While salts are the most commonly cited threat, several acidic compounds found on modern roads can directly damage a bike’s frame, paint, and exposed metal.

Atmospheric and "Acid Rain" Derivatives Sulfuric Acid (\(H_{2}SO_{4}\)): Produced when sulfur dioxide from vehicle exhaust reacts with moisture in the air. It is highly corrosive to metals and can lead to pitting on unprotected aluminum or steel parts. 

Nitric Acid (\(HNO_{3}\)): Formed from nitrogen oxides (NOx) emitted by combustion engines. Nitric acid can attack the finish and protective resins of a bike; while carbon fiber itself is relatively resistant, prolonged exposure to high concentrations can eventually damage the surface resin matrix. 

Organic Acids from Vehicle Wear Benzoic and Oleic Acids: These are organic acids found in brake lining dust and tire wear. When mixed with road spray, they form an acidic sludge that can sit in crevices, such as around the bottom bracket or headset, slowly eating away at protective coatings.

Alkanoic and Fatty Acids: Also derived from tire and brake wear, these contribute to the overall acidic nature of "road gunk," which can stain paint and accelerate the oxidation of exposed aluminum.

Anthropogenic Secondary Acids Carbonic Acid (\(H_{2}CO_{3}\)): Though a weak acid, it is formed when \(CO_{2}\) (a primary exhaust product) dissolves in road puddles. It contributes to the general "acidification" of road runoff, which can slowly degrade anodized finishes on high-end components.

Cleaning Product Residue: Not naturally on the road, but often introduced by maintenance. Strong degreasers or acidic cleaners (like some rust removers) can be more harmful than road grime if not thoroughly rinsed, as they can cause hydrogen embrittlement in steel or "clouding" in carbon fiber clear coats.