Originally Posted by Sci-Fi

That's probably because the pads weren't broken in yet/correctly (assuming the pads were adjusted correctly) or the entry level Shimano M465 that comes with the Trek SU200. Takes about 10-20 hard stops before the pads are broken in. Pretty much the same break-in procedure as a car or motorcycle.

The Schwinn World DBX you are thinking about buying comes with the Avid BB-7, which is pretty much the best you can get in a mechanical setup without going to juicy's.