northernlights

Now you're saying Dahon is no good? Just curious, why do you say that? Just because the owners are related? I have a owned a couple of Dahons, they were built like a tank. Like you said we are living in the age of the internet so if Dahon were making bad bikes you would most certainly hear about it from people. I don't think they got to be one of the oldest, probably largest most well-known folding bike company in the world by building bad products. They are not the same company.

berlinonaut

That's not what I am saying. What I meant was that a Tern is not worse than a Dahon for most people and maybe better for some for one reason or another. Or the other way round. Depends on your needs. Personally I do not like Dahon bikes for many reasons, but that's a personal opinion and preference. If you lived in Germany I'd recommend to stay away from Dahon due to a total lack of spare parts over here - people are using Tern parts as Dahon parts are hard to find and sometimes impossible to get hold of. According to Thor a different story in the US. I've heard a bunch of stories about defective Dahons becoming a total loss due to worn hinges and broken frames, beyond repair and with no spare parts available. I do not like the hinge clamps that Dahon uses as they seem to need more maintenance as i.e. thos of the Brompton. The model lineup of Dahon over the years is a totally confusing nightmare as is the availability of different models in different markets - totally intransparent and continuously changing as are the technical data. etc. etc.

But let's honor the thread topic please - most of our discussion would have been unneccessary if you had read the thread you were posting to before posting. So let's at least stick to the topic.

xedapgap

I have a Dahon Mariners and thoroughly enjoy riding it every day

Bonzo Banana

I think a factor is the weight limits of bikes and the fact this information isn't clearly presented to the customer. Lower weight bikes are more pleasant to ride but often lead to lower weight limits and a higher risk of failure. Generally Dahon, Tern and Decathlon Btwin bikes have low weight limits and also suffer from the most recalls for frame failures.

In the UK we have a large chain of shops called Halfords that sell their own brands of bikes, they state a maximum rider weight of 120kg with 20kg additional weight loading away from the seat tube for adult bikes. They also state an absolute maximum 160kg loading that you must not exceed and rarely if any suffer from frame recalls despite having a large percentage of sales in the uk for bikes. Decathlon state 100kg maximum load weight but also include the weight of the bike meaning a maximum rider weight including clothes, luggage etc of 80-90kg depending on bike type. You'd not know there was such a difference going into either store as this information is concealed in the manuals and nowhere else.

If it was the law that every bike had to have a clear maximum load label on its frame we may find many of these recalls would disappear but also sales of low strength bikes would significantly drop.

Dahon is a confusing brand because I think their bikes have been all over the place regarding strength. Some of their non peformance early steel bikes seem strong, their more recent performance bikes are fairly weak, the new Curl looks strong but I seem to remember they did an earlier chromoly steel peformance bike that was actually quite weak with thin tubes. I don't think Tern has ever made a strong bike, they are clearly focused on the performance side of bikes.

Clearly many of these comments are about the durability of hinges of folding bikes. I must admit I'm unsure reading the comments if the failure of these is purely through the wear or fatigue of purely opening and closing such hinges or the fatigue of the hinges flexing while riding or a combination of the two. I'm sure though the weight of the rider in many cases is a factor. In the old days you used to get over-engineering allowing for the worst case scenario and making something strong enough to cope with that. Many of the early steel folding bikes of 50 years ago are still going strong and likely to outlast their modern aluminium counterparts despite the age difference.

tds101 

Thanks!

downtube

One of my biggest concerns stems from the older women that was touring with her husband, both were riding Tern Verge bikes. Unfortunately, her frame snapped. I recall that she checked the serial number and it was not recalled and she contacted Tern, but later she checked again and it was recalled. She was very confused. I think it would be prudent for anyone with a broken frame to take a picture of the Tern's recall page. I would not be surprised if they added broken frames to the list after the fact.

Thanks,
Yan

sweeks

They probably didn't need a recall until a frame actually broke, don't you think?
Steve

downtube

Are you serious?

