Cracked Aluminium Frame - Carbon Repair!
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- Опубліковано 3 жов 2024
- This is a bit of an unusual repair for us, but follow the process on how to repair a cracked aluminium frame without welding using carbon composite.
This is ideal when replacement isn't possible or other repair methods aren't available in time.
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“For mental health reasons...” Now it all makes sense. 😎 Brilliant job, Raoul!
This man is gem
what makes sense? Ellaborate on that.
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!
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??????
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 👍
I wonder if I could fix a downtube crack just under the seat on my old aluminium frame bicycle?
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.
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.
I feel like Avanti forgot the golden rule of triangulation here.
Absolutely, it was a matter of when not if it would fail.
@@LuescherTeknik I'm not an engineer but after years as a bike mechanic I do wonder why I couldn't be.
You're not wrong. It's noting like structurally optimal with the top tube landing in the middle of the seat tube and the gratuitous bends in the chain stays.
I loved this video! BTW, that frame looks like its seen service in a war zone.
It gets used alright!
Cool, great to see.
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.
Interesting I didn't know that could be done, so there is hope for Alloy bike riders.
Darin Steele - unless I’m mistaken, Shimano sells an aluminum rim with carbon fairing (dish). I think Shimano stays away from 100% carbon rims.
@@robertp7209I think they dont do full carbon clincher rims because of this failure explained by this vid. ua-cam.com/video/7O95Cd-aogk/v-deo.html
BMX carbon forks (for racing) used to be a carbon/aluminium composite, where the carbon was just a fancy laminate.
Eric Ng - smart company. Besides, aluminum is a proper heat sink for braking, carbon is the worst material for it in every way possible.
@@robertp7209 Shimano do full carbon rims in their disc versions
Great video! An excellent piece of craftsmanship - thanks for sharing 👍👍👍👍👍
Very nice. Good to know that is a possible fix for aluminum frames.
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)?
fantastic job and a education too well done
Impressive work, thanks for sharing.
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.
So it would have been cheaper to buy a new frame? Awesome work by the way!! 10-10-10
Great work! 👍
A cool repair for a cool bike!
informative. carbon is everywhere in the bike industry, but barely understood by the consumer.
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.
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.
You're A Wizard Ping!
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...
Good work there.
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.
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!
I'm just going to guess at this and could be completely wrong. My thought is that the load and torque carried by the right hand chain stay is substantially greater than what the left side chain stay would see so there's no real need. Also given that the repair needed to be done in a timely manner as well as associated costs the broken chain stay was the only one worked on. Just a guess though.
That's a great repair!
No galvanic corrosion by placing the carbon directly in contact with aluminum?
There is a glass barrier ply to provide insulation.
@@LuescherTeknik smart! Just like what they do with aluminum honeycomb panels. Sorry I missed that part in the video.
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)...
Thanks, I mentioned the prep in the video, upto 7 plies depending on a few factors, the vacuum is to compress the material for better fibre load transfer, the strength comes from the fiber not the resin so much.
@@LuescherTeknik Thanks so much for sharing your knowledge. I'm also interested to know what etchant you used for the aluminium prep, can you suggest something I can obtain easily in Australia?
@@noeyedeer8732 I did some homework and the etching is acid. Since dealing with phosphoric acid solution is not exactly friendly for home-based work, I was thinking of vinegar, but am not sure the 2.5 pH of vinegar is low enough. I would be happy to get some comments on that...
@@LuescherTeknik Thanks for the input. Yes, based on the 1.5mm thickness aluminum used on 7000 series, it seems that 6 to 8 plies of 200gram/sq.m twill which should result in (1.5 to 2mm) should work.
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.
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.
There was a glass barrier ply to prevent galvanic corrosion, due to the stiffness of the dropout area the dynamic loads are limited if at all. I am familiar with Redux 420AB, I consider the viscosity to be a little high for wet laminating however use it as an adhesive.
SSShhhh you will put me out of my Aluminium tig welding job.
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?
Experience, the original aluminium design was less than ideal.
Luescher Teknik Yes it looks like that extended u-shape creates a lot of torque and shear.
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!
You never know. Maybe one of the riders has a disability and it is their only mode of transport.
azmanntoz yeah very true. Gets you thinking outside the box 👍
Let us know if Dad thinks this was weldable and how reliable the weld would have been.
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
Any specific names for the resin and carbon fiber used would be great. Ide like to replicate the strength seen in your repair as the rider of this bike is 6.4 220lbs
@@TGKProductions358 Did it work out for you? I’m contemplating doing the same repair.
