Hi,

After my first test ride and a check of my bike, headset am so on, I noticed this mark about 1cm on the top of the steerer tube, at the stem level.
Is that damaged or safe to keep riding with that ?
I wonder if the carbon quality is not involved in that change and suspect the stem pressure might have caused it.
I am thinking to go to the LBS to make sure it is safe. No marks or cracks further below.


Thanks for your advice.

John

Yes it's damaged.

This type of damage can happen two ways.

1- the expander plug was overtightened, stressing the steerer radially (like over inflating a tire) and cracking the steerer.
2- an imperfectly formed stem was tightened distorting the tube and cracking it. When thin king about this consider an egg. If you squeeze it very evenly between your two palms it's incredibly hard to break. But if you don't cup it well or dig in a finger it cracks ---- like an egg.

If it is stem damage, most likely it was on a stem that sat very high, so the clamping force was highest at the end of the tube. This is why many fork companies suggest (insist?) that you keep at least one spacer of 5mm or so above the stem, so it's clamping fully on the tube, and not at the end.

So, yes it's damaged. Whether to continue to ride it or not is a judgement call. If you decide to ride it, switch some spacers to push the stem down away from the damaged zone, and use more spacers on top. Tighten the plug only enough to do it's job, and consider buying one with a solid area below the top to support the end of the tube.

Then mark the extent of the damage, and check it from time to time to make sure the crack isn't growing.

BTW - if this is a new bike set up by the shop, I believe they owe you a fork (if you never touched it), but that's between you and them.

Thanks for your answer and advice FB.
I don't have the feeling I did overtighten knowing I used a torque wrench. Will check with my lbs.

Squirt some thin CA in there and clamp it real quick. J

It looks like the stem was clamped very high on the steerer tube, with maybe half the stem height above the steerer. That's not good. There were too many spacers for the cut height of the steerer?

From another steerer damage thread, here's some example photos from Bianchi.

Damaged - crushed.


~~~

Not damaged, showing normal surface markings from the stem. (The circular mark is from the milled hole in the front of the steerer clamp.)

The steerer tube extended above the top of the stem, so a spacer would have been used between the top of the stem and the end cap.

If the steerer is long enough I would suggest that you cut it below the crack and then reinstall with a 5mm spacer above the stem.