OK, I just got my bike back from the first, free, "checkup" the LBS gives. Fork was lubed, everything that needed lubing was, it felt overall better except... the brakes. When I brake they make this swooshing sound, not squeeking. I looked at them and I saw that on one side, the screw was unscrewed quite far (I realised because the screw was blue and when it was screwed in totally I didn't notice the blue).
I'm going to be riding some nice trails this afternoon with some mates and there's a quite steep downhill, where the brakes would get really annoying: Any ideas? Unscrew the screw on the other side aswell? Clean the pads?