I currently have a Scott Aspect 20 2010 which I bought second hand. It was all checked and serviced.
After about a week of riding the brakes developed a rather loud squeaking, similar to the sound of a foghorn going off. I tried sanding the brake pads down, but that didn't work. I replaced the brake pads and for about a week the squeaking stopped (they were resin pads). I tried cleaning the rotors with an alcohol based solution, that didn't work. I have just bought replacement rotors but again that hasn't helped. Braking hard is okay, the squeaking starts when my speed is relatively slow, but is alright when breaking from speed.
Can anyone offer any suggestions? The only thing I haven't done is replace the fluid in the brakes themselves, but I doubt this would do anything.
My first suggestion would be resin pads, but it seems you did that. What manufacturer are they?
I went from metallic shimano to resin/organic shimano because of the terrible noises and poor
braking performance of the metallic pads. It quieted things down fine. I bought some koolstop
resins that are quite as well, but have a ton more grip, the trade off I am sure is way shorter pad life
but I will live with that.
Other than that are all your bolts tight (calipers, and rotors), loose bolts can cause unwanted vibration
in the calipers.
The pads I have I basically bought from Halfords, I think they're Clarke's. I've used them before on mechanical brakes and not had a problem. I've checked all the bolts too, and they're all tight. The only part that i'd say could be loose is the pads themselves. They go into where the pistons are and are secured in there by the spring and a split pin.
Reptile, you mention greasing the backing, do you mean the backs of the pads?
Remove the pads and heat each one with a propane torch for about 15 seconds. Lay them aside on something heatproof to cool. In the meanwhile, get some gloves on and clean your rotors with something along the lines of Finish Line Clean Streak or laquer thinner, using paper towels. Reinstall your pads and see if there's an improvement.
Okay I tried some grease and it's not really changed much, maybe the squeaking has gone slightly but it's still irritating
When I had my loud brakes, I put anti squeal compound on the backs of the pads (not grease, it's not made for the high temps brakes can reach),
I chamferd the edges of the pads with a dremel, I realigned the rotors, I tightened the bolts, cleaned the rotors with acetone, all to no effect. The resin pads cleared it all up, don't
understand why it didn't work for you? Maybe try another brand of pads?