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I recently did a big clean up of a bike that I bought and when I was washing the bike there were specs of dirt on the frame that I couldnt remove, I tried a soft brush, Muc off bike cleaner and (water obviously), but the dirt wouldnt go, but I have some motorcycle degreaser that I could spray leave and then have a got at wiping that off, but I was wondering if that would damage the paint and if so, what could I use? Thanks Charlie

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  • Thanks very much
    – Charlie
    Mar 30 at 19:09
  • I would be leery of using the degreaser on a carbon frame. And you should keep it off most plastic parts. Mar 30 at 20:58
  • @DanielRHicks are automotive degreasers that much harsher on paint than bike degreasers? Generally, our frames are clear coated, and that should resist exposure to degreaser. The sort of stuff that can eat through clear coat and resin is more rare, I think.
    – Weiwen Ng
    Mar 30 at 23:02
  • @WeiwenNg - So what is a "bike degreaser"? Mar 30 at 23:15
  • @DanielRHicks FWIW, The Trek/Bontrager bike wash, and degreaser, are the same formula just at a 10x concentration/dilution with water. I would be careful about extrapolating to other degreaser formulations, however, my understanding is that they settled on the bike wash first, and then found that the concentrated bike wash worked well as a degreaser. The only other cleaning solution I know of that Trek publicly approves to be perfectly fine for finishes is Dawn dish soap and water.
    – Pisco
    Mar 31 at 16:38
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You will want to look at the active ingredients of the degreaser to see if it contains any strong solvents. You will also want to consult your dealer or manual for the type of paint coating on your bike. The name degreaser is a bit of a misnomer; it contains an oil that dissolves oils within the medium which allows a majority of the dirt to slide away. However, degreasers leave a thin layer of oil no matter how much water you spray on it which is why you cannot paint over degreased surfaces.

Solvents only leave a film of solvent which eventually evaporates into the air, leaving a bare surface. However as they generally have high chemical energy, these are what can pull off finishes.

I would try low abrasive dry cleaners like baking soda or bleach powder (Comet) first as it will slightly abrade and maybe even polish your paint rather than risk dissolving it.

See Applied Science's video for details on different cleaner types application which is extremely useful in more than just cleaning vehicles.

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Try rubbing alcohol first if you want to be safe. Assuming that moto degreaser is good to use on painted moto parts, it’ll be fine on bike stuff too. Modern automotive-style paints are very resistant.

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  • On the Trek University video module “COVID-19 Update:Bike Wash Procedure,” alcohol in particular is said to have a deleterious effect on painted finishes. “There’s gonna be a big tendency to use cleaning solutions that are too harsh, and that will damage your customer’s finish. Things like ammonia, bleach, isopropyl alcohol- those will create damage to your customer’s finish.” My understanding is that alcohol over time Can damage the clear coat and cause the paint to get hazy.
    – Pisco
    Mar 31 at 17:21
  • @Pisco Powder coat is not affected by alcohol by nature. Enamel-style paint is possibly affected (my chemistry knowledge is lackluster), but I’ve never seen damage from its use. Usually you need stuff like paint thinner or stripper to effectively remove those paints, not just isopropyl alcohol. Sounds like a cash grab from trek in my opinion.
    – MaplePanda
    Mar 31 at 18:50
  • I think it’s more an issue of do no harm, considering the potentially wide variety of finishes one might encounter. Nobody said alcohol was an effective paint stripper, but if it just softens the clear coat that would be a reason to avoid it in a professional setting. I’m hesitant to call the unqualified endorsement of Dawn dish soap and water “a cash grab from Trek,” but when they couldn’t find anything else to recommend, it definitely suggests they didn’t test every other bike wash on the market.
    – Pisco
    Mar 31 at 19:46
  • @Pisco Powder coat is epoxy plastic, and automotive style paint is polyurethane. Neither are directly dissolvable in alcohol. Yea, I guess you can’t run the risk on a customer’s bike. Surely bontrager advertises their bike wash more than they do Dawn soap?
    – MaplePanda
    Mar 31 at 20:51

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