""I got a Cannondale Trail SL2 a few months ago""
did you buy it new or used? if you bought it new you should be taking it back to the shop. if it keeps loosening up there may be a an issue with it, there may even be an know issue (like in the auto industry where they put out Tech Service Bullitens) that needs to be addressed. if the bike is new you should not be turning wrenches on it
__________________
“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk