Whenever I hear about carbon fiber safety I think of submarines for some random, undetermined reason. Maybe just me.

This video should be dedicated to all the Robs out there. The unspoken repairmen who fix all the things we dont know how to or dont have the tools to do so.

i hated the graph at the end with the 50 data points, unlabelled axes, and scaling "data"

Came for quality but the last 5 minutes of the video left me devastated Ryan please come back we need you

Did you just pan past a carbon fiber Honda XR650R without letting us have a better look? Come on fellas! Let us see that baby! Or better yet, devote an hour of your top-notch videography talking about it and reviewing it and racing it around and ultimately delivering it to me to ride around and then just kind of let me steal it and keep it and ride it forever and ever and ever...

The guy used different style weights, one spread the load out among 1ft of bar length on the repaired bars. The other put all the strain on a 1 inch section of the brand new bar with the metal weights clanking on the CF on every drop. C'mon. Completely different tests doing it like that. I've come to expect more from this channel, Fortnine is better than this.

Come on FortNine! You have been producing quality for so long, that I would hate for this new experiment to start a trend in the wrong direction. I loved the video, with the exception of the conclusion. Look, I get it that your weights broke, you may have changed bar type for the control, your sample number was low, your force measuring methodology is likely very flawed, but your conclusion was the worst part. The conclusion should be that the repair was not stronger than the other side of each handlebar in your test, and that the test rig and methodologies weren't good enough to conclude that the repairs were stronger than the new bar. You aren't known for being misleading, so I hope this sort of video gets more review before being released into the wild. Was Ryan out of town or something??

I love you guys, and I watch all your videos, but the testing had too many variables. The switch from sand weights to metal weights and the failure of the testing rig could have skewed the results.

I worked as the prep and finishing person at one of the longest active carbon fiber bicycle repair shops in the USA (I won't name them). 1. NOTHING short of a frame was every repaired for a customer. We experimented on bars and rims but it was not worth it. 2. we've never had a repaired frame fail at the repair point. They got to the point at the end but this was probably the least informed or informative FortNine video to date.

That felt like a stretch to justify a preconceived point. Rob's repairs we not stronger than the original parts, but they are stronger than some other completely unrelated parts... Ok then.

cutting carbon fibre using an angle grinder without wearing a mask is really not a good idea

Following this channel for a time now. I am more into the motorbikes, but carbon is everywhere, so still nice to know. However its kinda sad the quality of the testing didn't line up with FortNine usual quality. I mean, if you talk science, then really do it properly, even if you don't like the results. This it what gave this channel its twist. You got too many subs for returning to this "home enthusiast science" level.

but still, why didn't the other side break first? The additional bar you bought, was it the same make/model/year as the ones you destroyed before? Coz otherwise you can't scientifically compare the results

Cycles to failure is a very real concern for all kinds of equipment. At my old arboriculture gig, we would keep climbing ropes completely separate from rigging ropes, even if they were identical: we wouldn't trust a 6000 lbs test rope to support a man if it had ever been shock-loaded, or if it saw repeated use. Similar considerations were taken for all critical devices. Well done D.O.D.

Totally safe if done properly. Not unlike fixing fiberglass.

Been riding with a repaired chainstay for around 2.5 years now! I found a guy that usually does carbon fiber cars and he put a sort of carbon bandaid around 270 degrees of the chainstay. Its held up great since.

interesting topic, but I have to agree with the naysayers that the testing would have needed more consistency. In the end I expect your conclusion to be correct, repaired fiber plastic parts are at least safely usable. But the documentation and methodology was lacking and I am left unsure whether the conclusion is actually correct regarding low amplitude fatigue loads as experienced in most applications.

Making a semi-cameo here is Rob's killer vintage Bronco - that's its fender he's working on in the opening.

Mad respect for the Evil Dead 2 reference. groovy.

As someone who works with composites for a living there’s a reason why I have an aluminium ebike and not a carbon one(apart from the cost). I’m heavy and when I fails it just fails. As for repairing it, yes you can and you can make it stronger but you can just be moving the problem to around your repair as that will now be weaker than the repair. It’s just a minefield that can be easily avoided.

