Is the carbon frame disposal problematic

Question

I heard from someone that carbon is difficult to dispose of. Does anyone know how to dispose of carbon frames?

Answer 1

In principle, metal frames can be recycled. You would probably send them to a metal recycler. They'd get melted down. If titanium, you'd want to find a specialty metal recycler.

Unlike metal, carbon is not a homogeneous material. Frames are composed of many plies (basically sheets) of woven carbon fiber, usually impregnated with resin. Most carbon construction is currently thermoset, as opposed to thermoplastic. Thermoset resins are designed to set once baked, whereas I believe thermoplastic resins could be melted - however, thermoplastic construction is probably a bit heavier than thermoset.

Note that the Bicycling.com article linked above says this about thermoplastic:

This means the material can be reused to make new and different parts—recycled—somewhat easily. Manufacturing scrap, a broken part, or a product at the end of its life can be chopped up to become short-fiber-reinforced thermoplastic; which can then used to make smaller compression molded parts like stems.

Short fiber means the carbon fibers are not in woven strands. They're chopped up. I think they can make plastic parts stronger, but they don't have the full strength of carbon fiber. Thus, even if you could deal with the resin from thermoset carbon, you're basically looking at downcycling, not really recycling. This is obviously better than the landfill. As an aside, Silca's tubeless sealant is made in partnership with a firm that downcycles thermoset carbon fiber - my recollection is that they basically burn the resin off, although the resin partly fuels the combustion, so less net energy is used. In any case, say you could magically extract the resin - you'd be left with raw plies of carbon fiber. Those would have to be manually processed before they could be used in new carbon construction. Also, the ply shapes from the original part aren't going to match what people want for a new part. Thus, you probably can never recycle carbon like you could a metal.

That said, consider that our individual actions are insufficient for sustainability. You voluntarily recycling your carbon parts will not, by itself, address the systematic issues. The major problem with plastic recycling is that the cost of new material is much less than the cost of recycled plastic. As long as that's true, there is no financial incentive to source recycled plastic - you will have companies do this voluntarily, but they'll be operating at a cost disadvantage. Society will not solve this through individual admonishments. Now, carbon pricing could provide an incentive for manufacturers and consumers to use less carbon-intensive materials - that is, carbon taxes (as in taxes on fossil fuels, not specifically carbon fiber parts) or cap and trade schemes. However, these schemes are extremely politically controversial. Where actually implemented, they often price carbon too low - by design, because of the political controversy. It will probably take society some time to accept meaningful carbon pricing schemes. In the meantime, if you use carbon parts, consider keeping them in service for as long as possible, or selling them to someone who would make better use of them. Remember that carbon damage is often repairable by skilled technicians.

Recycling is the last option. You should be able to find carbon recyclers if you search; for example, Silca's manufacturing partner says they will take broken carbon parts, although you'll have to mail them in, as with the companies making thermoplastic carbon parts. I don't mean that you should not recycle carbon, only that it is insufficient by itself.