Hehe, wellll, I think in this case patina means the loving and intimate thrashings of your most beloved steed. The one where you ripped the stickers clean off, gouged the chainstay, dented your top tube, dulled your paint. All this done while riding hard, that's patina. Battle wounds you can be proud of.
well i crsahed my bmx once and got a hole in my arm down to my elbow i.e torn skin which the nurse then inserted a needle cap to see how far down the hole went, down to my elbow was how far!