to know now if it is save to ride our bikes. If tern cannot exclude that they have a structural problem, then I think they should be so fair and advice us not to use our bikes until they have finished their investigations, because of the serious injuries that could result. And they sould tell us when they expect to finish their investigations.

If tern thinks it is save to use our bikes, then they should explain this by presenting facts. For example: We have sold xxx untis and have xxx known failures of the same kind - this is within the tolerance for bike frames and does not show an significant rate of failure. In this point I agree with bikerrrguy: numbers don't lie.

If we have to fear that tern wants to shut down this forum, then we have to move this discussion to a public bike forum now. After all I think it is not the best idea to keep this thread on the site of the producer, which has already limited access to this forum, which does not communicate with us and which is only watching us while we make speculations.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:32 pm


April 6, 2014 - 7:41am
orbit


Country: UK



Keith, your idea about steel frames I feel is a valid one. This is why I asked about Dahon. They make bikes out of both materials and it would be interesting to see if breakages in this area of the bike happen with the steel frames and if it does how does the numbers compare with the aluminum ones. I'm sure if Tern had made some bikes out of steel they would be in a better position in respect of not putting all their eggs in one basket. It would of infact given customers a choice if they deciced that they did not like the real or perceived problems with aluminium on this type of bike frame design.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:32 pm


April 6, 2014 - 4:00pm
vavavoom

Country: Greece


"bikerrrguy wrote:
The frames and the failures have differences. However the point of failure is constant. Pleasee see my other post about the likelyhood of these events being independant. Statistically speaking this seem EXTREMELY strange.

I am not going to say that you are overestimating numbers, since you're the math professor, but I will say that you are grossly overestimating your ability to give an explanation. Additionaly, you are appealing to probability here, which is a well known fallacy. I am not in the position to say whether you are biased towards an explanation or whether you have a malicious secondary gain out of this (as Keith said), but I will say that your train of thought - at least the one that you present here- is full of holes.

You do realize that what you are saying would have a great impact on others if it is true, don't you? So, why don't you say it AFTER you have the backbone to support it?

I mean, you just told 5 people that they threw a bunch of hard-earned money in the trash can (without knowing it) ....

You also told the rest that we can't expect for support, since the company is.... dead.

Please be careful.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:33 pm


April 6, 2014 - 4:37pm
ondrejp_sk



Joined: 2014-02-12
Country: Slovakia



Would the owners of the broken bicycles mind sharing the serial numbers of the frames ? Maybe just the first part ?

I am an owner of Link D8 bought in 12/2012 with serial AI1114... and tag TUJ91... and Taiwan made Link C7 AI1132... TNH30... bought in 5/2012 and am seriously worried by this issue. I honestly fear to use the bicycle. I am sure there are many more owners out there with similar mixed feelings.

I think Tern should hurry up with the investigation and publish the outcomes soon. This uncertainity is terrible.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:35 pm


April 6, 2014 - 6:13pm
Steveroot


Country: USA



ondrejp_sk wrote:

I honestly fear to use the bicycle.

I think (unless there is "official" information to the contrary) if you *inspect* the bottom of the frame joint on a regular basis you should have adequate "early warning" of an impending problem. As far as I can remember, none of the owners who have reported frame failures so far stated that they had been doing this. Why would they? But under the present circumstances, I think it might provide some security.

Here is my reasoning: most of the images of fractured surfaces show a darker color at the bottom of the weld, around 15-20% of the circumference. This is consistent with corrosion, which must have taken some time to occur. After this initial slow propagation, these fractures appear to have progressed rapidly, based on the accounts of the riders. My hypothesis is that these fractures would have been detected early, but *only* if they had been looked for. Again, this is not something a bike owner would normally be on the look-out for, and I'm not suggesting that the riders whose bikes broke were in any way negligent.

This hypothesis will be confirmed if someone reports finding evidence of a crack before the joint breaks, but this will happen only if the owners look *carefully* on a frequent basis. I would suggest once a week at least, or maybe every 25 miles or so. This is what I am currently doing since I'm as much in the dark as anyone else here. Another observation that makes me think this problem is not widespread is that so far no one has reported a crack that has not progressed to a complete fracture. Given the wide publicity given here and probably elsewhere, I think if the prevalence were high there would have been an early finding. Of course, in the absence of confirming evidence, this hypothesis is not supported. If no one looks for the early crack, none will be reported. So riders must use their best judgement.

However, I think the protocol I've suggested here may be a reasonable approach to continuing to use the bike with confidence.

I'd really be grateful for some sort of statement from Tern, though.

Steve

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:36 pm


April 6, 2014 - 7:24pm
orbit

Country: UK


Steve that implies that riders will actually see the defect.. True it would be worth every Tern owner to keep checking that weld. In some ways I hope someone finds a crack before the frame breaks not only would I be glad they found it before they were hurt, but it would also indicate that it is possible to stop a frame breakage while riding with inspection. The problem here is no one as yet has reported a cracked frame before failure. Your advice of checking the frame every 25 miles is a good one, but the riders must be able to know how to detect a crack and how it would appear to the eye.

By the way I have looked on the internet and have found steel bike frames of this design breaking at the welded area, although article did say that the bike had signs of corrosion on the area which suggested some propagation before the failure which suggests frequent checking may prevent incidents.Whether or not this will be the case with aluminum frames we will have to see.

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:37 pm


April 6, 2014 - 8:51pm
Steveroot

Country: USA



orbit wrote:

Steve that implies that riders will actually see the defect..

