Is it safe to ride on carbon fork with scratch

[mamil]

I have a faint line on the carbon steerer tube, there's no sign of any damage inside, is it safe to ride or should I replace it? Pics attached

 

[Webbo2]

That looks the imprint of where the stem has been. Is there a crack.

 

[Gunk]

I’d ride with that, looks fine

 

[midlandsgrimpeur]

It is very hard to tell from a pic, but the third photo down does look like a compression mark (perhaps made by the stem, as per Webbo's comment).

Rub your finger over it, if it is a compression mark you will quite clearly feel some indentation in the carbon. If it is a scratch, the tube surface will feel flat/level as normal, you will just feel a small abrasion from the scratch.

If it is compression, then it is time for a new fork.

 

[Drago]

I'd not be keen.

 

[Webbo2]

It is very hard to tell from a pic, but the third photo down does look like a compression mark (perhaps made by the stem, as per Webbo's comment).

Rub your finger over it, if it is a compression mark you will quite clearly feel some indentation in the carbon. If it is a scratch, the tube surface will feel flat/level as normal, you will just feel a small abrasion from the scratch.

If it is compression, then it is time for a new fork.

Why would compression indicate a new fork, I thought it’s extremely hard to crush a carbon tube.

 

[Drago]

Why would compression indicate a new fork, I thought it’s extremely hard to crush a carbon tube.

It is. And it has been.

 

[midlandsgrimpeur]

Why would compression indicate a new fork, I thought it’s extremely hard to crush a carbon tube.

If it is caused by an impact or over tightening, it can cause fibres to break or internal delamination, both of which are going to result in the tube cracking at some point. I have had two forks replaced previously where the headset has become loose, this caused the fork steerer tube to compress as it pressed against the bearing race. The compression caused indentations and eventually cracked the steerer tube on both occasions (two separate bikes).

 

[Mike Ayling]

Don't know but it would not be a problem with a steel fork.

 

[midlandsgrimpeur]

Don't know but it would not be a problem with a steel fork.

No, but it would have rusted by now 😉

 

[ColinJ]

Don't know but it would not be a problem with a steel fork.

No, but it would have rusted by now 😉

Like this one!

I saw the rider walking his bike after he felt the fork flop about and nearly snap off on a fast descent...

As for iffy carbon... I wouldn't trust it!

 

[midlandsgrimpeur]

Like this one!

View attachment 772569

I saw the rider walking his bike after he felt the fork flop about and nearly snap off on a fast descent...

As for iffy carbon... I wouldn't trust it!

Blimey, anyone that let's a bike get in that state shouldn't be allowed on the road!

 

[ColinJ]

Blimey, anyone that let's a bike get in that state shouldn't be allowed on the road!

I thought that when he showed me the damage!

 

[Webbo2]

If it is caused by an impact or over tightening, it can cause fibres to break or internal delamination, both of which are going to result in the tube cracking at some point. I have had two forks replaced previously where the headset has become loose, this caused the fork steerer tube to compress as it pressed against the bearing race. The compression caused indentations and eventually cracked the steerer tube on both occasions (two separate bikes).

Oh dear I might have start looking at some steerer tubes now.