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As per the title: I've had my bike serviced by a bike shop, who helpfully tightened up the stem cap and pinch bolts on my headset. I rode it approx 15 km (9 miles) and I noticed some play in the headset was reintroduced. I went through the usual steps of tightening it again (loosening off the pinch bolts, then checking wheel/bar alignment, then tightening the cap bolt, then re-tightening the pinch bolts), however I noticed the ridiculous amount of tightening on the pinch bolts. So much so, I could barely remove the bolts and nearly rounded them off.

I'm concerned that there's some damage to the steerer tube, as the pinch bolts were only rated to 5NM and they were clearly much tighter than that, and the play in the headset had returned in a short distance. Attached are some photos of the tube, where I can't see any obvious cracks, but you can see where the stem has been tightly mounted. (The top section that is dark, with an oval imprint, is where the stem has been mounted very tightly).

enter image description here

Without returning to the shop that bungled the job, is there a way to tell if this is safe to ride?

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  • Without returning to the shop that bungled the job, is there a way to tell if this is safe to ride? Would you trust whatever answer they gave you?
    – Andrew Henle
    Jan 28, 2019 at 0:21
  • Do you have another LBS in range, for a second opinion?
    – Criggie ♦
    Jan 28, 2019 at 6:52

2 Answers 2

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In practical terms, it's impossible to tell for sure in a case like this. It's probably fine, but there's no way of knowing absolutely via visual inspection.

The surface indentations from the stem windows do occur naturally even with consistently correct torque on the fasteners. They're pretty normal to see.

It would be a good idea to get it as clean as possible so it can inspected closely for cracks or delamination. If you find any of that, it's toast.

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  • They might also be deposits of grime or even the slightest indentation visually enhanced by such deposit. On the other hand, the sturdy metal expansion inset in the steerer tube will counter compression from the outside. Even to the degree of shearing off the bolt-heads on the stem.
    – Carel
    Jan 29, 2019 at 18:43
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Simplfied, Carbon Fibre is strands embedded in a cured resin. That oval looks like a mark on the outer layer of resin, and not a cut through to any of the fibres below. Try running your fingernail over the edges and lines, and see how deep any damage is.

Get a second opinion from someone else in person. Remember your worst case here is a new fork, and the bike is okay to keep riding.

Then if it seems appropriate, seal up the area with a very thin coat of resin, or clear nail varnish (Do consult others for ideas here.) This slight increase in thickness will help.

Finally when you do reassemble, use carbon fibre assembly paste, even if your stem is something else. This will help increase friction between stem and steerer, and you won't need as much tension.

If that doesn't help, then its possible your stem is slightly distorted and not able to clamp down enough. I've managed to successfully file a small amount off an aluminium stem to make it pinch up better, but not if its made of carbon fibre. CF-wrapped aluminium could be filed okay.

Another option is to move a spacer from below to above the stem, making it clamp down on a slightly different area of the spacer.

Separately - if the LBS has damaged your bike then you may have a legal claim against them for poor work. This is totally dependent on your location in the world and the laws in that place.

For me I know I have to give them the opportunity to "make right" but I could insist that someone else works on the bike, not the original mechanic.

This section really is more of a law.SE question.

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    Agree with all this. Also, with carbon steerers, it's a good idea to have a solid "bung" in the steerer tube to support the tube when the stem is clamped down on it. A lot of these bungs are cut down (or omitted) in the interest of weight savings, but this situation illustrates why that might be a false economy.
    – Adam Rice
    Jan 28, 2019 at 19:41

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