rattling? front of bike? check your valve ring/thing i don't know what it is called, but that little ring that you screw down around the valve. if it is loose the valve may rattle against the rim. you probably know this, but your chain is still going to make some noise even with a perfect chainline. i've never actually seen (heard) a bike that is completely silent (although they may be out there). flip your bike over and spin the cranks (don't cut off your finger). if the noise is gone then you can rule the drive train/rear wheel out.