Carbon failure at Tour du Doubs sprint

[paredown]

Originally Posted by 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

Yes! And he unclips, so he lays it down instead of going endo, as the Aussie video notes.

Mad Skillz!

[tctyres]

Originally Posted by Peter P.

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

Just sayin...

I get that you're being cheeky, but steel doesn't get raced. I doubt he would have taken 5th in a pro race on a 184km course with steel. The aerodynamic drag on the fork is prohibitive.

As for history, there are plenty of broken 1" aluminum stems from the pro peloton. Even farther back, there were all sorts of failures with steel forks. The type of failure that comes to mind is the separation of the head tube at the fork crown. This caused a lot of racers to jam broom handles in the bottom of the steerer tube and cut them off. Every now and then a vintage bike shows up with a "cornuellet" (sp?) which is the broom handle in the steerer.

[benb]

Originally Posted by tctyres

I get that you're being cheeky, but steel doesn't get raced. I doubt he would have taken 5th in a pro race on a 184km course with steel. The aerodynamic drag on the fork is prohibitive.

As for history, there are plenty of broken 1" aluminum stems from the pro peloton. Even farther back, there were all sorts of failures with steel forks. The type of failure that comes to mind is the separation of the head tube at the fork crown. This caused a lot of racers to jam broom handles in the bottom of the steerer tube and cut them off. Every now and then a vintage bike shows up with a "cornuellet" (sp?) which is the broom handle in the steerer.

The aero drag on the fork wouldn't make that much difference. You're buying modern bike marketing way way too much. Remember all that aero marketing is trivial #s of watts compared to the riders positioning and behavior.

If the whole bike was steel and had a vintage steel weight maybe that would make a difference on a hilly/mountainous course.

Carbon fork with steel steerer I am having a hard time believing would have kept him from placing.

[dddd]

Originally Posted by tctyres

I get that you're being cheeky, but steel doesn't get raced. I doubt he would have taken 5th in a pro race on a 184km course with steel. The aerodynamic drag on the fork is prohibitive.

As for history, there are plenty of broken 1" aluminum stems from the pro peloton. Even farther back, there were all sorts of failures with steel forks. The type of failure that comes to mind is the separation of the head tube at the fork crown. This caused a lot of racers to jam broom handles in the bottom of the steerer tube and cut them off. Every now and then a vintage bike shows up with a "cornuellet" (sp?) which is the broom handle in the steerer.

Perhaps it was first the racers who put wood dowel in their steer tubes, but the major manufacturers eventually also did this on popular models, even though it could cause water to be trapped inside (these were quite closely-fitted).

Production steel frames gained weight over the years to meet more-stringent standards for strength as carbon frames and forks got ever lighter. I remember the day that someone brought me a (Tange Prestige-tubed) Soma frameset to be built up, and how shocked that I was by it's heft when it was handed to me. Custom builders are free to build precisely to the customer's weight, so can create a much lighter steel frameset.

It seems fortunate to me that 1" quill stems can still be made to modern standards (and at low cost) in both steel and aluminum!

[tctyres]

Originally Posted by benb

The aero drag on the fork wouldn't make that much difference. You're buying modern bike marketing way way too much. Remember all that aero marketing is trivial #s of watts compared to the riders positioning and behavior.

If the whole bike was steel and had a vintage steel weight maybe that would make a difference on a hilly/mountainous course.

Carbon fork with steel steerer I am having a hard time believing would have kept him from placing.

Sure, positioning matters more than the shape of the fork blades, but we're talking about a group of pro racers who leave the upper part of their handlebars untaped to save watts. The rounded profile of a steel fork would be the problem as it sheds vortices poorly. The weight is only secondary at the speeds they are maintaining.

As for a carbon fork with a steel steerer, you're probably right. I doubt that Bianchi would offer that to their teams, though.

[Mark McM]

Originally Posted by Peter P.

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

Just sayin...

I've witnessed it happen. In the New England District Championship road race one year I was at the feed zone, supporting a rider on my team. As the 1/2 race came by, a child ran out into the road (I think he was trying to give a water bottle hand up to his father). One rider had to slam on his brakes to avoid running into the child. As the rider braked, his steel fork steerer snapped (at the crown), dropping the rider to the ground. Fortunately, the feed zone was on an uphill, so the riders weren't going very fast, and the crashed rider escaped serious injury.

[Mark McM]

Originally Posted by 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.