Let’s start a go fund me to bring back Ryan

I really loved the evil dead reference 😂😂

that episode has a good Mythbusters vibe. With less explosion. :D

Where is this channel going? Serious question

I learned about carbon fibre breaking last year

The surface of the load was different on repaired handlebars and new one. Repaired had weight distributed on more surface, around 10cm (more less width of grips) the new one had just narrow gym weight installed on like 2cm of the width of handlebar. Thats not apples to apples.

A thumbs up just for the Evil Dead/Army of Darkness reference.

I know someone else has said it, but the point still stands: The repaired end of the bars broke before the unrepaired and undamaged ends. The repair was not stronger than the original.

This seems to beg the question if Rob repaired a broken new stock bar, would it break at below or above the original strength? It'd be nice to assume that Rob can repair any carbon fiber handlebar to ~3500Nm break point, but given that his repairs were worse than the originals, it doesn't seem likely. It was nice of Rob to participate in the video but I think it's a stretch to conclude you should repair your new stock handlebar. Also, the dots are pretty but where are the axis labels?!

Due to the nature in which carbon fiber fails I've alway given it a wide berth, its alway catastrophic and almost never ends well. If I need to save a few grams I'll take a poop before the ride, if I need to save a load more, well, I'm 15kg the wrong side of a slice of cake or two, so I thing I'd be better off starting there!! An unplanned emergency dismount at 30kph with my bars in two bits is just not a good vibe!

The methodology is quite flawed, I'm sorry to say. The idea is great, but the sample size is too small and the difference in weights between the repaired handlebars and store-bought version, means the comparison doesn't really hold up. Same with the breakage of the store bought bars, as it could've broken because the rig failed, instead of visa versa. The big barbells are too wide, so the weight is distributed along a much larger area. The actual weights concentrate all their mass on a much smaller area, changing the characteristics of the shock load. Ideally, the weight is the width of a hand and is sitting on grips mounted on the bars. This test doesn't take into account variation in production methods and brands. As 1 of each was tested, you can have a bad apple and it is always going to break. To really have an informed opinion on this, you need to test multiples of each scenario, in a much stronger rig, simulating reality is closely as possible. It also need to take into account fatigue, load at odd angles and more. Carbon fibre parts are made in many different ways and have varying shapes, each with their own failure points. As the third broken handlebar showed, some breaks cannot be repaired. If handlebars (in essence a carbon fibre tube) can be fixed, it doesn't mean a solid carbon part can be as well. It might, but the results don't apply to all carbon fibre parts. I understand a test of this size is way beyond a channel like this, financially, but the conclusion from this video is based on a test that doesn't really prove anything. At best the conclusion is that carbon fibre can be repaired in some occasions and can be as strong, if not stronger afterwards. It all depends on the break and the part, and definitely requires an expert.

just seeing a shop with that much carbon dust around makes me uncomfortable... great that there are some individuals out there who are able to save those broken parts from being scrapped :)

I heard somewhere that particles from repairing (sawing/sanding) carbon fibre were pretty dangerous to the lungs. ? Nice video 👍

I repaired a Downtube headtube junction on a full suspension trail bike. Rode it a few more times and it broke again but on a chainstay pivot, so the whole “if the repair is better than the rest it will break somewhere else” has been true for me.

The graph at 10:30 has me scratching my head. what does the X and Y axis represent here? I feel like this XY plot should have been a bar graph

What I find silly is that those parts are essentially injection-molded plastic with carbon reinforcements. They're not "carbon fiber" in the sense that sheets of carbon weave have been laid together like you would find in a high-end bicycle or car frame; they're fiber-reinforced plastic like the more traditional glass-reinforced nylon. I find that confusing as the term "carbon fiber" gets thrown around a lot but now encompasses multiple manufacturing techniques, which produce wildly different results.

The weight of the narrow barbells is located further from the center of the handlebar than on the wide barbells. so, even though the weight is the same - the impact it produces on the handlebar - is completely different

Every time I see a band shirt during one of these videos, I think: this guy gets me, similar tastes in music and a love for two wheels! Happy belated St. Paddy's day, everyone!

