chaadster

I suspect you wouldn't have heard of him.

Australian Custom Bicycle Show - part three - BikeRadar USA

Racing Dan

Framing it like that you wrote the conclusion too. Now lets try an other perspective.

Imagine we had two cars. Both were the same weight, both provided 200,000 miles of riding pleasure, blindfolded drivers couldn't tell them apart, but one had only 3 out of 5 wheel bolts mounted and the other had 5/5, would 3/5 matter?

Well duh .. Yes! Because the safety margin is much smaller. It might not matter for 99.99% of the time, but that one day you hit the pothole ...

Same goes for the poorly manufactured carbon bike.

I dont know why it was cut up to begin with, but its safe to assume it was in fact broken.

SethAZ 

Look, I'm open to the possibility that what we saw in that video is just evidence of a really crappily made, unsafe bike that could have killed someone in an instant if the wrong pothole were hit at the wrong time. I mean, I sort of threw up in my mouth a little while watching the video too.

All I'm saying is that a product development cycle typically includes consideration being given to how something will actually be manufactured. I'm no product design engineer, so I'm just trying to look at this with a very small amount of information and a little common sense. I am assuming that a company like BMC will set some design and safety criteria in place for the product they want to produce. This will answer questions like what sort of loads it must endure, what sort of durability it must show over time, as well as everything else like geometry, flexibility, stability in various dimensions, etc. Knowing what they (or their contract manufacturer) is actually capable of building, they will produce a design that they believe satisfies these criteria. If they are only capable of sloppy manufacturing, this may require compensation such as thicker layups, more reinforcement in certain areas, or whatever it takes to achieve their design criteria despite the sloppy construction. Then, during QC, they will evaluate the product and certify it if they believe that the design criteria were satisfied.

All I'm saying is that we don't really know, just based on some of the flaws we see after cutting it open, or how ugly it is or all the wrinkles of excess resin that accumulated in various places, etc. whether the design criteria were actually met. All we know is that that year the manufacturer wasn't capable of as neat of work as some other manufacturers.

If you've ever looked at a lot of old Soviet military hardware you get a better understanding of what I mean here. I mean, up close an AK-47 or a Soviet tank or other equipment just looks like crap. There are machining marks all over the place, things aren't always flat, nicely ground or machined, etc. Judged from a western quality sensibility it all just looks like pure unusable junk. But they clearly shoot, move, and are as durable as they need to be, because the designers knew what manufacturing capabilities would be used to produce it, and they designed around this to achieve whatever criteria were actually important to them.

memebag

He might know more about it than I do. He might be selling something, too. I don't have any reason to trust or distrust him.

Regarding higher grades of quality: I think we all understand what you are saying, we just don't think the different grades matter if they have no effect on the use of the finished product. A polished turd is still a turd.

But I don't know if the stuff we see in that video is analogous to 3 out of 5 wheel bolts on a car.

RPK79

Correct, he is trying to sell 10,000 AU custom frames.

Racing Dan

Of course it is. Just listen to the video if you are in doubt. He even said he Had a number of other BMC frames in with defects related to sloppy manufacturing.

pvillemasher

He was also in another "Carbon will asplode" video someone posted on on BF maybe a year ago (?) where some guy went into his shop and he pointed out all the cracked/ding'd carbon frames he was repairing.

He may be 100% reputable, I have no idea. I'm not saying he is overstating or embellishing.
I'm sure some of you guys remember that video. I'll look for it now.

EDIT: Who says the BF search sucks?
Cycling maven interviews a carbon repair specialist

dabac

From a strictly functional point of view, there might not be much difference between ”good enough” and ”better”.
But the thing with poor quality control is that it’s difficult to predict HOW poor it can be.
If there are big variations in production, how would you know that the next item out also will be ”good enough”?.

draganm

very interesting thread. Now I'm wondering if I'll chop open mt CF frame after it cracks ?

What's interesting is there also a video of Pinarrelo Dogma cut open from the same guy. It's better, not perfect, but better than the BMC but at 4X the price (rough guesstimate). The BMC was pretty bad, granted in only 2 spots, but those 2 spots are enough for me to not want to ride it.

I also think it's important to remember these are ALL made in huge frame houses in Asia. The only way the Company who's painting and slapping their name on it can ever be sure of the quality is to cut open every 10th or 20th frame. Or, have someone at the the factory inspecting the whole process, if that's even possible or allowed.

AFAIK the last CF frame big-name frame made in Europe was the Colnago CF40? Watching that video, you can what you're getting even if it was the older lugged CF design.

Seattle Forrest

I don't know what technique they use, but they make somewhat of a big deal out of the fact that their internals don't look all ugly like we're discussing. They don't make bicycle frames.

SethAZ 

I'm watching the video now with sound on (I watched it earlier silently). Once earlier on he was talking about an area showing some wear on the outside and remarked that if it were allowed for in the design that would be fine, if it weren't allowed for that could cause some problems. What he didn't say was "this was not allowed for, and therefor it is not fine."

At 8:09 he points the camera up close at some ugly voids in the junction between the seat tube and I think the seat stays, and says "the only thing really saving it is that it's a fairly low stress area on the bike..." So in other words, he points out the voids and other sloppyness in that junction, and then points out that that also is a fairly low stress area of the bike. Do you think maybe the designers actually knew that too? Is it possible that they were dealing with an area that they or their contract manufacturer (I don't know who makes their bikes) knew would be hard to form perfectly, and so they designed a solution that would take that into account and nevertheless be safe? Who knows? Luescher addressed the quality of that joint, not really whether it was adequate to the job it had to do. If anything, he tacitly acknowledged that maybe it is adequate, given the low-stress area of the bike in question.

