Carbon fibre repair- end result

Tb2121 Posts: 73
edited May 2013 in Workshop
Just thought i'd share my experience of fixing a specialised roubaix with a carbon fibre repair kit.
Got the bike from my Uncle who threw the bike down the road one winter day- cracked the carbon at the down tube near to the bottom bracket.
He was paid out by the insurance and so thought i'd upgrade my bike by taking the bike off him and fixing it. I had a couple of quotes of £200, but thought i'd buy a £35 kit and try it out.

The results are attached- i've kept the new carbon fibre at a different finishing direction to the original- so that people will be able to tell a repair has been made.
Reason being is that i'm not going to sell it, but it may get nicked and I don't want anyone to buy a bike and not know that its been repaired.

The repair has held up now for 750 miles, been through London pot holes on the daily commute, and no issues have occurred.

The repair itself was fairly easy, the kit had decent instructions and if you followed them you'd find it fairly easy.
The only problems I had was where to put the unused adhesive as it really is foul stuff, and when unwrapping the carbon layers the sheets of fibre wrap take some pulling off. I also found that wrapping the carbon could get messy, and if you are anal about detail you only have one chance- so best take your time!

Initially I was wary of whether the repair would hold, but the more i've used it the more confident I am in it, and when talking to engineers in the carbon fibre business they too put my mind at rest as they feel that as long as you add enough layers, and go far enough above and below the fault then you should be Ok.

The key elements that I have learnt from doing this are:
Ensure you carbon wrap a good way up and down from the crack- at least 3.5cm either side of the crack.
If its at a stress point- probably best not to do it yourself.
Follow instructions to the letter- use at least 3 layers of carbon, and don't rush the job.

Other than that i would definitely do it again if a bike came up that was worth repairing.


  • denniskwok
    denniskwok Posts: 339
    Good stuff, makes me want to try it out for myself. Where did you get the kit from and how did you go about vacuum bagging and applying pressure to the patched area?
  • andy_wrx
    andy_wrx Posts: 3,396
    Here's another one ... me-repair/

    Yeah, I'd have a go, particularly on a mainframe tube although I'd be less keen on a chainstay, say
  • ricky1980
    ricky1980 Posts: 891
    that is very interesting. what's the kit? also what fibre was in the kit and the resin? I assume you basically soaked the sheets in resin then applied onto the frame therefore there is no vacuum bag and pressure applied to the patch?

    to the previous question, about how you can apply pressure. you can get one of those old blood pressure gauges which pumps around into a sac that wraps around your arm. that stuff can go to fairly decent pressure as well.

    Road - Cannondale CAAD 8 - 7.8kg
    Road - Chinese Carbon Diablo - 6.4kg
  • denniskwok
    denniskwok Posts: 339
    Looking at some of the kits you can buy, it seems that you lay and cure one layer at a time and pressure is applied by wrapping the area to be cured in a plastic which is heat shrunk.