rsbob 

Rust is real.

Maelochs

yeah well ... if you run into stuff you will hurt your gear. I had a beautiful Chromoly MTB but I bent the frame in a hard crash .... and always what is "reasonable" varies with each person, but nobody really wanted to try to straighten a kinked down tube ...... I girl I used to date damaged the chaionstay on an AL Kalloy ... and it is even harder to get Al repaired .... because of the heat-treat. And as someone mentioned above, if you break a CF frame you Can patch it .... but maybe you shouldn't.

As it happens repairing CF is probably the easiest, since it is just a matter of mixing epoxy and wrapping layers of CF cloth (I have a CF repair kit on hand just in case,) but as with any repair ... get it wrong and maybe you won't know ... until you hit a bump on a 40 mph descent and you die when the frame collapses.

However ... that is an issue of Crashing ... not frame material.

wolfchild

Rust is real but it's also a highly exaggerated problem. Steel frames rusting out is a non-issue for most people and majority of steel frames will outlast their owners. I have never seen a steel frame that was rusted out so bad that it was not safe to ride. I have two steel framed bikes which are 16 years old and used on salt covered roads here in Canada during winter time both frames have been treated with rustproofing oil on the inside and I don't worry about them ever rusting out.

big john

Having broken 4 metal frames there was no warning whatsoever.

Eric F 

Yep. It can happen with metals, too. Someone posted on BF a few days ago about an aluminum handlebar that failed suddenly.

big john

Eric F 

Ya know what never rusts? Carbon fiber!

dedhed

I'm thinking a materials engineer from McLaren has a bit of experience with carbon fiber and polymers.

https://www.motor1.com/news/492625/m...-carbon-fiber/

cyccommute 

There are a whole lots ofexaggerated problems in bicycling. Everyone knows that steel never breaks (it does). Everyone knows that aluminum lasts about as long as yesterday’s fish left out in the sun. Everyone knows that titanium never breaks. Everyone knows that titanium lasts just slightly longer than aluminum. And, finally, everyone knows that carbon fiber (or any material that isn’t magical steel) will shatter into a thousand pieces that will all target your eyes if you so much as tap it.

I have an aluminum frame that is16 years old with 22,000 miles on it with a carbon fiber fork that was OEM that was only retired because I wanted a different color bike. It’s still in my garage and might see service again. I have a 12 year old Cannondale T800 with 10,000 miles of loaded touring on it that was also retired only because I wanted a different colored bike. My supposedly invulnerable steel framed Miyata Ridge Runner which was the first frame I broke, has roughly 3000 miles on it when it had broken the 4th time…first it broke at the steer tube on the fork, then it cracked on the chainstays at the bottom bracket brace, then it broke at a dropout when an axle broke, and finally, it broke above the repaired chainstays. My steel Specialized Rock Combo lasted 4 years and 3800 miles before it broke.

In fairness, I broke two aluminum frames. One was a Specialized Stumpjumper Pro with an M2 frame which is known to break. It lasted 5 years and twice as long as the steel frames. The other aluminum frame broke because I put a HellBent seatpost with massive set back on it. But it was repaired and was still in use several years later.

In my experience, steel is rather delicate. I’ve had other steel bikes that have lasted longer than the two that broke and didn’t break when they were replaced with upgrades. I’ve also had other aluminum bikes that have seen long service. No material, be it aluminum, steel, titanium, magnesium, or carbon fiber is going to asplode because it is used in a bicycle. The material isn’t really taxed all that much by the light duty that bicycles put the material to. As I said above, there is a whole lot of exaggerated problems in bicycling that are indeed exaggerated and not nearly the problem that some people make them out to be.

cyccommute 

I think you missed Professor Marrow’s point. All materials degrade. Steel oxidizes to iron oxide, aka to the layman as “rust”. Aluminum oxidizes to aluminum oxide which is could be called aluminum rust. Titanium can be oxidized to titanium dioxide. Carbon fiber, most specifically the matrix, can be degraded by UV. Each material has its strengths and weaknesses.

In the case of the epoxy in the matrix, the epoxy doesn’t necessarily fall apart or change state like metals do. The UV causes the matrix to further cross link and become more brittle and less flexible and, thus, more prone to cracks.

Eric F 

Did you miss my TED talk in post #15 of this thread? I invite you to review it.

I, admittedly, don’t know everything about carbon fiber composites as a material for bike frames and parts, but I’m still pretty confident in saying it will never rust.

As for UV degradation, the “paint” defense strategy seems pretty effective. There’s also the “keep the bike out of the elements when you’re not riding it” defense strategy. Oddly, all of my bikes - metal and plastic - get the same strategy.

Also, my previous comment was specific to the post I quoted.

cyccommute 

Again, you seemed to have missed what Professor Marrow had to say about paint, which is another polymer that isn’t impervious to UV radiation. Granted a polymer bike isn’t likely to fall apart if some sunshine falls on it. But steel won’t rust if a little bit of rain falls on it.

