jayp410

OK, so you wrapped the whole BB and chainstay joint to create a shell. Were the chainstays still connected enough to provide the tensile strength? If the chainstays were actually broken/severed, I'd be very suspicious of riding that bike, with all of the tensile strength coming from a secondary bond between the carbon and steel. However if the steel was still connected and you just stiffened up the joint to prevent further flexing / metal fatigue, I could see how that would still be strong from a tensile strength standpoint via the steel.

When laying up successive layers of epoxy, it's best to do it all in one shot, to make use of the chemical bonds between layers. If done in multiple stages, letting the previous layer fully cure before adding the next, it's not bonding via chemical bond, and in that case it relies on a rough surface so that the new epoxy can "grip" the previous layer via mechanical bond, and such layers are more prone to delamination. Using rough sandpaper (or more easily, peel ply) can provide a fairly decent bond, but not as strong as chemical. Things can be embedded in between two layers (such as metal mounting plates), etc., before the epoxy cures, so you can still get the chemical bonding between layers of laminate, but the insert is mainly trapped / held in place by the laminate rather than bonded itself.

I think compared to boats, bicycles are much more critical and experience far higher loads. Boat hulls do slap down on the waves with sudden impact forces, but there's a lot of hull to provide strength, vs. a chainstay or seat stay on a bike which are very small.

As an aside... When I started doing fabrication with carbon fiber, the thing that surprised me most was seeing how flexible it is. A 1-layer sample of flat carbon fiber laminate (3K 2x2 twill, 5.7 oz/yd) is super flexible, like a piece of paper that can be curled up but springs back into shape. 2 layers is like a notebook divider, 3 layers is like a ketchup bottle, 4 layers is like a credit card, 5-6 layers more like a popsicle stick. People think it's stiff and brittle, but it's not...at least when thin and flat. Of course, when used in thicker thicknesses, and made into more rigid shapes such as bike frames, it does lose its flexibility somewhat, and we want it to. It gets its rigid strength from the shapes that are used. Sandwich materials are used (more in car parts...not so much in bike frames) where you can have honeycomb or foam in between layers of laminate and it multiplies the rigidity many fold.

I made 2 CF dashboards for my Miata... The first dashboard I made had 3 layers, and no sandwich material. It weighed 12 oz and could be pushed in by hand (like when waxing it), but returned to shape. The next one I made using 4 layers, with a honeycomb sandwich material in the middle. That version weighs 4 lbs and is very very rigid.

Also made a CF door for the Miata - 7 layers with foam core sandwich material, and weighs 7 lbs including a wooden brace where the hinge mounts to. (I wrapped the wooden brace with fiberglass and used a secondary (mechanical) bond to prevent the brace from delaminating. When clearcoating the door, I had it hanging from my garage door track, and it accidentally fell on its edge from a height of maybe 2-3 ft onto the concrete. The door made a loud "ping" sound when it hit, then BOUNCED back up in the air maybe 6 inches before I caught it! That barely left a scuff mark on the edge of the door. No damage was done.

Medium Size Dog

IMO as always. Not trying to claim any ethical high ground, just curious about the temperature of people responding to this thread. Google and Wiki reveal carbon fiber's toxicity and that so far very little has been or is going to be recycled or re-purposed. The environmental costs of steel and aluminum are well established along with the fact that they can be nearly endlessly recycled at a much lower cost financially and environmentally without repeating the damage of their original creation. All that damaged steel, aluminum and carbon shouldn't be tossed and should be recycled. I can only claim that my intentions are that when too old and infirm to ride my no chrome bikes, they will still most likely be in a condition where they can provide someone with many more years of dependable service.

79pmooney

The DS chainstay was cracked 2/3s around just behind the bridge. NDS 1/3, same location. I ran unidirectional along the chainstays from in fomt and over the BB to 4" behind the right crack and 3" behind the left crack. Then spiral wrapped more uni starting by circling both seat and downtube, over the BB shell then around the chainstays to the end of the lengthwise uni. Finally repeated that spiral wrap with strips of innertube very tightly to act like a vacuum bag and squeeze excess resin out.

