I heard that your bike should be running silently while riding if everything is working properly. Well today on my ride, I noticed especially on the three lowest gears while climbing, that it isn't silent. I can hear the rear cogs turning as the crank turns. There is no friction on the front derailer, and when I hopped off the bike and looked at the rear cogs, there didn't appear to be any friction with adjacent cogs (although it IS a 9 speed so maybe there is friction that I'm not aware of). The rear derailer limits are all set, and I was playing with the barrel adjuster for hours trying to make it run silently. I even asked some fellow riders what it might be, but they said it looked and sounded fine, but I could still hear the rotation of the cogs! What do you guys and gals think of this? I could also hear the cogs turning on some of the highest gears as well. Thanks for your help. The more info the better!