Something in your home has got on them. Dust / some kind of cleaning fluid / lubricant of some kind.
Few of these things can survive the temperature generated by a steep descent with brakes on full whack. Repeat this until they are smoking.
FWIW, Shimano brakes are shite, in that the pistons have a habit of fucking themselves and allowing small but ruinous amounts of fluid to escape. It could simply be both being fucked.
Something in your home has got on them. Dust / some kind of cleaning fluid / lubricant of some kind.
Few of these things can survive the temperature generated by a steep descent with brakes on full whack. Repeat this until they are smoking.
FWIW, Shimano brakes are shite, in that the pistons have a habit of fucking themselves and allowing small but ruinous amounts of fluid to escape. It could simply be both being fucked.