So I went to Wally wold today and they had the rare green and blue truster fixie. Bike in stock it also has nice caliper brake and strong l frame but there's one problem if I turn the bike upside down and pedel it the chain loosens and tightens slightly when its in free wheel it looks as if the bearing or whatever in the middle of the sproket is unbalnced its barely noticible but I'm just wondering if its safe to put a china girl on it or not I would return it but they are sold out of this color and the warehouse is also sold out of the color and on walmarts website so will it be okay to keep it? Thanks