I've used plastic bags to good effect before, in particular on the TCR when I don't have capacity to carry loads of gear.
They work very well between two layers of sock, and can keep the inner one dry while the outer one gets soaked during a downpour. Then magic happens if you keep riding and it warms up (but not in UK winter!): the wet sock gets dry and the dry one gets soaking wet, with sweat!
Putting the bags inside the sock is something I wish I'd done when I had this brainwave on LLEL a few years ago (spoiler: they let loads of water in and I got trench foot) : /
I've used plastic bags to good effect before, in particular on the TCR when I don't have capacity to carry loads of gear.
They work very well between two layers of sock, and can keep the inner one dry while the outer one gets soaked during a downpour. Then magic happens if you keep riding and it warms up (but not in UK winter!): the wet sock gets dry and the dry one gets soaking wet, with sweat!