The last two really wet rides I’ve done, my back brake has seized on. Kind of pumped up until the brake is on full and I can’t pull the lever.

Taking the wheel out and pushing the bads back works for a while but then it happens again.

I cleaned the pistons and lightly lubed them after the first time, so sure its not that (only a couple of weeks ago) so what would be causing this? Happened on flat muddy crappy trails, so not caused by dragging brake on descents.

heres the solution

or

Has there been any other rides between them (ie, is it “the last 2 rides, which were wet” or is it “The last 2 wet rides but not the 10 dry rides inbetween”.

Kimbers, got both of them on other bikes, but actually quite like the Avids!

Northwind – probably half a dozen rides in between with no problems. Torrential rain seems to be the only linking factor as all my rides are in deep mud.

Ah well then I haven’t got the slightest idea. Sorry!

Avid = DOT fluid?

Fluid contaminated I’d bet. So I’d be checking seals for tears and leaks and looking to bleed them