Thank you for the Evil Dead reference

I've had a few carbon wheel rims come into my composite repair workshop. Buggered if I was going to repair them as instantaneous catastrophic failure, followed by a face plant, is a good way to lose friends.

BIG Thumbs up for the Type-O-Negative love. Life time fan of band and NY Hardcore in general.

Love the Type O Negative shirt. Interesting video too

Do I trust repaired carbon fiber? I don't even trust NEW carbon fiber! 😳 Steel is real, baby!

I was curious for you to break a bar in the test rig then have it repaired and tested again, would be better test I saw

R.I.P. Fortnine KZfaq.

To add to my doubt, you can´t test that simple how the repair holds up to stress, fatique and strain over time...

The comments about proper scientific methods have their place here, but may I be one to say thank you for trying to showcase the merits for repair! Carbon fiber is in our lives now and I love that Robert’s Composites is here in our front yard. If you broke something expensive, or it was part of something larger, repair should come to mind. Just because it isn’t perfect doesn’t mean it’s irrational. Customers of Rob will understand!

This has done nothing to convince me that carbon fiber is safe to repair. Your testing methods are flawed. Aluminum can be damaged and still be safe to use, while CF is a gamble. No thanks! I'm hard on equipment so ill trade a few grams of weight for reliability every day of the week.

What’s the explanation as to why it broke at the point of repair then?

Rob repaired a frame for us and it has been perfect ever since. We had him sign it and leave it unpainted just because Rob is awesome.

"Repaired carbon fiber can be as strong or stronger than a brand new product sold for the same purpose." -- While this concluding sentence is correct, I feel like it's shifting the goalposts a little bit. The repair is not as strong or stronger than the original. But it is stronger than another non-repaired but unrelated product.

Rocking the Type O Negative shirt, good one. Great video too!!

Well, you tell the fine repaired part is broken on 3500, but new on 2500. BUT on the repaired part was the second undamaged side that endured 3500. So, in fact, one bar survived on 3500, another is broken on 2500. It seems, that all is a crappy lottery.

I understand what you are saying but why did the ones that got repaired before break again and the otherside didn't

Where’s Ryan? This has been a motorcycle review channel for so long.

While the video editing was not as pretty as Ryan, I actually enjoyed this being a cyclist whom also rides a motorcycle. I got my carbon bike frame repaired professionally and always wondered about this. Im also curious about how much weight a carbon repair would add?

love seeing that Type O shirt!

I, for one, am digging the variety on the channel. And carbon fiber isn't just MTBs! It's good info.

Wow, there was no standardization in testing methodology between the commercial bar and the repaired ones. Y'all need to remake this with both a larger sample size (I'd personally like at least 3 of each) of each break type and repair job, as well as a consistent and repeatable testing apparatus throughout the entire test. Maybe also throw in a break caused by the test rig rather than artificial means, repairing it, then retesting it. I'm disappointed quite frankly.

Nice "Army of Darkness" reference. Definitely bonus points for that . . .

FortNine in America live from Detroit... Y'all had me with that first part.

And the funny thing is, I never got the movie reference until someone else pointed it out and called me an idiot ! Great stuff ! Thanks.

Love the Evil Dead reference!

If the repaired part broke at higher force... why in the first two tests pe handle bar broke ONLY on the repaired side?

Is this now a bicycle channel?

Music choice is great. Genuinely got emotional during the repair segment.

Can we get a link to the sick track that was playing in the middle and then again at the end? Love that funky groove, team F9! Also, I'm a pool player and I'm sticking with my woody. No carbon fiber shaft for me thanks. 😉

I'm a bit embarrassed by my fellow riders who are complaining about MTB content on Fortnine Now I don't pedal bike at all, but I still watch and enjoy these videos. I don't ride ADV either, but I still enjoy their videos when it's focused on that. It's a free content channel, that is affiliated with a beautiful Canadian company, that also sells MTB products. They also sell snowmobile gear, and I would not complain for a minute if their channel included some snowmobile content. If the topic of a single video is not to your liking, simply do not watch it, and wait for the next video that peaks your interest. There is no need for the disrespect.

im starting to wonder if there has been a movie reference in every video, and ive just been missing them until recently.

