photo of broken fork

[Ken Robb]

Our favorite LBS is repalcing this EC90 SLX at no charge but I do think the customer is requesting a model with metal dropouts.

[cycleman_21]

scarey :bike:

[ergott]

Just speculation. Looks like the clamp wasn't sitting all the way in the dropout. It looks broken too low to have been in all the way. Could this be?

[gasman]

scarey :bike:


very scarey

[ergott]

Another thought. Do fork clamps have more leverage than a skewer? Is it possible that higher clamping forces put stress cracks in the dropout causing premature failure?
?
?
?
?

[nm87710]

How old is this SUB3 and how many miles??
SUB3's for the last 3+ years came w/aluminum dropouts.

[Ken Robb]

remember that this was the second fork -same model-to break within 5 minutes of each other. These riders are very experienced and have loaded these and other bikes in the same rack many times with no previous problems.

I wasn't there but anything is possible if not likely. Remember it was a very windy day so there were more sideloads than normal.

I'd be interested in an engineer's opinion of the wisdom of using carbon for a part like this where heavy clamping forces are required for the part to function. We worry about scratching and weakening handlebars, seat posts, etc. so what about the serrated teeth on a quick release digging into a carbon dropout. I suppose that's not a good comparison as the bars, etc. are hollow and made of impregnated CF fabric and the dropouts are solid compressed carbon. What do I know? I'm a real estate broker. :rolleyes:

[Ken Robb]

the whole bike is a few months old--not more than 2000 miles I would guess. It is an EC90 SLX in a Merlin Cielo.

[nm87710]

It is an EC90 SLX

That explains it. Didn't think it was a SUB3.
Easton's skill is manufacturing and sales - not engineering design.

[Big Dan]

Wonder what the coach would say............. :eek:

[e-RICHIE]

Wonder what the coach would say............. :eek:



mon dieu.*



*french for "my dieu".

[zap]

I have to admit that when I first saw this type of dropout, as much as I like carbon composites, I thought these "forged" carbon composite dropouts where a little premature for the consumer market.

I would be surprised if wind would cause this though. Going around corners fast in a car would probably put more load on the dropouts than wind.

I'm not an engineer. I just sell stuff.

[d_douglas]

Makes me want a steel fork.

[Jeff N.]

P.O.S..Jeff N.

[ergott]

If you look carefully, there is a faint outline of a circle which looks like where the fork was clamped. The center of that circle is not in line with the theoretical center of where the axle should sit in the dropout. I would like to see more detailed pictures. If you have a pic of the same fork that is undamaged side by side, that would be even better.

[bcm119]

I'm with ergott here. I think the most likely cause is user error. If the thing was tightly clamped all the way onto the rack, a side force would have broken it further up, above the flats of the dropout. Also, how can one side break and not the other? A tightly clamped fork creates a rigid triangle with the rack skewer, so one side would have to have slipped out first.

But it makes for good anti-carbon propoganda.

[Serotta PETE]

THis is very very scary and one of the reasons I stick with SEROTTA branded forks. This type of problem should not have happened - FOR ANY REASON!!!

I am sure some will argue with me - - - and that is fine...It is just my personal opinion. We can discuss over a red wine with FLYDHEST> He has recommended some OUTSTANDING wines. THe people I work with got me some of his suggestions when I retired in SEPT> Only sad note is that he was not here to share them with me.

PETE



remember that this was the second fork -same model-to break within 5 minutes of each other. These riders are very experienced and have loaded these and other bikes in the same rack many times with no previous problems.

I wasn't there but anything is possible if not likely. Remember it was a very windy day so there were more sideloads than normal.

I'd be interested in an engineer's opinion of the wisdom of using carbon for a part like this where heavy clamping forces are required for the part to function. We worry about scratching and weakening handlebars, seat posts, etc. so what about the serrated teeth on a quick release digging into a carbon dropout. I suppose that's not a good comparison as the bars, etc. are hollow and made of impregnated CF fabric and the dropouts are solid compressed carbon. What do I know? I'm a real estate broker. :rolleyes:

[shaq-d]

mon dieu.*



*french for "my dieu".

sacre bleu!

which means soccer blah.

sd

[Tom Kellogg]

As frightening as that photos is, we have seen lots of them, but never one on a carbon drop. We get roof rack failures just like the one in the pic about five time a year. They are usually of aluminum dropouts though since most forks have aluminum drops. I don't really like the idea of carbon drops either, but in this case, don't blame the material, an aluminum drop would have done the same thing ... Bummer.

[nicrump]

This happened in the rack? That’s a perfect triangle. If one broke then the other would have to be damaged as well or… consider the possibility the damage began when the bike was lifted out of the rack, got slightly cocked and the drop out closest to the guy was still in the rack.

Were both dropouts damaged?

[columbusslx]

nicrump, I agree with your take...pilot error...no JRA here.

[chrisroph]

I hate pictures like that. My teeth ache just looking. TK, what is the typical cause. Is it usually a roofing job?

Re wine, try a 2002 domaine serene evenstad reserve if you can find it.

[Johnnyg]

A good case for Ti dropouts!

[Tom Kellogg]

TK, what is the typical cause. Is it usually a roofing job?

From our experience, there are a number of ways that this sort of thing happens.

Not fully inserting the dropouts onto the carrier axle before tightening the QR.
Not fully tightening the QR.
Using a QR that has a poorly designed cam. Common among carrier QRs.
Not securing the rear wheel properly.
Cornering in a way that resembles the way that Pro Team directors drive their support cars during races.
And finally ... USING A ROOF RACK ... to begin with. DON'T DO IT!

