is there a lightweight chain cover for a fixie like Raleigh roadsters use to have
You could put some cable ducting over it, like Dahon do.
nice idea ( I first saw it circa 1984) but according to the LBS who sold the first ones local to me, what I saw on several parked bikes in the very first winter wasn't unusual; after a short time the ducting just fills up with (salty) water and the chain rots at a truly ferocious pace. I have never seen chains so rusty that were still attached to a bike, in fact.
I can see the attraction for a folder though; you don't get chain grease on you or other things so badly. [...]
Those things are noisy though. So I had three problems with them on my folder:
- the noise;
- the extra quick rust on the chain;
- the mud that stuck to them that could not removed well, unless I separated the chain and cover for that;
Also, given that no bus will transport my folder unless it is covered completely, its main quality was not that useful in practice.