My front right brake has started making a sharp clunking/popping sound when initially applied from slow speeds. The pads have always had a lot of play and rattled in the calipers when rolling the bike around but braking has always been fine. Any thoughts? Also what is this about the Front Wheel Axle Spacing that I read about on the Maintenance Tips page? I recently put new tires on just put every thing back together the way it came apart.