That intro summarized my worst nightmare in a few seconds clip.

Wouldn't adding that piece on the inside of one side change the balance? And what was the piece made or? Was it carbon fiber, or metal?

Type o negative shirt. Immediate respect.

Did someone just hacked F9 channel? 🤔

First of all - thank you for the video! Please read this one carefully. The breaking test itself is not good at all. The main difference in these type of composite material is the possible persistence of micro cracks during operation and their accumulation in time. It's really not obvious that if you would test a new element with the same maximum condition you did (without any other breaking tests) - it would always broke, the element could survive extreme condition at first. You did a few tests with lower weights before you use maximum weight. This can be the reason of accumulation of critical persistence of micro cracks that lead to the point where the construction is no longer good enough to resist the force you use. The same thing is with the repair! You can not be sure that your repair is goon enough till you check it at reasonable level. Ride safe! All the best!

Suprised by the Type O T, fking awesome

Wow! That was so cool, stylish and unique! Loved every aspect of that video! Love motorcycles, mtb and Vancouver, dudes! Thank you for your job. But help me with understanding, please. How is that happen, that last new bar was dropped from higher, but experienced less N of force? On first bar weights were kind of not centered right. We saw some Truvativ bar in some parts! Show us some proper branded parts maby? And the most important is - what results would a proper alloy Renthal have?

Still, I strongly dislike bicycle content. But this is Fortnine. You learn or you get entertained... in this case both.

What is supposed to be on the axis in the plot near the end of the video? I don't get what it's supposed to mean

Ive had both. Prefer metal due to bendy bendy than snappy snappy... Also whats the repair cost to new carbon bar ratio?

Great t shirt, great band.

This bicycle stuff needs to be on a side channel…

Love the windsurfers!

Pretty sure that buying new part would be way faster and cheaper than finding local Rob with repair bill more than cost of the new part.

Why are you doing bicycle stuff? Where's the snappy dude who does murder cycle stuff ?

Overload failure & crack propogation, as what happened to these bars, are not the same as fatigue. And with the retail bar covered in tape, it was also changed test configuration. Overall your point is true that sometimes carbon fiber parts can be repaired to be as at least as good as original--functionally. But per data, the repair changed the geometry by adding extra material & load distribution on the area of repair, so the strength is going to be different with the same force vs a new tube.

Always pleasing to the ear to hear a Canadian say "beauty" in his native environment.

3:40 watching the progression of carbon fiber, reminds me of Dave Ronneberg, and building the boot, after growing up with my father, that built a long easy and a cozy MK 4. N528DR and N785R I think those are the ones. He built a couple of “epoxy boxes”, to keep it warm… I still remember the smell

