Cracked carbon frame

[Mike Sales]

Above the WEST System is mentioned. This stands for Wood Epoxy Saturation Technique, developed by the Gougeon brothers. I learned my composite techniques from their book, The Gougeon Brothers on Boat Construction.
There is some beautiful workmanship pictured in it, as well as much helpful advice.
I always like to finish the work with a coat of polyurethane varnish, or paint, to protect the epoxy from UV light.

[alexnharvey]

Very unhelpful members saying throw it in the bin and buy steel
The poster asked for help nothing else

Indeed. Not a very nice welcome for a new member either. It's a pity some people feel the need to peddle their own prejudices about carbon frames at any opportunity.

[slowster]

Very unhelpful members saying throw it in the bin and buy steel
The poster asked for help nothing else

Indeed we have a roll call of shame in this thread of people peddling their own prejudices (the steel brigade) and opining that it couldn't be fixed (based on what knowledge of composite repair one wonders).

I find it quite useful when people who pretend knowledge they don't have, prove it by posting something which is clearly rubbish, especially if they make a habit of it. It means that you don't have to waste time whenever you see their posts: you know that they are unlikely to contain information that is correct or useful.

[kylecycler]

Just watched this, thought it should help the OP. 'ETOE' - Martin Grey, the German frame painter - repairing typical chainstay damage due to a dropped chain. Not quite the same damage but same principles. Sanded the area, applied resin, carbon fibre strips then perforated shrink tape which he then heated causing it to shrink, and that applied pressure same as a vacuum bag. Sanded smooth and ready to paint.

You'll also see earlier in the video he plugged derailleur cable holes with carbon rod as the owner wanted to just have Di2, filled them with carbon rod and inserted an inner tube inside the frame then inflated it to apply the pressure. The more relevant repair starts at 14:40.

[youtube]GYKyqAd8qhQ[/youtube]

[kylecycler]

Here's another one pretty much exactly what the OP needs to do, same principles as above. Not quite as slick but he clearly knows what he's about if you watch it all the way through:

[youtube]sJjFxyZMIlo[/youtube]

[kylecycler]

Just to say, it's easy for me to sit here and try to post helpful videos, quite another for me to do it myself, but it really does look quite straightforward, if a bit daunting, and the finished result is sound and invisible provided it's done properly.

[Mike Sales]

Just to say, it's easy for me to sit here and try to post helpful videos, quite another for me to do it myself, but it really does look quite straightforward, if a bit daunting, and the finished result is sound and invisible provided it's done properly.

I found that a dry rehearsal, without resin, was very useful.
The middle of a sticky and complex sequence is no time to find out that you had visualised the procedure inadequately, and there is an unforeseen difficulty.

[kylecycler]

Just to say, it's easy for me to sit here and try to post helpful videos, quite another for me to do it myself, but it really does look quite straightforward, if a bit daunting, and the finished result is sound and invisible provided it's done properly.

I found that a dry rehearsal, without resin, was very useful.
The middle of a sticky and complex sequence is no time to find out that you had visualised the procedure inadequately, and there is an unforeseen difficulty.

I watch plastic modelling videos on YouTube (even though I've never built a plastic model since I was in my teens!) - the workmanship is fantastic - and they do that all the time, right enough - a 'dry run'.

[gregoryoftours]

I suspect I'm going to regret posting a photo of possibly the ugliest repair anyone's ever inflicted on their bike.
DSC_0019[1].JPG

I was expecting something messier than that, to be honest. It's interesting to know how you did it and how it's held up too.

[Ke1th]

I had a derailleur hanger fail on my carbon bike. Derailleur and chain wrapped up and end result was a snapped seatstay. I looked at many DIY repair videos and decided to have a go myself. Bought a repair kit from ebay for about £15, and set about it. There was some heat shrink tape in the kit supposed to tighten the repair when heat is applied. I found this to be useless and ended up wrapping tightly with electrical tape. I wrapped a small piece of carbon over the break,with a larger one on top and a final larger one again to finish. Left it for 48hrs and was pleasantly surprised at the result from a cosmetic viewpoint.. How it holds up long term is admittedly an unknown, but so far so good.

