Carbon steerer not.. round?

Discuss light weight issues concerning road bikes & parts.
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Valy
Posts: 152
Joined: Tue May 29, 2012 11:16 pm

by Valy

Hi all,

got this new fork from a reputable online retailer and the steerer, especailly around the top, does not seem round. The pictures maybe show a very faint idea, but when you rotate it in your hands, there are definite little steps that you can feel.

I am concerned about this as all the little notches are stress risers. This is my second fork, first one the LBS cut steerer to wrong length and got me a replacement, however the sterrer was smooth as I can remember.

Please let me know what you all think. Appreciated.
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efeballi
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by efeballi

Holy moly. I think it'd be dangerous to clamp a stem there. Pretty sure the expander would also cause problems.
I would ask for another replacement.


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AJS914
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Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

To me the stem looks flared out at the edge.

Tenlegs
Posts: 285
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

Measure the fork steerer it or get it measured for roundness.
That stem looks a bit crap, is it a cheap welded stem?

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Valy
Posts: 152
Joined: Tue May 29, 2012 11:16 pm

by Valy

The stem is fine, the lack of roundness is more due to parallax that any perceptable issues. This is not a WW bike by any means guys, just came here for the advice. :D

Asked a lecturer at university and said it could even be delamination causing this. The bike shop was :noidea: about it.

Might have to do a whole RTM... through the bike shop as this is technically their copy. I could take it on but might be caught out by some questions late ron.

Third time lucky eh?

billspreston
Posts: 367
Joined: Tue Jun 30, 2009 7:40 pm
Location: CA

by billspreston

Have you taken a set of calipers and measured to determine if it is actually out of round? I'm not sure these photos tell us much.

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Valy
Posts: 152
Joined: Tue May 29, 2012 11:16 pm

by Valy

billspreston wrote:
Fri Mar 02, 2018 1:53 pm
Have you taken a set of calipers and measured to determine if it is actually out of round? I'm not sure these photos tell us much.
No, sadly don't have any lying around but wanted to.

I don't think it makes much difference, because this is something you can feel by hand. The fork on my Canyon frame was pretty round, without any of the steps you can see above for example.

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Miller
Posts: 1272
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

Does it neeed to be perfectly round? The composite steerer needs to have integrity and the stem needs to be able to clamp to the steerer securely. If those conditions apply is there really a worry.

UpFromOne
Posts: 693
Joined: Wed Apr 08, 2009 5:23 am
Location: Olympic Nat'l Park, WA

by UpFromOne

Welcome to modern day manufacturing tolerances.

I've had to put a recent carbon fork on a big lathe, to slightly turn down the beefy crown area to something more concentric.
But the stem area? I wouldn't touch that.

+1 on attempting a replacement.

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Valy
Posts: 152
Joined: Tue May 29, 2012 11:16 pm

by Valy

Maybe it does not need to be perfectly round. In the short term. What about long term though? With these irregularities there is more stress on less material and it would impact the fatigue life. I have have no idea what the safety factor is and I'd struggle to quantify what is medium and short term without seeing the test results. It's all just guesswork. Nothing is certain, but I'd want to reduce the number of things to potentially go wrong, especially if it's something that's pretty glaring like this.

FWIW I felt the original fork in the shop today and it also has these steps but defintely smaller.

UpFromOne - that's pretty odd. Could it have just been the finishing that's set it off? (assuming it was not flat)

EDIT: forgot to add, I've sent an email to the retailer today. Will update once hear back.

Tenlegs
Posts: 285
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

It does need to be round, especially where the bearings fit.
(and the correct diameter) find some calipers!

UpFromOne
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Location: Olympic Nat'l Park, WA

by UpFromOne

For sure, calipers not just around the top, but compare the top section to the middle, and to just above the crown (where it's still supposed to be 1 1/8" right before the taper).

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prendrefeu
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by prendrefeu

Get calipers. I also have a feeling it's the stem, not the steerer tube.

If it wasn't round you would have noticed as it passes through the headset.
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Valy
Posts: 152
Joined: Tue May 29, 2012 11:16 pm

by Valy

Will measure for sure. The stem is there only for reference though and the issue is not in oval stem but the "polygonal" steerer.

I think the stem is pretty safe.

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