I washed my bike few days ago with soapy water. I didn't directly wash the brakes, but I assume I got some soapy water on them.
Now my disc brakes do not work. I can see that cable is tight enough, and the pressure is there, but it does not stop.
The front brakes are better after 1 day of driving (but still are weaker than before). The rear breaks are pretty much useless.
Details about the bike & brakes:
Bike: Cyclocross (bought last year)
Brakeset: Tektro Lyra mechanical cable actuated disc brake with 160mm wave rotors and Shimano ST-2300 STI brake levers