I just recently purchased the allez elite triple from a private party. Third time taking it out today and the bolt the keeps the crank arms on keeps backing out. The cranks are FSA cranks, not sure if those are what came with the bike. my question is this my lady friend just bought me a 105 crankset. the 105 is a double the fsa's are a triple crank set. can i just instal the new cranks without changing out the whole drive train? this is my first road bike so can someone clue me in TIA?