I also heard several times when he remarked "if they allowed for it that would be fine, the question is whether they allowed for it", without drawing any conclusion on the important question.

I am not questioning Luescher's qualifications, nor do I disagree that specific things like voids are quality issues. What I do question is whether one could reasonably determine, on the basis of this video, and without recourse to the design and the design criteria that were set, whether that frame would function properly within those criteria.

SethAZ 

It's just engineering. If they can put an upper and lower bound on variation, then they can design in a margin that ensures safety and adequacy even at the extremes of the variation. The manufacturing process itself must then be engineered to ensure that these upper and lower bounds are not exceeded, and that if they are, this is noticed during QC so that the part can be rejected, the source of the problem identified, the process corrected, etc.

SethAZ 

I'll have to locate the original video, but Luescher had a video once where he showed a cross-sectioned carbon rim from one of the major expensive brands, in contrast to a cheap Chinese one. He showed various voids, inconsistent thicknesses, interior surface quality issues, etc. and then revealed which one was which. The expensive brand was the one that didn't look as nice.

I'm no design engineer or manufacturing engineer, but just based on videos I've watched of the processes they use to build these things it would seem likely to me that the simple circular bags they use for carbon rims would be far easier to make a pretty interior surface than the irregularly shaped bags they have to use on carbon frames, if only given the variations in interior dimension, corners, complicated cross sections, etc.

Bah Humbug

Framing it like that you wrote the conclusion too. We know that driving around with only three of five wheel lugs installed is dangerous. Do we know that a sloppy inside to a frame is dangerous? Do we know it makes the safety margin smaller? This thread is full of dire analogies and impressive credentials, but no "a sloppy inside makes the frame unsafe to ride". Note I said "unsafe" not "has less of a safety margin than otherwise, meaning it would only take an abusive 400lb rider to destroy it instead of an abusive 500lb rider".

Without resorting to analogy or declaration, does anyone know that that frame was unsafe to ride? I'm not asking for speculation that it might have been more likely than a different bike to fail under arbitrary abuse; was it dangerous to ride? BMC sold a lot of bikes and I haven't heard horror stories about them failing any more than any other brand, so I'm inclined to believe they're fine.

Doctor Morbius

No argument there!

Seattle Forrest

I don't think anybody knows for sure that it's unsafe to ride, or for sure that it's safe to ride. Like you, I think the fact that there don't seem to be thousands upon thousands of broken BMC frames is pretty good evidence that it's probably safe.

Steve B.

I got the impression there was a crack at the front of the seat tube, just above the top tube, which was marked in yellow. It's mentioned in the video and I took the meaning that the crack was why the frame was returned and inspected.

Bah Humbug

A lot of people are making declarative statements that it is unsafe, however. Comparisons to missing 40% of your lug nuts is exactly that. Or "susceptible to failure". Or compared to racing boats with dramatic talk of life and death. They certainly seem to think they know it's unsafe to ride, but I haven't seen a convincing statement of evidence.

memebag

Yeah, I listened to the video before I posted here. I don't know if he's truthful. I don't know of those are defects. I don't know of they are defects if they matter. Listening doesn't change any of that.

memebag

He said he found a void, I think via ultrasound, not sure. That's what he marked in yellow. The frame is 6 years old if the video was made this year. It might have a bunch of trouble free miles on it. Who knows?

kbarch

Frankly, it's not safety that concerns me - I'm not "concerned" at all. What I do care about, in a way, is how much the maker cares. I'm not saying the maker in this case ought to care more, just that I'm not interested in makers who care so little. Is a sloppy frame some percentage more likely to fail?
Who knows, forget that - it's definitely disappointing . That doesn't mean I won't buy their products, just that, when it comes to how they are made, I can be as indifferent as they are.
But I would rather they cared more and I would rather have something I could care about as well. Ugly things can do a fine job, but I like to say that beautiful, well-made things reward scrutiny. I like that kind of return on my investments.

danimal92sport

So much armchair Engineering in this thread! A good engineer designs something to be manufactured and then perform its intended use per the customer specifications and cost targets. No way was this frame designed without any understanding of supplier capability. As a matter of fact, they likely spent a year or more inspecting and testing supplier samples and early production runs to ensure that they got what they designed for and for what the expected cost should be. That's literally product development - which happens to be my profession (automotive, not cycling).

And being disappointed in the quality of a frame that is cut up to see what no one else sees or cares about at this price point is silly. Fact is, buyers tell manufacturers with their money what is important. If this stuff was important, y'all would pay for it, but few do.

I own a 2012 BMC and ain't surprised that this is what I payed for. I didn't buy an Impec or a Waterford and I knew that when buying. Apparently no one else did.

Dan

draganm

so far the Trek and the Canondale seem to be cleanest, best made frames. Hmmmmm?

that thin spot on the BMC, like really thin maybe 2mm or less, right at the joint between the BB shell and chainstay, what a death-trap

rpenmanparker 

Making spec is the definition of quality. Quality is the delivery to the customer of what he expects. It would be foolish to expect something not defined in the specification. Now, how many customers know what the specs are for a carbon frame? I don't know, but that is what they should know and what they should expect. A product that delivers what you expect is, by definition, high quality. (Sorry, but that is just the way it is.) If you know what a product's properties are, they meet specification, and the product is priced consistently with what it delivers, well, you can't ask any more than that. Even the BMC under consideration here should necessarily be considered high quality if the advertising properly described exactly what the test lab observed. You may not want it, but it would still be high quality.

cyclozone

Don't forget that the manufacturing of carbon fibre frames has generally improved quite a bit since 2011, especially regarding QC. The author of the video makes that point in some other vids. I do wonder if BMC has changed their manufacturing partner since 2011.