Cracked head post?

[lux666]

Hi guys! Today I have noticed small crack on carbon fork head post (boardman hybrid pro 2016). First I am not sure if its 100% cracked and not sure how to check it, but I can feel under my nail that its a bit deeper than rest. Can I still use it or should I change it? As replacement I can only find planet x london road fork or would you suggest something different?
Many thanks for any help.

 

[rogerzilla]

Don't ride it if it really is a crack and not just a light scratch. Go to Halfords and claim under the warranty (assuming you are the original buyer).

A broken steerer is one of the things that you absolutely do not want to happen. A broken fork blade is quite survivable in comparison.

 

[biggs682]

Have you had from new ?

 

[lux666]

second hand

 

[lux666]

so I do need new one, which one would you recommend ?

 

[Yellow Saddle]

That doesn't look like a crack to me but it is easy to check. It is a pity the photo doesn't show the fork orientation. Nevertheless, a crack will quickly show up under strain.

If you have a bench vice, do this:

1) Clamp the steerer, with the fork horizontally, in the bench vice BELOW the jaws. The clamping will be firm but not crushing. The bit below the jaws is a natural place for a tube like a steerer. Clamp it so that the "crack" is visible i.e. at the top.
2) Manipulate (flex/bend) the fork.
3) Observe the crack. If it is a crack, there will be opening and closing of the line and perhaps even some sounds. You could put some soapy water on the area or drip it on whilst you manipulate it, that should, if it is a crack, show up as agitation of the fluid.

The reason I say it isn't a crack is because a fibre-mat composite like carbon fibre, fibreglass or kevlar composite doesn't crack like that. The crack doesn't travel longitudinally. Secondly a steerer's forces would cause a crack diagonally across the steerer, in the place dictated by fore/aft movement of the fork. That doesn't look like it.

I bet it isn't a crack. But then, I'm a plumber, I would say that.

 

[biggs682]

Aside from doing as @Yellow Saddle suggests you could try something like this https://www.gas-uk.co.uk/crack-detection-spray-set.html i have not used it on carbon before but have used similar products with good success

 

[rogerzilla]

If you need a replacement, you need to measure the blade length and offset and get something close. Blade length is measured vertically from fork crown race seat to the axle line projected from the centre of the axle slot in the fork-ends. Offset is the distance between the centreline of the steerer and the centre of the axle slot. It is not especially easy to measure offset.

All new threadless forks have massive long steerers, designed to be cut to length, so that's something you don't have to worry about these days. (With threaded forks you have to get the right steerer length AND the amount of the steerer that is threaded is important, because you can't just buy the longest steerer and pack spacers under the headset locknut).

Nearly all road racing bikes have an offset of 43-45mm. Hybrids are probably similar, provided they have 700c wheels too. If the bike originally had a little more offset, say 47mm, fitting a 45mm offset fork will make the steering a bit slower (more inclined to straight-ahead, easier to ride hands-off) but it would be perfectly rideable.

 

[lux666]

That doesn't look like a crack to me but it is easy to check. It is a pity the photo doesn't show the fork orientation. Nevertheless, a crack will quickly show up under strain.

If you have a bench vice, do this:

1) Clamp the steerer, with the fork horizontally, in the bench vice BELOW the jaws. The clamping will be firm but not crushing. The bit below the jaws is a natural place for a tube like a steerer. Clamp it so that the "crack" is visible i.e. at the top.
2) Manipulate (flex/bend) the fork.
3) Observe the crack. If it is a crack, there will be opening and closing of the line and perhaps even some sounds. You could put some soapy water on the area or drip it on whilst you manipulate it, that should, if it is a crack, show up as agitation of the fluid.

The reason I say it isn't a crack is because a fibre-mat composite like carbon fibre, fibreglass or kevlar composite doesn't crack like that. The crack doesn't travel longitudinally. Secondly a steerer's forces would cause a crack diagonally across the steerer, in the place dictated by fore/aft movement of the fork. That doesn't look like it.

I bet it isn't a crack. But then, I'm a plumber, I would say that.

Many thanks for advice! First I want to apologise for my bad English and explanation to everyone, its not my first language. The crack is located at the bottom front of the steerer.

 

[Yellow Saddle]

Many thanks for advice! First I want to apologise for my bad English and explanation to everyone, its not my first language. The crack is located at the bottom front of the steerer.

No need to apologise for anything. Besides, your English is better than that of plenty of English natives' language on here, particularly the ones who lazily type rubbish messages, with fat fingers, on their phones and can't be bothered to correct spelling or use punctuation and capitalisation, yet expect us to give them comprehensive answers.

 

[lux666]

That doesn't look like a crack to me but it is easy to check. It is a pity the photo doesn't show the fork orientation. Nevertheless, a crack will quickly show up under strain.

If you have a bench vice, do this:

1) Clamp the steerer, with the fork horizontally, in the bench vice BELOW the jaws. The clamping will be firm but not crushing. The bit below the jaws is a natural place for a tube like a steerer. Clamp it so that the "crack" is visible i.e. at the top.
2) Manipulate (flex/bend) the fork.
3) Observe the crack. If it is a crack, there will be opening and closing of the line and perhaps even some sounds. You could put some soapy water on the area or drip it on whilst you manipulate it, that should, if it is a crack, show up as agitation of the fluid.

The reason I say it isn't a crack is because a fibre-mat composite like carbon fibre, fibreglass or kevlar composite doesn't crack like that. The crack doesn't travel longitudinally. Secondly a steerer's forces would cause a crack diagonally across the steerer, in the place dictated by fore/aft movement of the fork. That doesn't look like it.

I bet it isn't a crack. But then, I'm a plumber, I would say that.

Hi, I have check it today as you told me. In some of bending exercises I have put my body weight on it (110kg) and this "crack" is not moving,opening, or making any sound. What would be next check that you would recommend? Crack detector spray as biggs682 suggested? or take it to halfords and ask them for opinion?
Thanks

 

[Yellow Saddle]

Hi, I have check it today as you told me. In some of bending exercises I have put my body weight on it (110kg) and this "crack" is not moving,opening, or making any sound. What would be next check that you would recommend? Crack detector spray as biggs682 suggested? or take it to halfords and ask them for opinion?
Thanks

You've confirmed that it is not a crack. Go for a ride, drink a beer.

I won't trust Halford's opinion. Not that I don't trust the company, but the individual you speak to will have no means to do such a test and, the company will avoid having to give an opinion other than one of extreme caution, lest they be sued by idiots.

It isn't a crack. Carbon is extremely noisy when it cracks. You'll know when things go south long before you hit the deck. The detector spray is unnecessary, expensive and you'll never use it again.

 

[lux666]

Many thanks for help! I have learned a lot about carbon in last 24 hours
Amazing forum BTW