Fantastic video and repair. What was the cost of this repair?
Great job, as we would expect no less! Did you also sandwich the left side preventively?
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
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?
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?
No, there wouldn't be any benefit, as the carbon is much stiffer than aluminium. Carbon would be taking all the load, while the aluminium would be flexing underneath it, basically doing nothing and just adding weight. Essentially you'd have a carbon frame with an aluminium deadweight on the inside.
When a frame snaps like that . It's a sure fact that the frame was flawed to begin with . How old is the frame ??
awesome! I was just about to do this on my mates Bianchi frame that crumpled on the downtube from an accident.
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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!
What should I use as an etching? Will alodine work?
Best is AC-130-2 but Alodine will be fine for this.
@@LuescherTeknik thank you for the reply! I plan on doing this exact repair next week! Fantastic reference video 👍🏻
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.
It was bonded prior to wrapping.
How many layers did you used on this ?
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.
He mentioned the reason for not welding toward the beginning of the video. He didn't weld it up due to the heat treat schedule the frame may require once welded.
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
We have repaired this type of thing in the past without issue, it is a case by case thing however, so would have to see it here.
@@LuescherTeknik Thanks for your response. Let's see if this works. photos.app.goo.gl/m9tar9hPRo4wDpB86 and photos.app.goo.gl/hnYtcjPjqkfKKWed7
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?
Steel is less reactive, but a barrier layer is recommended.
@@LuescherTeknik Thanks! I'm making a frame with CF tubes glued into steel "lugs" with MMA glue. I'm going to try a strength test.
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?
Maybe, it depends on the damage and the shoe material. I would need to assess it.
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.
Anzac or FFG?
FFG, It was HMAS Sydney, I just looked it up and it was decommissioned in 2015 so no longer operational.
Luescher Teknik thanks. I knew about the cracking with the aluminium superstructure on FFGs, but also knew FFGs were decommissioned when AWD came into service. And the Anzacs have some aluminium structure too and are on their 3rd masts (2nd upgrade) which. I also have a old work colleague who use CF cloth to repair his light weight alloy frame.
does anybody remember exo-grid bike frames....
1.5 speed
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.
With modern designs I feel like the designers rely on CAD software, with neither software nor designer having any understanding of metal fatigue or stress risers. The designs are often apalling, especially with alloy MTBs, which are designed to look very technical (with no actual technical merit). Kinda like the "technical" cachet of CNC-machined components, which many people consider superior, where actually they're mechanically inferior to other production methods like cold forging. I often look at bikes and think, uh-oh, there's a stress riser, and there's another, that looks underdimensioned for the load and so on... I actually predicted the fatigue cracking on my Felt MTB, which had a very obvious stress riser on the chainstay (brake caliper mounting plate). The level of engineering quality in the bike industry, with notable exceptions like Shimano, is generally appalling.
You can have welding specs but the person welding it can always make a little mistake on the day which leads to a fatigue failure down the road. These things happen.
@@benc8386 in this case the welding does not come into it, as there is no weld near enough to matter. It is simply a bad design. It cracked exactly in front of the (stiff) dropout plate, and on the transition from full cross-section to a C-cross section. Those are areas with stress concentration, due to bad engineering. You always need to "feather out" stiffer areas, otherwise this kind of thing is bound to happen. But the new production methods and CAD meant that experience was thrown overboard, and the things that used to be normal are now nowhere to be found. Have you ever wondered why the lugs on a steel bike frame never end straight, but always have scallopped edges that taper to a point? Exactly.
In case of my MTB frame, there was no error in welding either. The brake caliper mounting plate stiffened a part of the chainstay it was welded to (and the pivot point for suspension rods/chainstays was too high and behind the wheel axle, creating a bending force. The chainstay cracked several millimetres away from the weld. Clearly a stress riser. Felt tacitly admitted that they screwed up, because the replacement part they send me had a line of weld extended about 1.5 centimetres beyond the mounting plate, to feather out the load. That one did not break (yet).
Ben C - quality control. A welders performance can be periodically evaluated fully with destructive testing, as in a random audit, and all the time with other forms of evaluation. All depends on what is being welded and type of welding. Some welding is done by machine, one reason is to remove human factor.
@@horrovac That could have been a failure in the heat affected zone from the weld. But either way I agree it's basically a design fault. Unless it was Al I suppose and they didn't redo the heat treatment after welding on the caliper tab.
Put "carbon repair" in the video title :)
Thanks for the suggestion, done!