“For mental health reasons...” Now it all makes sense. 😎 Brilliant job, Raoul!

Thanks for sharing a really cool repair. As a layperson watching it's obvious that this type of repair is a bread and butter job for you while the rest of us are saying "How's that freaking thing going to last it's done"! Thanks again for sharing.

Following simple principles to isolate variables, you were able to devise what seems a complicated repair in its end presentation. Get this man a VB and Vegemite Sangy!

Great work. Repaired Cannondale CADD12 chain stay with a carbon repair. Where an oversize tyre had been fitted and worn it away. Though mine was a budget fix with fishing rod repair kit. But followed guidance on isolation and preparation. Over 10,000 miles of training later it's still going strong. Though certainly not as pretty 👍

Raoul, great video! I'd love it if you could continue this kind of 'how its done' theme where you discuss the processes you go through or necessary considerations for repairs or even just making things like your bike. I'm making custom shoes so its nice to hear the thoughts of someone who knows about cycling composites engineering, albeit for different applications.

This deserves a Platinum star award of excellence. Platinum is the second high award reserved for those who work tandems. Rhodium stars are those who service and repair recumbents. BTW thanks for the tutorial fascinating stuff and wonderful to see something repaired not just scrapped. Also why on earth would someone give this thumbs down??????

That tandem looks about as beat up as the one I saw a couple riding the munda biddi trail through the southern forests a few years back. High quality repair with an awesome description of the methodology, thanks mate.

Love it, I would have suspected that this could be done, amazing to see it. Great work Raoul, amazing.

Great video! An excellent piece of craftsmanship - thanks for sharing 👍👍👍👍👍

I feel like Avanti forgot the golden rule of triangulation here.

Impressive work, thanks for sharing.

Cool, great to see.

fantastic job and a education too well done

Very nice. Good to know that is a possible fix for aluminum frames.

Great work! 👍

A cool repair for a cool bike!

Good work there.

I loved this video! BTW, that frame looks like its seen service in a war zone.

One of your best Raoul. Wondering can you do similar for steel frames (specifically a Columbus Ultrafoco ‘Megatube’ downtube on a favourite old Paconi of mine which has cracked near where it is welded to the headtube bottom side)?

Super informative, I'm soon going to attempt this myself on my frame. I'm curious though if you sanded and grounded the final product into a taper or did you initially lay the layers in a stepped pattern so that there is a natural taper? My next question though is an issue that should at least be considered, maybe I'm wrong then someone could chime in. Carbon and aluminum (in my case 7005-T6) have a pretty substantial difference in CTE or thermal expansion coefficients. Where as carbon can even be negative (-1 *10^-6 in/in F) aluminum is much higher (13*10^-6 in/in F). Though bikes theoretically do not see drastic instantaneous temperature changes, they are used in a range of temperatures which for example sake can be close to a delta of 100 degrees Fahrenheit, though it is due impart to atmospheric conditions. This is of course dependent on where you ride, what time of year, do you store your bike in a car on a hot day etc. I see this as an issue for the bond because the aluminum will elongate at a larger rate than carbon when heated and I see this compromising the integrity. S-Glass fiberglass is stronger than normal E-glass and has properties closer to that of Aluminum, why not use this instead to repair the crack? Another property to consider as well is the percent elongation at failure but this comment is already pretty long so I'll stop here haha. Hopefully this is coherent and makes sense, let me know what you think, thanks.

Nice to see carbon fibre doing some environmental good for a change, stopping a frame hitting landfill or recycling. Also the owner now has extra bragging rights as his frame is a bonded carbon fibre and aluminium frame a bit like a Pinarello Neor which is mainly aluminium with carbon fibre stays.

Interesting I didn't know that could be done, so there is hope for Alloy bike riders.

Great job, as we would expect no less! Did you also sandwich the left side preventively?

I went through the first step of sanding down the paint around the cracked area on a Specialized Enduro chainstay and was thinking about doing something similar. Obtained a fiberglass repair kit by Bondo and thinking of using that, then layering up the carbon with another epoxy and hardener in-between days. Thoughts on that would be great.

Years ago I had a Specialized enduro 2nd hand where a rock strike or something had punched a hole clean through the downtube, an inch or so up from the BB shell, I had considered doing just what you did here, carbon over fibreglass. Instead I rode it for six months decided it was too much faff and sold the frame (highlighting the damage)... Wish I had done the composite repair now...

informative. carbon is everywhere in the bike industry, but barely understood by the consumer.

Fantastic. I'd be tempted to remove a lot of that aluminum for a more contiguous carbon layup. My instinct would also be tapering off the thickness of the carbon to avoid a stress riser at the beginning of the joint, which you did. Ah- foam fill. I see.

