Every time I ride in the rain, next day I notice a brownish /red stain about the chain. Is not oxidation red/brown. Is that really rust. Appears so. I am very fussy about my bikes; plus, I tend to really get motivated when the sun is out. Whatever that red/brown stuff is, it looks like rust. It wipes off easily. I wonder what might be going on inside of the bottom bracket, etc should I think i see rust on a chain.