I've just been removing all the black goo that collects on the chain, cassette etc. over time & I was wondering what the black goo actually is and where does it come from? I realise it's partly water and grit spraying up from the road as you don't need to degrease stuff as much in the summer months, but how can water and grit turn into such horrible, black, greasy goo?
NB: If you are unsure what I'm talking about then you clearly clean you're bike far too often. I suggest riding it for a good few months without cleaning the bike at all and you should then have a good build-up of the goo to which I refer.