It was also common to throw a pinch of salt over your shoulder for luck. Both were equally effective.

[Mark McM]

Originally Posted by dddd

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.

How does a flange on the top of the steerer insert force the steerer to be cut shorter? All the extra height would do is increase the spacer stack a couple of millimeters higher above the stem. I always cut carbon steerers with a generous amount of length above the stem (if nothing else this allows a little stem height adjustability), so a couple of millimeters of spacers isn't even noticeable.

[benb]

Originally Posted by tctyres

Sure, positioning matters more than the shape of the fork blades, but we're talking about a group of pro racers who leave the upper part of their handlebars untaped to save watts. The rounded profile of a steel fork would be the problem as it sheds vortices poorly. The weight is only secondary at the speeds they are maintaining.

As for a carbon fork with a steel steerer, you're probably right. I doubt that Bianchi would offer that to their teams, though.

How many watts does not taping the bar top save? 1W? The fork legs? A couple watts?

If the rider misses out on getting a good draft or gets in bad positions or sits up on the bar tops when they shouldn't that stuff is all way way more significant than these little things the bike companies tell us mean everything.

I don't know how you measure this stuff... Watt*Seconds or something? Sure a fork that has 1W more drag has that for the whole race.

But missing a draft for a minute or two here or there as the race goes on would add up to many thousands of these Watt*Seconds.

There's no reason if you're in the race not to take advantage of some of this stuff but it doesn't mean if a team didn't that it would be a make or break difference.

[Ronsonic]

Originally Posted by Mark McM

It was also common to throw a pinch of salt over your shoulder for luck. Both were equally effective.

Acknowledging it wouldn't have done much for a steel steerer, in this case it would've saved the guy some skin.

[zmalwo]

Originally Posted by tctyres

I get that you're being cheeky, but steel doesn't get raced. I doubt he would have taken 5th in a pro race on a 184km course with steel. The aerodynamic drag on the fork is prohibitive.

As for history, there are plenty of broken 1" aluminum stems from the pro peloton. Even farther back, there were all sorts of failures with steel forks. The type of failure that comes to mind is the separation of the head tube at the fork crown. This caused a lot of racers to jam broom handles in the bottom of the steerer tube and cut them off. Every now and then a vintage bike shows up with a "cornuellet" (sp?) which is the broom handle in the steerer.

It will if UCI didn't set the weight limit so low. 6.8kg is not adequate to safely construct a bicycle at all. When it comes to human life statistical significance should be taken very seriously.

[dddd]

Originally Posted by Mark McM

How does a flange on the top of the steerer insert force the steerer to be cut shorter? All the extra height would do is increase the spacer stack a couple of millimeters higher above the stem. I always cut carbon steerers with a generous amount of length above the stem (if nothing else this allows a little stem height adjustability), so a couple of millimeters of spacers isn't even noticeable.

It's when the stem height is adjusted to where all of the spacers are positioned below the stem, then you have the flange and the top cap step-down each stealing a few extra millimeters from the engagement of the stem on the steerer.
Also, some of today's stems are closed off at the top, so there's no option to add any spacer(s) above the stem.

[sales guy]

A big problem with steerer failure is lack of support from the inside. I only supply really long expander plugs. The short ones like the ones from Hope, Enve, KCNC and numerous others, they don't go past the stress point. This fork failed right below the stem. No spacers below it. If he had a longer plug in it would've supported the load. The plug would've gone below the stem and into the top plate of the headset. Some companies are giving longer plugs like Colnago. Luescher Teknik has been pushing this for a few years now. I've only offered longer plugs of 50-60mm long or longer if someone wants them. Deda and Columbus are offering them now as well cause of this problem.

[tv_vt]

^^^ Excellent! Haven't seen that before, but is a great idea.

[tctyres]

Originally Posted by zmalwo

It will if UCI didn't set the weight limit so low. 6.8kg is not adequate to safely construct a bicycle at all. When it comes to human life statistical significance should be taken very seriously.

I'm pretty sure no one died in this case. Statistically, you are far more likely to lose skin in a crash than die.

Anecdotally, the last death in the pro peloton was Bjorn Lambrecht a month or two ago. The youtube video shows him raising his hand as if he had a mechanical. Then he steers into a deep irrigation ditch and probably cracked a vertebrae going over the handlebars --- very sad. Again, this does not appear to have anything to do with the weight of the bike.