Carbon failure at Tour du Doubs sprint

[Peter P.]

Any evidence that's ever happened with a steel steerer?

Just sayin...

[Burnette]

Originally Posted by colker

Irony being: equipment is validated at these pro racing events. Teams have the best mechanics and manufacturer´s support. When things break the math in people´s minds is: equipment is no good.
The high wattage these racers put out tests parts to the limit. It should not break.

You're right about that. I would like to see what the cause was but I would bet we'll never know, or we will be told something untrue to save face.

I'm glad the rider came our OK, the video I linked above showed how he unclipped before going down, that was heads up riding.

[azrider]

Originally Posted by Burnette

Another take on the incident:

https://youtu.be/NQJUSZeJE8A

dang......crazy how well rider kept it upright considering it broke long before it appears to have broke. Agreed that the clipping out is super heads up riding......expect nothing less from pro

Thanks for sharing

[zmudshark]

Originally Posted by Burnette

Another take on the incident:

https://youtu.be/NQJUSZeJE8A

Originally Posted by azrider

dang......crazy how well rider kept it upright considering it broke long before it appears to have broke. Agreed that the clipping out is super heads up riding......expect nothing less from pro

Thanks for sharing

Thanks for posting, and az is right, pro skills.

[KJMUNC]

There's the "O-face" and then there's the "Oh $hit" face....this is the latter

[dddd]

I imagine that being able to conclude that enough testing has been done on this part of the bike can be a very tall order.

I've seen how when some of the steerer inserts have a flange along their top, it forces some extra couple of mm to be cut from the steerer's length.
And if there are no spacers atop the stem, then that couple of mm is added to whatever needed space is needed for the part of the top cap that settles into the steerer. At this point the stem is applying clamping and bending loads along only a portion of it's interior clamping length, and is clamping hard on the very end of the steerer, creating a slightly cone-shaped distortion within the inside bore of the clamp. This is scary.

So unless steer tubes are tested under these conditions, and using the exact type of steerer insert at a standard tightness in terms of expansion, then the results can be unpredictable.

It would be interesting to find out how far through the rider's stem clamp that the end of the steerer reached in this case.

I always like to see some of the actual steerer protruding above the stem, especially on bikes that are ridden by heavier/stronger riders than myself.
And where no spacers are used above the stem, I like to use a flush-bottom top cap instead of a stepped-bottom cap, so the steerer can come up further through the stem clamp.
And I don't like to see a steerer insert used that has a flange at it's top that further reduces the length of clamping purchase on the steerer.

Perhaps all stems should have a bit more clamping length than the ~40mm or so that we are typically seeing these days, but instead we are seeing stems with closed tops in some cases that would appear to allow no safe range of height adjustment.

[bigbill]

I'm a firm believer in 3mm spacer above the stem so the clamping surface is all steerer and not over the top.

[weisan]

.

[Hellgate]

I'm thinking the bike had been crash already. The ride then the sprint finished it off.

That said, a Bianchi broke off at at the steer tube last season. A Spring race IIRC

[dddd]

What mad bike handling skills, no?

It appears that he maintained some ability to steer the bike with the center of the handlebar against the front tire?

This reminded me of a recent WILD ride one racer lived to talk about that almost defied mortal abilities (and was similarly caused by a mechanical failure):

https://www.youtube.com/watch?v=wJaZ4t8Jfn0

[zmalwo]

unfortunately carbon products have no uniformity. while carbon fiber itself is always consistent in molecular structure, the resin/carbon mixture is not always so consistent. Voids, folds, resin dry/rich, all contribute to the randomness of it sometimes manufacturers pass off stuff as good even tho their scans show all the defects.... when you hit a jackpot of these defect concentration you will have a bad day....

[zmalwo]

8 out of 10 carbon failure related crashes stem from the forks, so I wonder why don't the manufactures layer up a few extra layers of carbon on all the weak points like fork blades, lower tapered area, and steerers. adding 200g to the most failure-prone area doesn't seem like a bad idea.

[Ronsonic]

Way, way back in the day, wasn't it fairly common to jam a sized dowel up the steerer tube. That was on 1" steel threaded steerers.

A birch dowel would not weigh much and would offer one hell of a lot of reassurance here.

[54ny77]

Eeeeeeyyyyyyouch.

That hurt. To watch too.

[BdaGhisallo]

Originally Posted by Jaybee

I agree. That is clearly celeste.

To the larger point, sucks for the rider, amazed how long he kept the inevitable from happening, almost certainly an installation error just like the Hincapie thing. (Wasn't Hincapie on an aluminum steerer though?)

The details I recall were that Trek were rushing out some forks to the Discovery team in time for P Rbx - carbon forks with aluminum steerer tubes. The essential problem was that, in the rush to get them finished and shipped, the steerers weren't properly heat treated.

And let's not forget that Hincapie had already crashed earlier in the race before he had the crash that we all remember which sent his bike and his handlebars off in different directions.