This Chinese carbon bike frame was damaged in shipping, and a crack inside the downtube makes it unsafe to ride. The company OG-Evkin have already agreed to replace the frame under warranty, but can I fix it myself?

I use cheaper carbon fibre bike parts all the time, and things have broken and snapped on me in the past, but I have never tried to repair them. However it seems a shame to throw this bike frame away. The crack is in a very critical area, and if ignored, could easily spread and cause a catastrophic failure, but I think it can be fixed.

I bought a carbon fibre repair kit on Ebay for £12, which includes the resin, hardener, and a large patch of woven carbon fibre, but the issue is getting the patch in the right place. The crack is inside the downtube, and not easily accessible. There is no direct access, and I can only reach the crack from either the bottom bracket, or the headset. In addition, I need to apply pressure behind the carbon repair patch while the resin cures to ensure a strong permanent bond.

So in this episode, my brother and I spend an afternoon trying to repair this cracked carbon bike frame, using a cheap repair kit, some plastic bags, and a mountain bike inner tube.

OG-Evkin Frame – Use code ‘Tracevelo’ for 10% off at checkout:
QONQI Road Carbon Fibre Frame Rim/Disc Brake

Timestamps:
00:00 – Start
00:34 – Diagnosing the problem
03:37 – Discussing the crack
04:50 – The initial plan
07:30 – Repair discussion
09:22 – Problems to overcome
12:15 – The plan
14:52 – 1st attempt
17:42 – 2nd attempt
19:48 – Repairing the repair
23:20 – Removing the repair apparatus
25:25 – Checking the repair
27:10 – 1 month later
29:26 – Potential issues with the repair
31:31 – Bonus clip – Replacement warranty frame

Intro roll:
Created by Dev Joshi – http://www.go2dev.co.uk

Instagram:
https://www.instagram.com/tracevelo/

Email:
tracevelouk@gmail.com

Please note:
I am not a professionally trained bike mechanic. There can be risks associated with using products that are unbranded, untested, or come from sources where the provenance is unknown. Please talk to a qualified bike mechanic if you are in any doubt.

In essence, be careful, do your research, and cycle safe!!!

47 Comments

  1. Well done, Luke and Charlie for a great video! Amazing patience, troubleshooting and problem-solving skills there. Also congratulations on the new frame – it looks real cool! 🥖🥖🥖

  2. De myth-ing epoxy black arts. Before monocoupe construction, carbon frames were pieced together just like this. I repaired my Gaint TCR Comp BB shell blow out and held up 10 years. It can be done, and preparation is the key. Excellent video as alway!

  3. "… repair will last the lifetime of the frame." Well, by definition, no? 😉 But great job, fantastic results. You put a lot of thought and effort into it and I think it paid off.

  4. Luke, excellent video as always. Question on the stem setup – is this a FSA acr /smr style headset that you are running with a standard bar and stem? I am thinking of swapping out my integrated bar stem for something more traditional and wondering if I can do it with a standard bar and stem. Cheers!

  5. I bought the exact same carbon repair kit from eBay as you! I used it to fix a small crack in the seat post collar of my winter bike, if the crack was anywhere else on the frame I would have just binned the whole thing. I fixed it about 2 years ago and it’s literally been fine. There’s a lot of paranoia around carbon fibre, it’s not as fragile as people make out and it can be repaired amateurishly providing the damage isn’t too bad or in a dangerous place. Common sense more than anything.

  6. Great job Luke! When I saw the initial video of you telling about the cracked frame my problem solving brain kicked in and basically came up with something similar. You could've used a TPU tube though! Then you wouldn't have had the faff with plastic bags! Even though you seem to have fixed the frame, personally I'd still not ride it. Hang it on the wall as a reminder but I don't think it's worth the risk! Great content, well done again 👍

  7. Good job, I'm doing exactly the same thing right now to fix small cracks on a chain stay road bike frame using almost everything on that method except I'm using a release tissue to avoid the resin to get attached to a ballon.

  8. That's extremely impressive! I really didn't think it was possible to do this with such a terrible access. That repair looks fine to me, I'd ride it. The techniques you used are very smart, you two are geniuses! 🥖🥖🥖

  9. I bought an endoscope from aliexpress on sale for around $4 and had no idea what I was going to use it for. However, it turned out to be a great thing for checking where what. 🙂
    That cut frame half (with some wheel and handlebars) would make a god sign for a bike shop / bike repair. 😀

  10. brilliant !
    you did an Ok job, saved a frame from the bin.
    sanding, prepping, pressing, was bagette 🥖🥖🥖

    Sorry, here it is in short:
    -Help epoxy gel migrate in the original crack while pressing (pressing it from outside, tap and vibrate )
    – double the carbon weave in the center, possibly angled diagonally.

    I Would not worry about propagation points, and the stress by sharp modulus change,
    it's not like you put a stiff iron vise in it, the variations in your 1 layer woven layup and the epoxy thickness acts as a dispersive random pattern.
    Last observation, next time try doubling the carbon fabric in the center of the patch, It's the strands that brings solidity.

  11. Hey Luke, for additional insurance, you may want to add a Kevlar patch or two on top of the carbon patch. In the unlikely event the downtube fails, the Kevlar will hold it together thereby reducing the chance of a crash. You can also purchase woven fabric that is a mix of carbon and Kevlar tow specifically designed to address this issue….

  12. Thanks for all the kind words everyone! It was a genuine privilege to be invited to help Luke out with one of his videos – he's an absolute pro and puts his all into every video. We both had a blast and I'm so glad we managed to pull it off in the end. Snatching victory from the jaws of defeat!
    You guys are always so supportive of what Luke does and I can tell you that it means the world to him to have such an awesome bunch of people cheering him on. You rock! 🙂
    🚴‍♂🔧🪛🥖🥖🥖🥖🥖🥖🥖🥖🥖🥖🥖

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