Well, they would have to look right at it. It also might be detectable by tactile means, using the finger tips which are often able to feel very small irregularities. Remember this is speculation.

orbit wrote:

... the riders must be able to know how to detect a crack and how it would appear to the eye.

That is why I said "So riders must use their best judgement."... I feel pretty confident that a crack with a minimal level of corrosion present would be detectable by someone who knew what to look for.

In my work as an endodontist, I see a similar problem with teeth: they develop cracks which may often be detected by visual and tactile inspection. The materials are different, but cyclic fatigue is cyclic fatigue. Of course, the potential consequences are generally less severe for my patients, who usually lose at most a tooth. Wink

Steve

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:38 pm


April 6, 2014 - 9:16pm
Plne


Country: New Zealand


komiD7 wrote:

Hello everybody,

this thread started in december and we still have to wait for an answer from tern. All they have done so far is, they made this forum private. This may signal that we still have to be "patient" for a longer period of time.

From my point of view we don't have to be patient after almost 4 months. We need to know now if it is save to ride our bikes. If tern cannot exclude that they have a structural problem, then I think they should be so fair and advice us not to use our bikes until they have finished their investigations, because of the serious injuries that could result. And they sould tell us when they expect to finish their investigations.

If tern thinks it is save to use our bikes, then they should explain this by presenting facts. For example: We have sold xxx untis and have xxx known failures of the same kind - this is within the tolerance for bike frames and does not show an significant rate of failure. In this point I agree with bikerrrguy: numbers don't lie.

If we have to fear that tern wants to shut down this forum, then we have to move this discussion to a public bike forum now. After all I think it is not the best idea to keep this thread on the site of the producer, which has already limited access to this forum, which does not communicate with us and which is only watching us while we make speculations.

This more or less nails it.

Tern is entitled to confidentiality and adequate time to work through the issue of these frames. And we are entitled to a greater degree of transparency and communication concerning what looks to be a potentially fatal design flaw.

They don't have to be mutually exclusive. Get on it Tern!

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Re: Tern Link D8 frame shearing in two

Post by Admin on Mon Apr 07, 2014 7:39 pm


April 6, 2014 - 11:00pm
Keith C. Johns



Country: USA


orbit wrote:

Keith, your idea about steel frames I feel is a valid one. This is why I asked about Dahon. They make bikes out of both materials and it would be interesting to see if breakages in this area of the bike happen with the steel frames and if it does how does the numbers compare with the aluminum ones. I'm sure if Tern had made some bikes out of steel they would be in a better position in respect of not putting all their eggs in one basket. It would of infact given customers a choice if they deciced that they did not like the real or perceived problems with aluminium on this type of bike frame design.

...By the way I have looked on the internet and have found steel bike frames of this design breaking at the welded area, although article did say that the bike had signs of corrosion on the area which suggested some propagation before the failure which suggests frequent checking may prevent incidents.Whether or not this will be the case with aluminum frames we will have to see.

I asked this question earlier in this thread and Thor informed me that he got more steel bikes than aluminum bikes back for warranty replacements when he was dealing with Dahons. After more debate, I was convinced that it is not just the materials but even more the design and quality of manufacturing which affect the bike frame's strength and durability over time. If you have time to read back over this thread, the entire discussion is within it. My conclusion was that a badly designed or poorly welded steel bike, for instance one made from too thin a stock, will fail long before a well designed and executed aluminum bike would--one with extra thick welds and tubes and with an over-engineered design. The original diamond design frames from a hundred years ago, were excellent, and would probably hold up much better than the single down-tube designs which are favored today, in either material. Sometimes we search for better and end up with worse, or worse which just looks better. So much of technology is fashion and marketing, and manufacturers cater to that and ignore what was better before: "If it ain't broke, fix it anyway and really bugger it up." I am not indicting Tern when I say this, but the entire industry. But I fear Tern may have fallen into this trap, too.

I don't want to suggest that if Tern just starts making their current bikes out of steel that automatically all the fracture issues would disappear: it would have to be done ADEQUATELY. Steel is stronger and more resilient than aluminum, and Chromoly Steel is one of the best in terms of strength per pound, but if you then make the tube 20 mils thick instead of 60 mils, for instance, it may still fail due to insufficiently strong design. There is no magic material which can overcome poor design. And even with a good design, a poorly manufactured frame can be worse than a bad design, as I suspect is the smoking gun in this thread's case--a bad welding job on a critical juncture. How far this extends has to do with batch sizes at that facility, and Tern has not been forthcoming on such details as of yet.

I still have faith in Tern and believe Josh when he says that his independent labs are testing everything thoroughly. I know that this takes time. What is a reasonable time? Is four months long enough? Six? Twelve? It seems that the longer Tern takes to resolve this sore, the more it festers; it is in Tern's own best interest to resolve this quickly.

It is as of yet unclear whether Tern has left the several people--now at six I believe?--out hanging in the wind or honored their five year frame warranties. Perhaps we should pole them at this point and ask whether they have gotten anything more than encouraging emails from Tern, if that. Even pending engineering analysis of the causes, surely Tern can afford to replace six bikes, even if only for good PR here. Any suggestion that they do not honor their own warranty can be a disasterous blow to their reputation. So guys, 1-6, please tell us how long ago you contacted Tern and sent back your bikes and whether you have received anything resembling a replacement bike. I hope my faith in Tern will be confirmed by your good results. Let's see, though.


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Re: Tern Link D8 frame shearing in two

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