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I am currently in the process of building a new road bike and I want to preserve the nice look of my new hydraulic Shimano Ultegra brake calipers. Normally I'd just coat the the area I want to preserve with a good ceramic coating and/or wax after polishing out any imperfections but since it is a part of the braking system I am unsure if that would impede braking performance or be outright dangerous. I already know that brake pads and rotors near any wax or coating are a no go so the current process I thought about would be:

  1. Remove the wheel.
  2. Remove Brake Pads.
  3. Clean Caliper.
  4. Polish out any imperfections.
  5. Coat with a ceramic coating and let it cure.
  6. (optional) put wax on top of the coating.
  7. Wait until everyhting is properly cured (24h or similar)
  8. Put everything back together.

Would that process be okay to do or would that degrade the braking performance/be dangerous?

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    Check that the ceramic coating is good with high temperatures (100°C or higher). I wouldn’t use the wax at all for that reason, lest it melts and gets on the friction interface.
    – MaplePanda
    Commented Nov 23, 2021 at 1:20
  • On the bottle it was written that it is fine to use on car brake blocks that are laquered or powder coated but there was no safe temperature given. Can I just assume that it is fine if I can use it on car brakes that road bike brakes will work as well or di they get hotter than car brakes?
    – Brezelmann
    Commented Nov 23, 2021 at 10:36
  • @Brezelmann Road brake calipers shouldn't get hotter than car brakes. Think about the amount of kinetic energy we have to dissipate compared to a car.
    – Weiwen Ng
    Commented Nov 23, 2021 at 15:36
  • @Weiwen Ng you are probably right. The only difference I could think of would be the size of the car parts, the wind speed (and that some brakes have special airflow channels to cool them) and the fact that a car has at least one more brake acting during a braking moment. So at least in theory you could have it run cooler even though the energy is higher. But since I am absolutely no expert I asked for clarification
    – Brezelmann
    Commented Nov 23, 2021 at 16:02

3 Answers 3

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The friction interface is between the brake pad and the rotor so as long as they remain uncontaminated you shouldn’t have a problem.

The only risk is to get your polishing goo on the inner surfaces which might affect the pistons, consider using tape to seal the pistons away.

You’ll want to use a bleed block to keep the pistons separated while working. You might have got one with the brakes or a chunk of well sized wood/plastic will work too.

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It sounds like you are talking about the brake caliper, i.e. the little housing (with a greenish grey finish if Ultegra) that houses the brake pads and pistons, not the disc rotor.

The housing is made of aluminum. Aluminum bike parts are anodized and clear coated. We typically conflate anodization with painting. Anodizing really uses electrical current to increase the thickness of the aluminum oxide layer on the surface. That layer is porous and it can hold dyes nicely, but that is a separate process from anodizing. In any case, the clear coat is UV resistant and adds protection for the paint.

I am not familiar with automotive ceramic coatings. (NB: an earlier version of this answer confused your question with the ceramic coatings typically applied to rims.) My understanding from watching a couple of YouTube videos is that they are high-end options for automobiles. My view is that this is unnecessary given the existing surface finishes. If the ceramic coating is liquid, there's a potential risk that you end up contaminating inside the pistons, which would be bad.

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  • The plan would be to use automotive ceramic coating and then automotive wax. The ceramic coating is liquid but it is applied really dry on a sponge and not directly. In terms of amount you'd probably use 1-3 drops per caliper.
    – Brezelmann
    Commented Nov 23, 2021 at 8:15
  • @Brezelmann Fair enough. If you must do this, I think the key is to keep any coatings to the exterior of the caliper. Again, I see this as unnecessary. Components don't typically take paint damage barring collision. The brake calipers are small targets that are out of the way, and it's going to be hard for this to happen. If they did take a scrape, it doesn't sound like a ceramic coat would prevent mechanical damage either. The finish doesn't tend to dull just from regular dirt and grime.
    – Weiwen Ng
    Commented Nov 23, 2021 at 15:34
  • Some part is to not have paint damage. The other part is the ease of clean up. It is way easier to clear brake dust from a car caliper that was prepared that way. If you've done a good job with applying the coating a alcohol wipe or a wet towel with a litlle car soap can be enough to remove the grime of 5k km on the road without any hussle. If you didn't do it it can take hours getting it spotless by hand...
    – Brezelmann
    Commented Nov 23, 2021 at 16:06
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Don't do any of this. Ceramic insulates and brake parts strive to conduct heat out to the air. As for wax, don't get it anywhere near a brake.

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    I am now thinking that the OP was asking about a similar process to automotive ceramic coatings. I'm not sure how thick those coatings are or what their thermal properties are, and I'm also not sure that they're worth the money and effort (remembering that all our fancy parts are anodized and clearcoated already). However, those coatings are (I believe after watching a couple YT vids) designed to protect paint. I'd be surprised if they impacted thermal management, especially considering that the OP isn't thinking of putting them on the rotors.
    – Weiwen Ng
    Commented Nov 23, 2021 at 1:30
  • @WeiwenNg Yeah, I doubt that a 100 micron coat of “ceramic” polymer junk is going to insulate that much. I do wonder now: since there’s probably better thermal emitters out there than anodized aluminum, I wonder if a special coating could actually increase the emissivity and improve heat radiation?
    – MaplePanda
    Commented Nov 23, 2021 at 1:41
  • The ceramic coating is really a small coating. Probably only 1-3 drops per caliper. On regards to thermal properties I am not sure since at least for my coating it is written that I could use it on an automotive brake caliper (with wheel and pads removed). The same goes for the wax.
    – Brezelmann
    Commented Nov 23, 2021 at 9:06
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    @MaplePanda black anodising can have pretty good emissivity, but the amount of heat you can radiate isn't that great - most of it goes into the air
    – Chris H
    Commented Nov 23, 2021 at 9:34

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