[Cowsham]

Just watched this, thought it should help the OP. 'ETOE' - Martin Grey, the German frame painter - repairing typical chainstay damage due to a dropped chain. Not quite the same damage but same principles. Sanded the area, applied resin, carbon fibre strips then perforated shrink tape which he then heated causing it to shrink, and that applied pressure same as a vacuum bag. Sanded smooth and ready to paint.

You'll also see earlier in the video he plugged derailleur cable holes with carbon rod as the owner wanted to just have Di2, filled them with carbon rod and inserted an inner tube inside the frame then inflated it to apply the pressure. The more relevant repair starts at 14:40.

I like the idea of using the inner tube to apply the pressure and my equivalent of shrink tape ( whatever that is ) , shrink wrap or shrink tubing for electrical work -- as long as it could be slid on from one end or at the break if it was bad enough.

[kylecycler]

I like the idea of using the inner tube to apply the pressure and my equivalent of shrink tape ( whatever that is ) , shrink wrap or shrink tubing for electrical work -- as long as it could be slid on from one end or at the break if it was bad enough.

I think the shrink tape is perforated, though, to let resin 'weep' through it. First time I saw the stuff, if only virtually, was in this Instructable on how to build yourself an entire carbon frame (not trying to give anyone ideas but good luck if you give it a go - I'm sure there are a lot of folk on here (including me) whose dream it is to build a frame, one way or another, out of any material, albeit most likely steel or maybe even bamboo).

https://www.instructables.com/How-I-bui ... and-a-bam/



You'll see that Instructable also details how to build a bamboo frame using carbon fibre wrap to join the tubes although I think there's some kind of snag with that in the long run - something to do with shrinkage - and it's actually more efficient to wrap the joints on a bamboo frame with hemp and resin - Craig Calfee wasn't just a pioneer with carbon frames, he was the same with bamboo and I believe he found the latter method to be preferable.

[Cowsham]

I like the idea of using the inner tube to apply the pressure and my equivalent of shrink tape ( whatever that is ) , shrink wrap or shrink tubing for electrical work -- as long as it could be slid on from one end or at the break if it was bad enough.

I think the shrink tape is perforated, though, to let resin 'weep' through it. First time I saw the stuff, if only virtually, was in this Instructable on how to build yourself an entire carbon frame (not trying to give anyone ideas but good luck if you give it a go - I'm sure there are a lot of folk on here (including me) whose dream it is to build a frame, one way or another, out of any material, albeit most likely steel or maybe even bamboo).

https://www.instructables.com/How-I-bui ... and-a-bam/



You'll see that Instructable also details how to build a bamboo frame using carbon fibre wrap to join the tubes although I think there's some kind of snag with that in the long run - something to do with shrinkage - and it's actually more efficient to wrap the joints on a bamboo frame with hemp and resin - Craig Calfee wasn't just a pioneer with carbon frames, he was the same with bamboo and I believe he found the latter method to be preferable.

That's quir stuff boy -- I wonder is it easy to get unwrapped after or do you take it off between the resin gelling and hardening like I do with plastic bags on fibre glass.

[Orbearacer]

small update,I glued two patches now two days to cure

[DevonDamo]

small update,I glued two patches now two days to cure

That looks a lot neater than my effort! Are you planning to add more layers of carbon? If so, I find the most time-efficient way of doing this is to add them as soon as the epoxy has become dry/tacky to the touch - typically 8 hours, or less if it's a particularly hot day or you're using fast-curing stuff. It's perfectly fine to do it at this stage (the only thing you need to avoid is messing around with it when the previous layer is so soft that you could accidentally move or distort it) and it also means you can put it on before 'amine blush' develops. (This is a waxy residue which often appears on the surface of cured epoxy, which you need to wash off with hot soapy water before applying any more or it will mess up the adhesion.)

(Edit: but I've never used that sheet which expels excess epoxy, so if that's what's requiring you to wait 2 days, then ignore me.)