The unidirectional had been given to me years before. I have no idea what it was, other than it was a weight appropriate for a primary hull laminate. End result - plenty of material, no voids, all done as a one-shot layup, plenty of bonding already beyond the crack and nothing loose that could start to delam. The original steel is now just there for the ride. (Oh, there's a solid mechanical bond to the BB with its bulbous shape. Also to the bridge which got a full wrap and the chainstay is tapered. It'd have to enlarge the epoxy/CF to pull out. That remaining chainstay steel is completely redundant.)

PeteHski

If you are going to have "ethical concerns" then I think you have to consider your whole lifestyle, not just what material your bicycle is made out of. There's a very high risk of most First World consumers being very hypocritical if they did try to claim a moral high ground in choosing a steel/alloy/titanium bicycle over carbon. Simply because of their other "bigger picture" lifestyle choices. For example is someone who owns several large gas-guzzling cars/trucks and a steel bicycle more ethical than someone else who owns a compact EV and a carbon bicycle? Or what about someone who owns 15 steel bicycles vs someone else with just 1 carbon bicycle?

Note: This is assuming carbon is even less ethical than steel on a whole product lifecycle basis, which may or may not be true.

Ghazmh

Cut off the joints until your left with a pile of tubes, top tube, chain stay, seatstay, down tube, etc. Use them in your garden to hold up your plants.

Milton Keynes

Hang it on your wall as a conversation piece.

Milton Keynes

But you have to list it as "like new" and ask a high price for it.

JoeO

I don't know what Cannondale's warranty is but I can't, in good conscience, try to make a warranty claim on this. There was nothing wrong with the frame The chain/gears got entangled and my body weight ripped off the whole thing. Even if this were a frame issue I can't see how I could show it. Anyway, I've already moved on to a new bike, I just want to close the chapter here.

rosefarts

When I was a teenager, most of the parts me and my friends broke got repurposed at least temporarily, yep, we smoked weed out of it.

Handlebar
A Canondale Killer V
Rock Shox pump

probably something else too but I uh, forgot.

I don’t think you can do that with a carbon frame.

rosefarts

Your fault, sure but they would probably give you a decent discount. That’s not “warranty” that’s just keeping you as a customer. Helmets and car seat manufacturers do the same.

JoeO

I've had both steel and aluminum bikes. I still prefer carbon. That's just me.

Never had a bike made out of plastic though; My parents never bought me a "Big Wheels" A tragic gap in my childhood.

jayp410

Let's talk perspective.

Consider the environmental impact of having a kid. All the clothes, appliances, electronics, vehicles, housing, and food they will consume, and the fuel and waste products associated. Also consider the possibility that they will have kids, making a potentially exponentially larger impact in the future.

I chose to not have kids, largely due to the above reasons. When I die, my negative impact on the environment ends. Also, I've been working from home the past 17 years.

So if anyone wants to have a conversation with me about the impacts of having a CF bike or working with carbon fabrication, you'd better have no kids when starting that conversation.

JoeO

I think maybe this thread has jumped the shark

scottfsmith

CF is being recycled, see for example This review. It discusses the state of the art for CF recycling. CF is getting used more in 3D printing filaments and recycled CF can work very well there.

The main problem today as I see it is CF production has grown very fast and the recycling channels have not caught up yet.

Re: fix or not, the modern repair places are offering lifetime warranties. A lot has been learned about CF in the last few years. I personally would be fine riding on a bike fixed by one of these shops.

unterhausen

One of the few constructive posts in this thread was copy pasta from a spammer who knows nothing about carbon recycling. The industry was making noise about carbon recycling a few years ago, but I really don't think they followed through. It's likely to be more prevalent in the future.

fishboat

Be careful with the terminology. Recycling (pure) carbon fiber is one thing.

Recycling a carbon fiber composite (carbon fiber "polluted" by, and enveloped in, a cured epoxy matrix) is a whole different kettle of fish. The article goes on to say: "While the technology to recycle carbon fiber composites has existed for several years and is capable of yielding a product with mechanical properties very near that of virgin material, the composites recycling industry is relatively young and is still in the early stages of developing markets for the materials it produces from recyclate."

