Repairing scratched carbon steerer tube

andyeb
andyeb Posts: 407
edited June 2013 in Workshop
While working on the headset of my bike, I managed to put a vertical scratch in the carbon steerer tube while removing a circlip to clean up excess grease and dirt. :cry:

There seem to be two schools of thought with regard to damaged carbon fibre:

- throw it away and replace, especially for high stress components like seat posts, handlebars, forks and steerer tubes.

- carefully repair it

Someone I know suggested smearing epoxy resin into the scratch to repair it. But this isn't a technique I've found elsewhere online.

I've been looking at the cost of replacing the fork and steerer tube, but it is around half the cost of replacing the bike with a brand new one. Given the bike has probably done around 10,000 miles, most key components are wearing out and was only entry level to start with, a whole new bike is probably the most economic approach. However finances do not currently stretch to this :( so wondering what could be done to salvage that scratched steerer tube.

Any thoughts/ideas/suggestions please?

thanks,

Andrew

Comments

  • keef66
    keef66 Posts: 13,123
    Pictures would be useful. From your description to me it sounds like a superficial scratch and you've probably got away with it. You mention a circlip; do you mean the crown race that sits at the bottom of the steerer?
  • dgunthor
    dgunthor Posts: 644
    photo would help but sounds superficial unless it's deep. carbon fibre is layers of carbon and epoxy resin, so resin fix should be fine assuming you have only scratched the resin part
  • andyeb
    andyeb Posts: 407
    keef66 wrote:
    Pictures would be useful. From your description to me it sounds like a superficial scratch and you've probably got away with it. You mention a circlip; do you mean the crown race that sits at the bottom of the steerer?

    Thanks guys - I'll take it all to pieces again and take some photos and post back.

    With regard to the circlip - it's a kind of cone-shaped washer which sits underneath the bottom crown race, the inside edge of which is bevelled. Initially I thought it was just a specially shaped circular washer (i.e. with no gap in it), but the gap was round the other side of the steerer. Hence when I came to lift it off to remove it to clean up the excess dirty grease in the area, the sharp inside of the circlip by the gap scored the steerer tube and I didn't realise until I had moved it several inches and I walked round the other side of the bike to investigate the unexpected extra friction.

    Got to wonder who in their right mind would have specified a circlip in that scenario - especially the rough inner edge and given the risk and implications of scoring the carbon fibre steerer.
  • Bozman
    Bozman Posts: 2,518
    I splintered a carbon steerer once, probably 5mm/1mm and 50mm in length, that had zero effect. A bit of glue, then wet and dry and you couldn't even tell.
  • keef66
    keef66 Posts: 13,123
    Hmm, I'm just in the process of acquiring one of Westbrook's CR1-SL frame and fork bargains. Carbon fork and steerer and I'll have to fit the headset. I will be very careful with the split crown race!
  • dennisn
    dennisn Posts: 10,601
    If all it took was a small scratch to ruin a carbon part then carbon parts wouldn't even exist.
    I think you've sort of fallen into a sort of thing like going to the doctor and expecting the worst only to find out all you have is a slight sore throat. In other words a bit of overreation.
  • andyeb
    andyeb Posts: 407
    keef66 wrote:
    Hmm, I'm just in the process of acquiring one of Westbrook's CR1-SL frame and fork bargains. Carbon fork and steerer and I'll have to fit the headset. I will be very careful with the split crown race!

    :D makes me feel better knowing that someone else at least learned something by my mistake!
  • andyeb
    andyeb Posts: 407
    dennisn wrote:
    If all it took was a small scratch to ruin a carbon part then carbon parts wouldn't even exist.
    I think you've sort of fallen into a sort of thing like going to the doctor and expecting the worst only to find out all you have is a slight sore throat. In other words a bit of overreation.

    I take your point. But if the steerer fails on me at 45mph downhill, the doctor will have me as a kit of parts to put back together ;)
  • andyeb
    andyeb Posts: 407
    Bozman wrote:
    I splintered a carbon steerer once, probably 5mm/1mm and 50mm in length, that had zero effect. A bit of glue, then wet and dry and you couldn't even tell.

    Based on what I've been reading online, you might want to periodically disassemble that and check it's OK.

    Here's what someone else did to repair a split steerer: http://forums.roadbikereview.com/compon ... -5203.html
  • dennisn
    dennisn Posts: 10,601
    andyeb wrote:
    dennisn wrote:
    If all it took was a small scratch to ruin a carbon part then carbon parts wouldn't even exist.
    I think you've sort of fallen into a sort of thing like going to the doctor and expecting the worst only to find out all you have is a slight sore throat. In other words a bit of overreation.

    I take your point. But if the steerer fails on me at 45mph downhill, the doctor will have me as a kit of parts to put back together ;)

    If you have no confidence in carbon why would you buy it? All it takes is a scratch and it's desroyed????? Way huge overreaction.
    You don't have to use carbon anywhere on a bike if you have no faith in it's durability. Frames, rims, bars, components, seatposts, forks, etc. all come in alloy. So if carbon has got you paranoid then I would urge you to go metal.
  • Bozman
    Bozman Posts: 2,518
    andyeb wrote:
    Bozman wrote:
    I splintered a carbon steerer once, probably 5mm/1mm and 50mm in length, that had zero effect. A bit of glue, then wet and dry and you couldn't even tell.

    Based on what I've been reading online, you might want to periodically disassemble that and check it's OK.

    Here's what someone else did to repair a split steerer: http://forums.roadbikereview.com/compon ... -5203.html
    It's a surface splinter not a crack
  • mamba80
    mamba80 Posts: 5,032
    is it a LOOK bike? if so i ve also done that with the cir clip, ages ago and that steerer tube is about twice the thickness of a normal fork... i worried for while and forgot about it!
  • andyeb
    andyeb Posts: 407
    mamba80 wrote:
    is it a LOOK bike? if so i ve also done that with the cir clip, ages ago and that steerer tube is about twice the thickness of a normal fork... i worried for while and forgot about it!

    Sadly not - it's a cheap-and-rather-nasty Jamis, with the harshest ride known to mankind ;). Never again.
  • wishitwasallflat
    wishitwasallflat Posts: 2,927
    I know it's none of my business as I can't really offer any advice as I have never had a C steerer fork but having followed this thread I would still love to see a picture of the damage out of pure curiosity - it might also help for those who find this searching in the future to see the extent of the damage.
  • Monty Dog
    Monty Dog Posts: 20,614
    Fork steerers are hugely over-engineered because of the stresses put on them near the crown - if the scratch is on the section under the stem clamp then you'll have few worries as the steerer bung supports it internally.
    Make mine an Italian, with Campagnolo on the side..
  • Yossie
    Yossie Posts: 2,600
    Load of tosh - it'll be fine. Slap it back together and no worries. If it was that fragile it wouldn't be used at all. TDV smashed the good bike off the top of the car (standing up bike rack thing - bike was ripped off and was found lying flat on the roof of the car) using a car park wall - its got EC90 carbon bars and SLX forks with the carbon steerer - that was 5 years ago and it hasn't played up at all, so a minor scratch isn't going to make any difference at all.

    We all know that the only thing that destroy carbon is rain.

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