Riding carbon fork without compression plug

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kkibbler
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by kkibbler

I've also read that those microscopic spheres will eventually migrate onto and into your headset, which is no good.

Art's Cyclery had this to say:
When it comes to carbon steerers there is little need for the additional friction that carbon paste provides, as it is very rare that anyone encounters a situation on a road bike where your front wheel is being pushed hard in a direction opposite to the direction you are turning the handlebars. The exception is during a crash. In this situation it’s better to have the stem slip on the steerer to lessen the amount of force transmitted to the steerer tube.

The other concern with applying carbon paste to steerer tubes is that the paste could make its way into the headset where it could grind down moving parts and possibly wear the steerer where the compression split ring interfaces with the steerer.

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Calnago
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by Calnago

That I've read and agree with. I certainly wouldn't want ANY of that crap getting into the headset bearings. When/if I use it for steertube/stem connections I just lightly put a very thin layer on the stem only so the amount on the steertube is minimal, but yeah. But I always use the compression plugs and the beefier the better as far as I'm concerned. I also like the type that extend the whole stack height of the stem right one down past the top bearing of the headset.
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DamonRinard
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by DamonRinard

Good comments.

@11.4, your summary is right on. In my experience slip is less common, while crushing happens more often. The scary part is a stem's clamp can stress the fork and it seems fine until additional stress overloads it. This is where using the right expander, and as you point out, positioning it properly in the fork to match the stem clamp, can help.

@Calnago, I worked at Trek when Big George's steerer sparked the engineering investigation that led to the recommendations you mentioned. They're generally good recommendations, including the warning against FSA stems - they were fork killers. (Since then FSA has changed most of their stem clamps.) At that time most Trek bikes, including George's, had aluminum steerers.

The recommendation against carbon paste was a few years later, when more Trek steerers were carbon.
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Wingnut
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by Wingnut

UpFromOne wrote:Wingnut, is this the Schmolke plug?

Wingnut wrote:Image


It is...from Bike24.

PrimO
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by PrimO

Wrong thread

alcatraz
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by alcatraz

300km ridden now without any problem UNTIL I hit this huge pothole.

Seems the stem crept up a little because there is a slight play in the headset now. Steerer tube no problem. Solid as a rock.

I don't know if a compression plug would have avoided the issue. No biggie, I wasn't stranded because of it. I'll bolt it back down tomorrow...

Anyway, the solution, I think, is not to mount the plug but just avoid potholes. I'm angry with myself for not seeing it but it was dark.

/a

Edit: I'm not using carbon paste

Edit2: Now readjusted the stem and the headset is without play and smooth as butter.
Last edited by alcatraz on Fri Sep 09, 2016 11:27 am, edited 1 time in total.

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Kayrehn
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by Kayrehn

Just a thought - since things like the Extralite ultrastar doesn't exert outward force along the depth of the stem clamp area, isn't it redundant for the purpose of preventing a possible steerer tube collapse?

I've used it for years anyway, and nothing happened as yet all this while, so I'm going ahead with my experiment with a bolt-less steerer tube carbonice cover after fixing up the stem and removing the plug.

alcatraz
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by alcatraz

Kayrehn wrote:Just a thought - since things like the Extralite ultrastar doesn't exert outward force along the depth of the stem clamp area, isn't it redundant for the purpose of preventing a possible steerer tube collapse?

I've used it for years anyway, and nothing happened as yet all this while, so I'm going ahead with my experiment with a bolt-less steerer tube carbonice cover after fixing up the stem and removing the plug.


Yeah I also noticed that the large 50mm deep compression plug I'm using isn't running along the whole stem. Just the upper edge and ending at around middle of the stem (due to tube sticking out 15mm above). That means that the weakest (first breaking) point of the steerer tube, being the bottom of the stem, is not "structually supported" with or without the plug. Seems redundant... but thats just my own theory.

/a

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BRM
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by BRM

If something needs support its the upper end/outer part of the forktube. That section is more vulnerable for deformation and cracking than the piece under it.



(when reacting on the last post in a topic, quoting is not necessary)

alcatraz
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by alcatraz

When browsing the internet for pictures of damaged carbon forks, the minority portion of the ones I found that were of a damaged steerer tube had either:

1. what you are saying, compression damage from the stem with a crack going along the tube.

2. a severed steerer tube with the breaking point at the lower stemline. These were pictures of mtb forks.

The pictures forum posts/articles were discussing carbon quality/construction and stem overtightening/sharp edges (because certain stem models were more prominent). They were not centered on compression plugs and had me to assume that the damaged forks all had compression plugs (possibly incorrectly) installed.

/a

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