I have a set of Deore Hydros on my Cove Handjob, the ones where the master cylinder is parallel to the bars.

Last time I rode the bike (3 weeks ago) they were fine, stopping nicely, good power and pretty much as per usual as they have been for 3 years.

The bike hasn’t been washed since it’s last ride as it was in the snow and it’s been stored in my bike room, but today my brakes were squealing like a stuck pig and with no discernible power or stopping ability unless you properly yanked on the levers. Even then it was massively reduced and a touch scary at times.

Tried a quick trail side sanding of the pads and discs but to no avail. Pads are in good nick with plenty left on them.

Any ideas?

Not to the same extreme as you but my shimano brakes felt a bit crap after the crap weather so I cleaned and bled them and all seems well now.

Might give that a go, it’s the squealing that baffles me

When I rode in the snow my rotors got filled with a greasy slush that froze and made a right racket, could be that?

Ah another cunning suggestion, time to get the alcohol and blow torch out 😈