These are examples of the “exaggerated problems” seen in bicycle discussions all the time.

wheelreason

If only there was a coating that one could apply to bikes to change their color, I'm off to the patent office...

Eric F 

I missed what Marrow said because I didn't look. I'm still pretty sure that crabon fibur won't rust.

You may have missed that my response to wolfchild was intended as a light-hearted needling, not an in-depth dive into materials properties.

EDIT: I finally got a chance to watch the video. It seems that Morrow's short comments about paint were related to clear coat over raw CF, not pigmented paint.

wheelreason

Well, in that case, I'll just add that if you set a carbon fiber bike on fire, you will get some CO and CO2...

Eric F 

Thanks for the info. Because of this, I just cancelled my plans to torch all my CF bike frames.

Atlas Shrugged

I am amazed that these bizarre debates continue regarding things like Carbon bicycle frames and components, even though the same exaggerations are posted from all sides. Thousands of comments have been presented, yet it begins anew at the slightest hint of chum being tossed in the water like this thread.

I also rise to the bait as I enjoy and find humour in imparting sarcastic insights to the discussion. In the real world, the carbon debate has been settled with almost unanimous acceptance at the premium end of the sport in frame materials and components. This is for a reason, as it is superior in most use cases. Luddites be damned. I mean, debating UV resistance as a possible issue, get serious.

As with everything else, decisions lie on a continuum, including frame materials. I purchased a steel adventure bike for a particular use case: a 4,000-mile ride across South East Asia next year. Steel because it is better suited for this kind of application, and the market has also adjusted for this with lots of steel options and minimal carbon ones.

On a less serious note, good luck repairing your steel, titanium or aluminum bike at home, yet carbon piece of cake.

indyfabz

So far (7 years), so good. But should something happen, the builder's shop is 12 miles away.

Darth Lefty 

Most frame failures other than damage are due to design failures or build failures - or in my business we would call them escapes and nonconformances.

Salsa had a steel frame in the early-mid-2010's called the El Mariachi and it had a persistent problem with cracks at a really hard bend in the chain stays. This was not an unusual problem for that generation across the industry and newer hardtail frame designs from everyone since mid-2010's have a drive side yoke made of plate.

Their mid-late-2010's carbon suspension bikes have been developing cracks in the seat stay link.

Both of them are impossible to repair. The steel one because any repair would be weaker in the same high strain location that killed it originally and the suspension piece because it was right by a pivot and no way to make an overwrap that would not interfere with the suspension action

Full suspension bike buyers seem a lot more tolerant of cracks than roadies. Oops, it's used up, hooray time to get the newest one

GhostRider62

I've had various things made from steel, aluminum, Ti, and Mg crack or break on my bikes.

I've never had a carbon failure and my first carbon bike was in 1986.

Airline partially crushed a carbon seat stay on the way to France, I did the ride with a partially busted tube.

Aluminum rims are garbage compared to carbon

cyccommute 

”Rust” is just another name for degradation. Or, more technically, a change in state of a material. All of the materials discussed above can undergo changes in state that causes a change in properties. Those changes are usually for the worse. No, carbon fiber can’t form iron oxide. But the epoxy resin in the carbon fiber matrix can undergo changes that are just as devastating to the properties of the material as rust is to iron.

Pigment won’t make much difference. It doesn’t matter if the paint is red, black, yellow, or colorless*, it is the polymer that makes up the paint, not what was put in it, that provides the protection. And that polymer is just as susceptible to degradation with or without the pigment.


*”Colorless” is the proper term, not “clear”. Colorless is lacking in color. A substance can be clear…lacking in particles that cause light scattering…and colorless…lacking in color…or it could be brown and clear…i.e. lacking in particles that scatter light. Tea (without milk) is an example of a clear, colored solution. Water is an example of a clear and colorless liquid and milk is an example of a colorless but cloudy liquid.

cyccommute 

Continuing to be pedantic, probably not. Carbon fiber…the actual fiber…is formed at very, very, very high temperatures. Burning it is going to be difficult. That’s one of the problems with recycling it.

georges1

Repairing a Ti frame requires knowledge and experience. My money would go with Dave Levy at TiCycles would be the perfect guy to do it. He knows titanium inside and out. One of the early builders. Repairs is one of his specialties. Titanium so no paint to damage. He also probably knows several other approaches. https://www.ticycles.com/services-overview

Eric F 

This ^^^ was my only point, and I made it half-jokingly.

I have no doubt that you are probably correct on everything you're saying. However, I have zero interest in getting into a battle about the accuracy of words. My apologies for not meeting your standards.

Also...lighten up, Francis.

georges1

You have forgotten the Columbus XCR and Reynolds 931 and 921 stainless steels and before them the Reynolds 953 was dwarfing them in terms of tensile strenght exceeding 2000mpa . You can prevent rust in a classic steel by spraying rustol or antirust primer in the head tube seat tube as well as inside the bottom bracket. When a carbon frame breaks it is hardly repairable unless you know specialist but is very espensive , otherwise it becomes a disposable worthless product. Whereas with a steel, aluminium frame and titanium frame you can always have it rebrazed or rewelded.