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First time working with carbon. Bought a longer compression plug, because it came with a very small one, not even covering the whole height of the stem.

I tightened it to 7 Nm. Took a while… Made already screeching noises inside the steerer tube. I loosened it (still possible with an Allen key). Checked for damage but beside the imprints of the plug inside the steerer there are no cracks.

I tightened at 6 Nm again. Still some small screeching noises. not as loud as with 7 Nm but still… Is this normal? The plug does no noise if I tighten it outside the tube…

The manufacturer wrote 9-12 Nm on their plug!!

I tried two torque wrenches, a cheap one and an expensive one. Maybe they don’t check correctly because they can’t really measure the applied torque on the plug? I don’t know much about torque wrenches apart from how to use them on regular screws. The turns I needed to tighten it seemed very much for 6 Nm… same problem with the manufacturers plug.

Also if there is no visible damage, still safe to use?

Edit: imprints - those white ones. These small silver studs that are all over the plug. They get pressed into the steerer tube and leave small white marks - I thought this is pretty normal, as they are made to prevent slipping? At least the have been caused by the manufacturer plug too before. Maybe not as hard… Otherwise the plug would be smooth I guess? But I am no pro. Measurement of my torque wrench is 2,5-25 Nm. Plug is a Deda steerer plug, for carbon steerers. I tightened it without the stem on the steerer, hope this is correct. Thank you for helping me.

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    beside the imprints of the plug inside the steerer?!?! That seems concerning. Can you post pictures of the inside of the tube, perhaps with a light illuminating the inside so whatever the imprints are might be apparent? Imprints into a carbon steer tube doesn't sound good - I can't imagine an "imprint" that wouldn't be damaging. Surface scratches might be OK, but "imprint" implies to me some sort of denting of the surface. Jun 4, 2023 at 18:55
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    You are tightening the plug with the stem already mounted on the steerer tube, right?
    – Robert
    Jun 4, 2023 at 21:15
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    Hmm, maybe it doesn't matter that much. But what you can try is this sequence: 1.tighten the plug just enough to allow proper bearing adjustment (5-6nm); 2. tighten the stem bolts to the recommended torque; 3. and only now, after the stem is secured and supporting the steerer tube from the outside, tighten the plug to its full recommended torque. If the type of headset, stem, and plug you have allows for this.
    – Robert
    Jun 4, 2023 at 21:23
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    Also check if the plug is compatible with carbon steerer tubes.
    – Robert
    Jun 4, 2023 at 21:25
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    Also see this related question: bicycles.stackexchange.com/questions/75510/…
    – Robert
    Jun 4, 2023 at 21:28

1 Answer 1

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I have rode a bunch of different bikes with different styles of compression plugs and I have learn a few things and sometimes you don't need to torque it down all the way to what the makers says.

If you are at 6 Nm, and everything feels snug and there is no play then you can torque down the stem. The role of the compression plug is to compress the "Fork, headset, spacers and stem" but the stem is what actually locks everything together. I always go by the rule of how the bearings feel, because you will hurt them if you over or under tight them.

Check all clearances sometimes when torqueing the direction assembly, the steer tube will make contact with the compression bolt and you will need to add a spacer or chop the steer tube. I have witnessed people pulling those "spider/flower" type compression plugs all the way up, and stripping the old long ones that went all the way to the bottom of the crown, because the compression plug was making contact with the steer tube. A good indicator of this is when the compression bolt is super tight and the headset is still loose.

Also, it would not hurt to smear some lube where the bolt seats in the compression plug's cap. Use something compatible that won't degrade carbon fiber resin. Check your work after a few rides, and investing thread locker is a good idea a bottle last for years.

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