Have read some of the comments, and have a few thoughts. TLDR; It's an interesting video that isn't entirely wrong in it's point, but it feels like the type of experiment where you came up with a conclusion, and then set out to do some tests to just confirm that conclusion regardless of the actual outcome of the tests, which is a very bad way of testing something. Plus the explanation feels a bit like it's just glossing over everything except a small point that may not actually be relevant or accurate. For the readers; To the general conclusion, I agree that having some basic knowledge of your kit is good, even if you aren't going to work on it. Knowing you don't need blinker fluid is a good thing. To the specific conclusion, I think it depends on the type of break and the event that caused it. If you broke your bars like that by full speed clipping a rock wall, that's probably fixable. If your carbon frame took a tumble and cracked the head tube, maybe not. Definitely have someone who knows composites inspect it though. Carbon fiber is certainly repairable, but only sometimes, not particularly easily, and often at the cost of weight and bulk, which is the strength of CF in the first place. Hence the conclusion, "it's [probably] not worth repairing" To the methodology, there are definitely some issues with the process and sample size, but I also see some other issues. One big issue is the force measurement in the first place. The independent variable is the drop height, plus the mass of the weights if you had to change them after maxing out the height. Having the force is a useful data point, but it's not the factor being changed. Also, where is the accelerometer located? If it's in the center of the base or the bars, you would likely read a lower peak impulse at the breaking point due to the weights being detached from the bar before they have a chance to fully transfer their inertia into it and rebound back up. I'm a bit surprised that the first two bars didn't experience this, though possibly the height spacing was such that the peak force would have been between the two pegs? (This is based of my intuition with similar testing scenarios, please chime in if you have more experience with that type of setup) Additionally, with the extra set of bars you seem to be talking about them failing due to fatigue and at a lower force than the repaired bars and a lower force than their peak, but regardless, that only really shows that the third set was not as strong as the two originally were. (Plus maybe the impulse measurement issue above) I assume the point of the last test was supposed to be to see if the repaired bars failed at a higher force than the unrepaired bars would have failed at, but using a different bar makes that kind of meaningless. It also doesn't make much sense given that if the virgin side of the bar didn't break at that height, a full bar likely wouldn't have either. The weights were also different between the first two sets and the last one, which confounds the result even more. (Also as someone with way too many 3D printed things, a shim for a set of barbell/dumbbell was probably a better idea from the start) It also feels like the whole chart section doesn't make a lot of sense? What do the hollow circles represent? There were only a few tests shown, definitely not that many. Were those bounces? Were there more tests than were shown? Also, the peak vs break forces aren't labeled. Why is the second-to-last force measurement highlighted at all? Why are we just now learning that there was a "fancy" vs "quick and dirty" method? Which was which? What is the X axis? Also, why is there an X axis? Actually, why is this a scatter plot at all? This definitely feels very out of place for F9. Having the whole video be "you should do a thing and it will often be as strong or stronger" _does test and determines that thing is not as strong_ "as you can see, you should do the thing" just doesn't make any sense.

Ryan's let himself go 😂

How much to repair and how many carbon fiber repair places are near by?

Years ago I had a carbon road bike frame fixed by Robert's Composites. I rode and raced it for ages after and was confident it was stronger than new.

Loved the intro

I'm watching this days after breaking cheap chinese aluminium handlebar risers that i put on my enduro motorcycle.... yes. from now on i will be careful and learn about what i'm doing. D'oh! thanks for the videos guys, good job!

@FortNine do you mind sharing your 3D Printer Files vor the Test-weights ? I Love 3d-Printing and want to get "Fit for Riding"

I don't mind the bicycle stuff, or the new cast, but please, do the actual tests better. Switching weigth types and not using the same handlebar at the end. So his repair was stronger with a wide soft sand weight than an unknown knockoff was with a steel weight. That does not tell me much. Integrity is so important for this channel.

The biggest problem here? Carbon fiber handlebars almost never break towards the ends. They almost always break near the stem and it's really obvious that they're toast. This video is much more applicable to anything other than handlebars

This man the reason I don’t like KZfaq

Back in the day when I raced Rob Mulder’s boards were THE custom race board … note his T-shirt; Sailworks is Canuck transplant Bruce Peterson’s race sails, used by pro racers worldwide. As demonstrated, carbon can be repaired as strong (or stronger) than original. And I have had an aluminum stem fail “catastrophically “ without any signs or warning.. so carbon isn’t the only material that can fail in such a matter. Thanks for the content!👍

You needed to calculate the impact energy, impact force and impact torque. The gym weights would’ve acted like a point load so the torque on the repair would be greater as the second moment of inertia of the bigger masses you started with would’ve been imparting a simple sheer force through the repair and this is the strongest loading mode of a sleeve repair. You probably need to look at the amount of bar flex that is happening as well and compare the strength of the sleeve with the carbon fibre. Some sort of NDT (ultrasonics or dye pen) to look for signs of fatigue failure (cracking) should’ve been done between tests with this sort of testing method. If I were to do this, I would get a load cell and a chain block, clamped the bars onto the ground or something heavier than the breaking load, so based on the numbers you have in the chart about 800kg (4000N per side). I would then sling the bars with a load spreader to make it so you have vertical loads at the handle part of the bars. Could probably use grip to stop the slings from slipping … then you just read the load cell display as you wind on more load with the chain block until it fails. This way it’s one load event per test and it’s infinitely repeatable.

This was a really cool watch! Keep up the awesome work y'all!