Please keep your bikes inside your cars. I don't see other stuff worth $6,000.00 on top of cars very often.

[David Kirk]

It's a funny thing to me. This design works more often than not I guess as not every carbon dropout fork out there fails but...........there is something deep inside my common sense that says taking some cloth, saturating it in some glue, clamping the crap out of it, and then trusting your life to it just doesn't make sense. A broken front drop can and will kill you....no joke.

I imagine that at sometime in the future they might work out the compression failures common with carbon stuff but until then let common sense be your guide and remember that most manufacturers don't nessessarily have your best interest in mind.

Dave

[Roy E. Munson]

THis is very very scary and one of the reasons I stick with SEROTTA branded forks

What difference does that make?

[bluesea]

I imagine that at sometime in the future they might work out the compression failures common with carbon stuff but until then let common sense be your guide and remember that most manufacturers don't nessessarily have your best interest in mind.

Dave

Dave,
This particular incident wasn't a compression failure. Are you refering to another type of failure?

[vaxn8r]

Let's see both dropouts before making any assumptions.

[Chief]

Ken, Please check your PM.

[David Kirk]

Dave,
This particular incident wasn't a compression failure. Are you refering to another type of failure?

I was talking about the compression of the QR skewer. Once the epoxy crushes or breaks down all you have is black treads.

Dave

[cpg]

There's two facts as I see it. Fact #1 Without extensive testing, it's difficult to say with any certainty what caused the failure. Everything has been speculation so far.
Fact #2 It failed in a way (catastrophically) that many other materials won't. That's a fact. We can quibble about whether it was operator error, manufacturing blunder, cross winds or poor design but all of that seems to miss the point. It failed and miserably. There's never a good time for this kind of thing and one time is too many.

Curt

[vaxn8r]

There's two facts as I see it. Fact #1 Without extensive testing, it's difficult to say with any certainty what caused the failure. Everything has been speculation so far.
Fact #2 It failed in a way (catastrophically) that many other materials won't. That's a fact. We can quibble about whether it was operator error, manufacturing blunder, cross winds or poor design but all of that seems to miss the point. It failed and miserably. There's never a good time for this kind of thing and one time is too many.

Curt
Your second point is a huge assumption. Anything can fail if abused or used improperly. What if the guy had a rear rack and he failed to secure the bike and it fell off the car at 60mph and trashed the frame? Would that be considered a catastrophic materials failure? Since the photographer only showed the one drop out, I suspect the other side was OK, which meant he/she improperly clamped it in the fork mount of the rack. To me that is not a failure of the equipment but of the operator or of the rack's QR design or both.

OTOH, if both dropouts look like that you have a point. But then why not post pics of both sides? IMO The guy probably screwed up.

[Big Dan]

It's the anti carbon propaganda.................. :eek:

[cpg]

I agree. Everything can fail. How it fails is where things can get messy. Failure modes are important. It's called a catastrophic failure because it broke off. Other materials would have folded but stayed in one piece. When carbon fails it's called a catastophic failure. Carbon bends to a point and then when it's tensile strength is exceeded it breaks into pieces. It doesn't deform like Aluminum, Ti or Steel. This isn't implying anything. It's just a term used in measuring these sort of things. Again, I'm not ripping on carbon and I don't see where I've made any assumptions.

Curt

[asgelle]

Fact #2 It failed in a way (catastrophically) that many other materials won't.
Maybe so, but my girlfriend's aluminum dropout failed in the same way. While there may be many other materials out there, take away carbon fiber and aluminum and there aren't a lot of dropouts left.

[cpg]

Rumor has it steel works. Of course, what would I know.

Curt

[asgelle]

Rumor has it steel works. Of course, what would I know.

Curt
E pluribus unum

[ergott]

There's two facts as I see it. Fact #1 Without extensive testing, it's difficult to say with any certainty what caused the failure. Everything has been speculation so far.
Fact #2 It failed in a way (catastrophically) that many other materials won't. That's a fact. We can quibble about whether it was operator error, manufacturing blunder, cross winds or poor design but all of that seems to miss the point. It failed and miserably. There's never a good time for this kind of thing and one time is too many.

Curt


Before we get all happy about how much carbon can "catastrophically" fail, it's not always the case. I've seen a couple of carbon rims damaged from heavy impacts. I cracked a big nam bar/stem combo in a sprint once. There was no installation error and the company gave a replacement part under full warranty. Anyway, the bar/stem failed, but did not cause me to go down. Not even close. I had no problem coming to a stop. (PM me if you want pics of the bar, it's pretty cool). Carbon can fail and so can ANY material if it's poorly engineered. Any part is only as good and the engoneer and fabricator that made it.

http://websites4ever.com/ergott//damagecloseup.jpg

This rim was hit by a 2X4 at 30+mph when the rider wasn't looking. At that speed many rims would have had significant damage. This rim was still ridable. In fact the wheel wasn't even out of true. The only reason the damage was noticed was that the uneven brake track was felt when the brakes were used (that and the fact that the impact scared the crap out of the guy!). The rider was in no danger of crashing (other than from hitting a 2X4!!!!). Carbon doesn't alway fail like you would like to believe. I did see one set of carbon wheels broken in half (catastrophic failure), but that was after a crash when at least one rider rode OVER the wheels. You can kiss any wheel goodbye after that.

[jeffg]

Food for thought.

http://www.insidetri.com/train/bike/articles/1843.0.html

Most modern rigs come with integrated HS (without replaceable bearing races), carbon fork dropouts, or both! :crap:

I'l stick with my Chris King HS and F2 or Alpha Q for now, thank you