So i finally got a chance to ride my bike for a long time this morning...and thought it rode smooth, when i would shift gears it would take a while for it to switch (the rear gears) and when it finally did, sometimes it sounded kinda loud with the clicking. Granted it's been a while since I have ridden a bike, but I don't remember it being that loud.

Does this sound like just an adjustment thats off maybe due to the mcbike-assembler my target had put these together? I had read somewhere that this might be a common problem w/ new bikes, that it may be as simple as tightening a cable. This sound true?

btw its a schwinn trail way hybrid. 21 speed shimano shifters.