I have a new bike, probably a month old, which has Hayes cx 5 disc brakes. I've noticed that the front brake pad is making a grinding sound when I brake at low to moderate speeds. What could be causing this? The pads that come with these brakes are Semi-Metallic.
The rotor bolts are all tight, there is no pad rub when coasting, and the bolts connecting the brake to the fork are tight.
Disc brakes sometimes need to "bed in," which means the pads will wear quickly at first then settle. During this period you can get some pretty awful sounding noises anywhere from screeching and squealing to grinding. BikeRadar has a great workshop article about how to go through this process.
Other than that, have you ridden through some wet areas and maybe picked up some dirt? Contaminants on the the rotors or pads will cause some extra noise as well. Sanding the pads can help remove any surface dirt/grime and improve braking ability as well.
Last option would be that there is something wrong with the pads or the pads are mismatched to the type/brand of brake. You could remove them and take a look and see if the wear pattern looks weird or if there's anything lodged in the pads themselves. It's pretty unlikely, but defective parts do happen.
Metallic pads tend to make really ugly sounds at lower speeds. If it is a rather high pitched grindy-squeaky sound that isn't particularly loud, there is no visible damage to the rotor, and there is no perceptible reverberation through the frame or brake lever that coincides with the sound then it is likely normal. With metallic pads, you literally have metal rubbing against metal and this can make some rather nasty sounds. From my experience the sound can be worse with a wavy rotor which is what most manufacturers use now. If you're not used to running this type of brake, it may be difficult to form a basis for what sounds normal vs what sounds like trouble, so if you still have doubts I recommend you pay a visit to your local bike shop.
I have disc brakes to and they screeched a lot when i first bought my bike. all you need to do is to ride your bike around and brake continuously. this will wear down your brake pads so that all the brake residue is on your rotors. this does take time so be patient. this is the exact process with rim brakes ( v brakes)
