Carbon failure at Tour du Doubs sprint

[tctyres]

Originally Posted by sales guy

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.

Great, thanks! I ordered one.

[sales guy]

Originally Posted by tv_vt

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

The top one is a Colnago one and it like 80mm long.
Then a Hope, a generic one used by a bunch of people, then an Enve one.
The ones I bring in are 60mm long but I do offer the 80mm ones for people planning on a taller spacer stack.

Given a stem is only 35 to 40mm tall, add a few spacers, the ones I use will put it into the headset depending on spacers stack. Leuscher Teknik has shown some headset top plates that have damaged steerers. All to save a few grams, people are putting themselves in harms way if the steerer fails. And they do!

[dddd]

Originally Posted by 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.

I noticed that on all of these flanged expander plugs, not only does the thickness of the flange itself moves the end of the steerer below the top end of the installed expander plug, but what looks like a length of the top cone also spaces the gripping/support sleeve below the end of the steerer. And of course this space can be added to not only the flange thickness but also to the step-down of any top cap that has such a feature to potentially move the internally-supported length of the steerer further down from the top of the stem clamp.
All of this can force the top of the support sleeve well below the top of the stem (plus a bit yet further down considering the needed headset-tensioning clearance) on installations lacking a spacer above the stem.

So I would really prefer to see all such expander plugs position the gripping/support sleeve within a mm or two of the end of the bare steerer, and with the top cap having a purely flat underside profile.

I don't believe that a sufficiently overwhelming majority of those who set up or subsequently adjust these current setups (which may add un-clamped space within the stem clamp above the end of the steerer) are fully cognizant of these implications of riding without any spacer(s) above the stem, and as such I consider these to be dangerously defective from any reasonable liability perspective.
I would temper/amend the above (and below) if/when I see any published research that suggests that the loss of roughly 5-6mm of clamping length (of existing 35-40+mm stem clamping lengths) does not seriously compromise the integrity of the installed stem/steerer assembly.

That some of these expander plugs are offered in longer lengths is very good, and would appear to have the potential to prevent catastrophic separation of the top end of the steerer, but in terms of their seeming potential for slightly increasing the the likelihood of a faulty/dangerous installation, I think this is nuts.

I also think that there perhaps needs to be rigid standards for the ID of carbon steerers into which these expander plugs are used, to facilitate (and in addition to) the elimination of the potentially non-gripping space within the stem clamp that the current designs impose. Perhaps such standards already exist(?).

After further consideration, I think that it might be simplest for all top caps to include some minimum of built-on spacer (perhaps 5 or 6mm) sufficient to accommodate the potential combined loss of clamping length (which should be defined as a standardized maximum distance) resulting from the upper few mm of the expander plug plus any step-down of the top cap (that might typically be used to allow a flush top cap bolt head).

Has a top cap with a built-on spacer perhaps been done already(?), I don't know.

[Fivethumbs]

A couple of years ago this exact same thing happened on a Diamond Back in the Tour of California. The incident was caught on video but there was never any follow up information. It seemed like the the incident was quashed and everyone acted like it never happened. I see riders crash all the time in races and jump back on their bikes. Those crashes can likely have an effect on the integrity of the bike.

[tony_mm]

Originally Posted by Fivethumbs

I see riders crash all the time in races and jump back on their bikes. Those crashes can likely have an effect on the integrity of the bike.

Definitely! That‘s also a reason why the Pro teams sell all their bikes after one season....

[m_sasso]

I have been using these inexpensive Neco C286GCL expanders, not quite as long as the Colonago, however the supported area under the stem clamp is much larger than the vast majority of plugs and exceeds the stack height by a good margin of any stem I have worked with.

[tctyres]

This is the Leuscher Teknik explanation: https://www.youtube.com/watch?v=8bSnbjHiFXc

[mcteague]

Originally Posted by tctyres

This is the Leuscher Teknik explanation: https://www.youtube.com/watch?v=8bSnbjHiFXc

He just uploaded a more recent video about this.

https://m.youtube.com/watch?v=muukpjzb5Jw

And one from durianrider. He can be a bit much but this video is pretty much spot on.

https://www.youtube.com/watch?v=vxoozD4WdJk

Tim

[tctyres]

Originally Posted by mcteague

He just uploaded a more recent video about this.

https://m.youtube.com/watch?v=muukpjzb5Jw

And one from durianrider. He can be a bit much but this video is pretty much spot on.

https://www.youtube.com/watch?v=vxoozD4WdJk

Tim

Thanks!

durianrider is a bit of a character. I had to fast forward through that, but the comment on where the pro cyclist is looking to land is dark and funny.

[sales guy]

I don't know who this Durian guy is, but it bugs me he says BianCHEE. And I've been talking about the small expander plugs for years. I never ever use them. I have a huge bag filled with them cause they absolutely suck.

[mcteague]

Originally Posted by sales guy

I don't know who this Durian guy is, but it bugs me he says BianCHEE. And I've been talking about the small expander plugs for years. I never ever use them. I have a huge bag filled with them cause they absolutely suck.

The Specialized plugs look nice and are cheap at $10!



Tim

[dddd]

Originally Posted by mcteague

The Specialized plugs look nice and are cheap at $10!



Tim

Not just cheap and long, but the support extends much closer to the top flange as well.

I would put in a rec for Cervelo's glued-in (and very light) thin aluminum tube, as long as it is glued in well (since I had to re-glue one once).
Extends over the "working" length of the steerer and uses the simple old star-fangled nut that never slips.
I'm actually surprised that all of the bike makers didn't go this route many years ago!

[Veloo]

Origin8 has one.
http://origin8.bike/product/fusion-e...ion-plug-35895

So does Eclypse, which Urbane carries here in T.O. They said it is about 6 cm long.
https://www.walmart.com/ip/Eclypse-B...-6mm/184630719

[unterhausen]

Originally Posted by dddd

I'm actually surprised that all of the bike makers didn't go this route many years ago!

what I'm surprised about is that fork manufacturers don't just make a steerer that can't be broken by bad mechanics. It's going to happen, at all levels of cycling.

[zmalwo]

The specialized ones barely covers the length of your stem clamp. Get the Colnago one. 80mm ensures you to be able to have a few spacers for those not so cut steerers.