Thanks,
Yan

sweeks

Well, yeah, I was. I doubt they just decided to have a recall for the heck of it. And expanding an existing recall was probably done for a reason.
Of course, I'm not "of the industry", so what do I know?
Steve

downtube

Steve,

The point of a recall is to address products that are "at risk". Adding to the "at risk" pool after a known failure compromises the whole point of a recall.

Let me clarify....It is improper to issue a recall for 100 products ( out of a thousand at risk ) and add to the list as each of the at risk pool begins to fail.

I am not saying Tern did this, but I am suspicious after one customer claimed an ambiguity of their bike on Tern's site. Additionally the CPSC doesn't have a complete list of serial numbers, which is awkward.

Thanks,
Yan

sweeks

I get this. The question has to do with how the products are known to be at risk. I don't have any special knowledge of this, but I'm guessing that no one knew the products were at risk until there were failures.

This is the part I don't understand. I have a Tern bike. Shortly after I bought it, I was aware of the recall but my frame was not involved. Subsequently the recall was extended and my frame *was* involved. My understanding was that there were frame failures *outside* of the group of frames originally recalled, and so the recall was extended to include frames that had something in common with the more recent failures. I don't know how this is done (ranges of serial numbers, manufacturing dates, shifts, etc.), but I assume there is an effort to include all the frames that are likely to have a problem without recalling every frame ever made.

If 1,000 were at risk, why would only 100 be recalled? The products would be considered "at risk" because they share some significant feature with the one(s) that failed, as I indicated above.

I probably need to go back to school to more fully understand the nuances of manufacturing.
Steve

downtube

I apologize for my lack of clarity.

I am creating a hypothetical situation. Assuming 1,000 products are at risk however the manufacturer for whatever reason chooses not to recall all the affected products. Let's assume they recall 100 units. After a failure they can add the failure to the list of recalled products .....in short putting the blame on the customer.

Overall I think it would be prudent for affected customers to take a picture of the website if their bike was not recalled....just in case anything funny is going on in the background.

I still don't understand how Tern is recalling certain bikes and not others. I do not believe they every explained the fault....am I incorrect? If so please enlighten me.

Thanks,
Yan

jur

Steve, read back over this thread, between posts 30-40 where I explained weld design philosophy. The reason I think the recall started small was simply to limit their losses. I strongly suspect Tern knew about their dodgy weld design right from the moment they started getting broken frames back, but what are you going to do as a company to survive? You can't recall your ENTIRE sold stock and your warehouse stock, that will surely send any company broke. So they probably recalled as few bikes as they could, blamed it on dodgy manufacturing instead of faulty design. That way, they could issue a limited recall over a range of serial numbers. But as more and more frames broke, they were forced to expand the recall. In the meantime they introduced the reinforcement which you have on your bike.

downtube

I wanted to share a letter I received a while ago from Tern's attorney's. Please understand in 2011 I was living & teaching in the Bahamas. Additionally, I considered myself a full-time chess player, hence I was not as active in the cycling community. I had no idea who ITMS is, nor did I know anything about the nonsense with Tern until I read about it on bicycleretailer. I laughed at the claim that I orchestrated the entire thing.

Then they claim my postings on THEIR forum are defamatory.....but they own the forum. They control the information posted & can delete anything. Once Tern approves the posting, it can not be improper or illegal. My attorney laughed at the ridiculousness of this claim.

