Bike Anti-Porn - When Things Go Wrong

Ah, I hadn't thought of the drainage in the lower field issue.

I can't think of a material that would be breathable enough, or a breathable design that would still enclose the chain well... which is a shame.

Something with loads of small holes wont protect the chain. But then none of my bikes have chain protectors and they still work. It would still keep oil and shite off your trousers though (providing you take it off to oil your chain and whipe off excess).

Definitely doable.