Which continues to be the current state of the decades-old industry of recycling the plastics we already collect for..ah..recycling. One major problem with composites (mixed materials) is that they lack compatibility with other virgin or mixed materials. If the plastics aren't compatible(miscible) then their recycle utility quickly disappears. There could be a massive industry in plastics compatibilizers..if someone could come up with really good plastics compatibilizers(btdt). I read an article years ago about the P&G Marketing folks for TIDE clothes soap bottles were waving an environmental flag..had the statement on the label I think..about the bottle being made of "35% post-consumer waste"..or some such. The problem with that was by virtue of including the 35% post consumer waste they removed the bottle from the downstream pure polyethylene recycle industry and it went to a landfill..oops.

indyfabz

I think shark jumping is going premier at the 2024 Summer Olympics.

CliffordK

Many manufacturers offer a "Crash Replacement" policy (basically a small discount off of retail).

It is my belief that a replaceable derailleur hanger should be designed to fail in a manner that minimizes damage to the underlying frame. Not all damage can be prevented, but one shouldn't expect every derailleur into the spokes to take out a $1000+ frame.

So, yes, it may be a warranty issue. Or, at least it should be one.

cyccommute 

While I agree that a broken carbon frame is ready for the landfill or for use as an art object, it is not toxic. There are toxic materials used in its construction, that is true for every modern human made object on the planet (from the start of the industrial revolution on). But once cured, there is very little that is toxic about carbon materials. It is made of thermoset plastic which makes them nearly impossible to recycle. The resins used won’t “melt” and, when heated, crosslink further. That crosslinking makes them more resistant to being broken down by heat.

The fiber itself is calcined at extreme temperatures…up to 800°C (1470°F). That’s about 150°C higher than the melting point of aluminum. That makes the fiber very resistant to burning or degradation of any kind due to temperature. In other words, it’s hard to burn as is the resin. But that makes the material fairly stable to other kinds of degradation as well.

Mother Nature makes a similar type of material in every terrestrial plant on the planet. It’s called lignin and plants use it to hold together cellulose fibers to allow the plant to stand upright. It makes up about 20% of all plant biomass. There is no organism on the planet that utilizes lignin as a primary food source. There are some organisms that can use a small amount of lignin…along with cellulose…for energy but they are few. Mother Nature’s solution is to bury it deep and forget about it. We clever monkeys figured out that we could do other stuff with it and dug it up. We call it “coal”.

By the way, refining the materials for that aluminum can or boat anchor, requires vast amounts of nasty chemicals…far more than making carbon fiber.

Iride01 

If it's the drops that are toast and the CF repair place said it wasn't worth fixing, then toss it. CF should be perfectly safe in where ever they take your local trash. But you can check with your trash pickup service to be sure.

I'd have no problem cutting it up with a hand saw or reciprocating saw to make it fit in a can or trash bag.

Remember that fork is good still. Put it on the shelf or offer it for sale.

travbikeman

Thought your comment was interesting and decided to do a quick google search on this. I do find it interesting how much more destructive mining and processing aluminum is as compared to Carbon Fiber. But it is in some ways environmentally friendly due to it's recycle capabilities, but to get it out of ground and such is just wow!

I had read this article on comparing aluminum to carbon fiber and well it's really a toss up on which is better for environment:

https://www.pinkbike.com/news/alumin...ls-debate.html

In other words for all whom are interested, choose your poison or if really interested in having or supporting environmentally friendly transportation...walk!

cyccommute 

Yes, making aluminum for bauxite is very nasty. Reducing iron ore to iron also involves a whole lot of carbon from coal. Very nasty as well. We have a number of old coke ovens around Colorado which were use for making steel. The coke ovens were in banks of dozens to hundreds of them and they were kept burning 24 hours a day for years. Here’s the ones at Redstone. They operated from 1911 to the last 20s and then again in the 60s. They were hot enough to make the bricks into glass and to make the dirt between the ovens into brick.

rydabent

No way I would cut up a carbon frame!!!! Even with a mask you could get bits of carbon fiber in your lungs.

shelbyfv

But would it matter for someone already past their shelf life?

skidder

I'd just take a sledge hammer and smash it a few times at the center of the tubes to break it up so no one else tries to use it, then toss it into the rubbish bin. Always tough to loose a frame, but it happens (both of my losses were aluminum).

Pack up your sorrows
Trash man comes tomorrow
Leave it at the curb and it'll just go away
- Jackson Browne -