FYI defamation can only occur to an individual or company with a good character

Thanks,
Yan

sweeks

I didn't realize you were in bike manufacturing!
I'm not, so I don't know how design flaws are evaluated or recalls are instituted. But I tend to think the best of people, so I'll continue to think that, awful, awkward and embarrassing as this must have been for Tern, it was handled appropriately. I've also noticed that recalls of bikes and bike parts are not particularly rare, and I suspect they are more the result of human error than willful disregard for the well-being of others.
I'm also not interested in more gratuitous "Tern-bashing".
Cheers,
Steve

Technician

The more I read about this whole issue of frame failures the more convinced I am the fault lay in the original hinge design.
If you look at the latest latches both OCL and FBL 2.0 you can see how they clamp together more securely than earlier types minimising torsional stress on the frame through movement.
The FBL latch is particularly good I think as one hinge surface sits inside the other rather like a door when it's shut into it's frame.
I'm less inclined to believe it was a welding fault as the welding appears to be exactly the same on newer models, all that's changed is the frame latch.
I've see some of the paperwork that's given by some manufactures to stockist who sell folding bikes, and there's great emphasis on the need to get across to the customer the importance of making sure those hinge bolts are secure. To quote one cycle manufacturer "
Advise that an incorrectly adjusted Folding Joint may cause Frame damage or result in user injury " that's clear enough to me, actually Tern, Dahon and others all issue similar advice. In fact there's more emphasis on the latch being correctly adjusted than on making sure your wheels are bolted on securely or bars are tight !

jur

Improperly fastened/tightened hinge puts enormous strain on the hinge joint, not the welds. We saw a Dahon version of the stempost hinge break in the hinge when these were ridden while a bit loose. The Tern frames broke right through the welds. The hinge design is not to blame, but the amount of welding. Once they introduced an internal web that enabled the weld length to be increased, the increased welding strengthened the weld by a certain percentage, making weld failures less likely. If it were truly manufacturing to blame, i.e. bad welding, then strengthening the weld should not have been essential. But a weld should be over-designed such that even with bad welding, there should be ample strength to carry the load.

But it is certainly not the loose hinge causing weld failures, as the stress is elsewhere.

Technician

I haven't seen any Tern hinge welds up close and personal lately, but I'll certainly be having a closer look in the future the next time I visit a bike store. It's difficult to see looking at images online of the latest Tern folders but I have to say they don't appear to have any extra welding around the frame hinge area. There's nothing visible on the Vektron for example a heavier bike with even more stress to handle.
A new hinge design can be seen however, by new I mean updated from the original version with a greater interlocking surface.
Both OCL and FBL hinges look to have this same idea of a greater interlocking area set further forward.

tcs

Post #94!

tcs

If you've read the whole thread (& others), then I'm afraid you can't think the best of all the people involved. Either the company hasn't handled this well, or there's a conspiratorial smear campaign involving multiple customers.

bhkyte

Look widely at the evidence against Tern.
Please don't give them the benefit of the doubt, that would be a major injustice to this immoral company.

tcs

Sometimes you get the bear; sometimes the bear gets you. Andrew Ritchie describes dodging a bullet on a potential company killing frame recall @ 36:50 to 38:00 in this video:

Technician

That's where Josh Hon keeps going wrong...he lacks the upper class accent


The problem with adding extra bracing struts or any kind of internal or external abutments is they require welding in position. When you take into account the fact that alloy welds unlike steel can be significantly weaker than the metals they're fusing together thus you're compromised, more could well mean less so to speak.
I have to say the sight of a weld running along the bottom of an alloy bike holding something in place designed to strengthen the integrity of the frame does nothing for me. Instead of a Band-Aid why not just build a stronger frame in the first place. I think I'll stick with the improved latch as the key to it.
I'm sure every bike builder out there is not suddenly welding more material to their frames in panic they could be next, however I am seeing improved hinge and latching systems cropping up on many brands.

tcs

Not a rare thing by any means in bicycle frame design.

gusset.jpg

dahoneezz

See the failure? The frame metal tube is intact. What has failed is the weld (to oval hinge plate). The welding is cicumferential around the tube. As Jur has stated, the weld is weak when forces is across/normal to the weld. By adding a gusset plate connecting oval hinge plate to botton of front frame, you will be running weld in line with the frame. The forces will be inline to the new gusset weld. Stronger.

Improving hinge and latching, is not fixing the problem.