Great video and an even greater repair job. Very interesting to use carbon to repair Aluminium & as you said, it's nothing new. Poor design of frame where the welds are and a strengthen rib, just adds a stress point. There must be a fair amount of flex at the rear & most likely coming down the seat stays, acting on the rear dropout and that being the weaker area eventually breaks.

Raoul, could you perhaps give some details on the layup? How many plies, I assume that's UD with a weave cover, how wide the steps are and so on? Thanks in advance. Great job btw.

Needs a tandem for commuting and essential travel 😂. Having watched the video now - WOW this was really cool. I’m going to send this to my Dad who used to work as a welder in the aerospace industry. I bet he’ll find this interesting 🤔 I certainly never heard of composite repairs to metallic structures, be they bike, naval vessel or otherwise!

SSShhhh you will put me out of my Aluminium tig welding job.

Fantastic video and repair. What was the cost of this repair?

Awesome! I liked this a lot! It would have been super cool to see this in video format. I wonder if there would be any benefit to wrap an aluminium frame (or thinner tubes) in carbon fiber as a new manufacturing process, if cost was not an issue?

That was a really nice looking (as well as well-engineered) repair job. Do you get any galvanic corrosion type issues if you glue CF to steel?

i had a KHS XC207 Charinstay CRACK thats is how i purchased it , TIG WELDED still holding ip also had a Cannondale f29 Alloy Broken Seat Stay welded up and lots of Dents on the top and Down Tube Tig Welded Filled

You're A Wizard Ping!

So it would have been cheaper to buy a new frame? Awesome work by the way!! 10-10-10

Is there a good reason why they didn't have the other chainstay and dropout done while you're at it? I would have done it for piece of mind. Love the technical details!

Was the paint removed far enough? The edges of the fibre looks to be on the paint after repair. Or is that not an issue?

How many layers did you used on this ?

Did you do anything to the break itself, such as maybe epoxy bonding the joint prior to the fiberglass layer? I just wonder, if the two aluminum ends are just barely touching, some flex in the dropout could make it creak.

Carbon is stiffer and also sits on the outside. Outside usually see the highest loads. Repair looks fantastic. Did you match any properties of the Al frame with the plyes or did you rely on experience?

Im going to try this for a seat post that has snapped off from the seat being positioned too high on an electric bike. Thanks

Raoul. Great work. I have a Pinarello Prince 2001 with a cracked chainstay. I have aerospace experience (vaccuum bagging, 350F autoclaves)... I have some questions: 1) What do you use for etching the aluminum and as a primer 2) How many plies of a 200 grams carbon twill would you use? 3) Is vaccuum bagging really critical (it would seem that on such a relatively small area having a resin rich composite (and the extra weight) would not be so critical but of course porosity is much more of a problem)...

Interesting video as always! Are brake tracks on carbon rims repairable? I have a rim that structurally looks fine, no exposed fibres, cracking or damage, but there has been a chip taken out of the braking surface by a tyre lever. The main concern is over brake pulsing. Is there anything that can fill that void? It's quite shallow and flat. I'd imagine it may be hard to find a material that will offer similar braking characteristics. Thanks in advance

Is there a way to repair cycling shoes that have a carbon sole that has fractured? Is it possible to epoxy and layup some carbon on it for a patch fix?

That's a great repair! No galvanic corrosion by placing the carbon directly in contact with aluminum?

I respect your experience with these repair's but would S-glass be a better solution? No galvanic corrosion issues, S-glass very good with dynamic loads. As for Epoxy, Epibond 420 A & B is designed to bond to aluminum and glass, originally known as Redux. It too is designed for dynamic loads. It can wet out glass or carbon or be thickened with flocked cotton or mill fiber.

why not TIG the cracks before the CF repair? seems like welding would ensure the broken segments stay aligned and might provide a tiny bit of strength, in addition to the CF overwraps.

awesome! I was just about to do this on my mates Bianchi frame that crumpled on the downtube from an accident. . The video filled the last piece of the puzzle for me regarding the chemical etching and the primers! . was wondering if you used ferric chloride? and whats ur take on electroetching, would that also be suitable? :) cheers!

When a frame snaps like that . It's a sure fact that the frame was flawed to begin with . How old is the frame ??

There are no complications of heat treatment in bikes. Bikes are simple stuff. There is absolutely no heat treatment of bike frames other then overheating during welding. However if you have already that many cracks in some aluminum the best thing you can do is to throw it away.

Put "carbon repair" in the video title :)

Anzac or FFG?

1.5 speed

does anybody remember exo-grid bike frames....

I would think by now the mechanical engineers designing bikes would model them FEA. No high power computers of old days needed. If not, then stress test prototypes to failure including cyclic loading. The loading is clearly understood for bikes nothing new. An engineer would also be responsible for welding specs. The only (legal) defense they could offer is rider/gear weight overloading, or unacceptable road conditions. What a shame. Once again a potential serious rider safety issue.