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I'm trying to determine the best coating or combination of coatings for bicycles that I'm refurbishing. Along with other elements of making these bikes weatherproof (full chaincases, fenders, water shedding, internal gears and brakes, maybe rod driven brake levers, etc.) I'm trying to determine how I can make frames and parts last outside in northern midwestern (USA) conditions for as long as possible. It must be able to handle:

  • Frequent freeze-thaw, sometimes multiple times per day
  • Temperatures as low as -50F, as high as 120F
  • Highly saline water slush and sand thrown up on roads
  • Rubbing on main tubes against bike parking racks
  • UV Protection

Some sources I've read state that powder coated parts tend to chip and instantly rust from flexes or small impacts. Others, such as Eastwood's own video show show that if properly applied, powder coating can handle impacts much better, although this does not speak to the resistance to UV, nor if the test shown included an acid bath or any other priming agents for the metals. Additionally, I do not know how strong a factor the quality of bonding may be from lower voltage powder coating guns that are available to non-professionals.

Historically, I know that bicycle frames would use baked on enamels, which have been phased out for painting processes which do not require as much industrial equipment to plate, bake, and wash parts. Could this be as good or better than baked on powder coats? As a motivated bicycle enthusiast, I'm willing to make or buy any single bike-sized piece of equipment to turn frames and parts into the most bulletproof version of themselves that they can be, so that maintenance and manufacturing turnover can be lessened.

So, with only durability and outdoor longevity in mind (not aesthetics, color-matching, price, or availability), what coating system is best for bicycles?

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    I'm not a powder coater but from my research, it seems like there's a fallacy out there of equating all powder coats as the same in terms of their durability and corrosion resistance. The different types of powder bases vary a lot in porosity. The way some bike PC'ers do it is use an epoxy powder coat primer base, which is durable and has extremely fine (waterproof) porosity, and then put the color layer on top of that, because a lot of the pretty aesthetic layers one might choose aren't enough by themselves. Commented Jun 23, 2022 at 15:58
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    (Whereas it's also possible to just choose whatever pretty color, which is likely going to be one of the poly- bases, and do that in one layer, which can have problems corrosion under the surface eventually - which isn't to say it's bad or wrong on all bikes since it's also a cheaper process that might be good enough in some applications). I'm not making this an answer because it's something I'm also still trying to figure out. Commented Jun 23, 2022 at 16:11
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    If you want the ultimate in pure utilitarian durability with everything else coming in way down the list of priorities, look up what the PC manufacturers call "Functional" powder coating. It's ugly and doesn't come in a lot of options, but it's the utility type of PC that has an epoxy base and comes in the sort of colors you'd want to put on a shipping container or warship-mounted artillery piece. Its whole mission in life is longevity under salty conditions. Commented Jun 23, 2022 at 16:17
  • Absolute genius. Never considered doing what was done by the big dogs in the next most corrosive environments. Always thought they used cheap paint to always keep the new recruits busy. Commented Jun 23, 2022 at 22:22
  • I would probably go to an auto parts place and buy some spray paint. Commented Jun 24, 2022 at 2:41

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The information below is based on what I've learned from third parties. It is not based on personal experience with the techniques.

Powder coats are regarded as more durable than traditional wet paint. Cerakote is a ceramic coating that may be more durable than powder coats, and it can be applied to metal in general. The color selection for Cerakote is probably more limited than powder coating. Cerakote may withstand incidental friction (e.g. rubbing up against a bike rack) better than powder coats or paint.

I believe that the clear coat will protect whatever underlying paint or coating from UV damage, but the clear coat itself is a polymer, and I would expect all polymers to eventually degrade from UV damage. I do not have any idea how long this will take. It should generally take a long time. It would obviously be preferable to lock your bike indoors and out of the sun, but this isn't always possible.

Bike parts are generally aluminum or some sort of plastic composite. If aluminum, they are anodized black and clear coated. Alternatively, polished or matte silver finishes in aluminum are possible. Generally, I don't think that it's worth powder coating components to increase durability. For the rear derailleur, the main thing to worry about is scrapes in a crash, and no finish will prevent that. The hubs are protected from impacts - if the hub took impact damage, then a lot of the rest of the bike also took such damage. For cranksets, you may get rub from the rider's feet, but this is very unlikely to compromise the structure and the usual anodization + clear coat is sufficient. Basically, it’s not necessary to powder coat the groupset or other components, although you obviously can if you want to. Remember that you’ll have to strip the clear coat if you want to re-coat the parts, probably with oven cleaner or similar.

It's worth mentioning that titanium and stainless steel frames are unreactive enough that they can be left unpainted. They are significantly more expensive than regular steel and aluminum, but some cyclists might consider these materials based on that property.

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  • Initially when I used the word "bulletproof" in regard to the results I wanted, I only used it as a metaphor. However, looking at Cerakote, it actually achieves that literal characteristic. This is likely going to be the coating I use, and seems to be closest to the original baked enamels of the past: youtu.be/JqLyk_wGhDU?t=36 Commented Jun 24, 2022 at 0:02

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