It's also probably worthwhile checking your front derailleur adjustment. We could suggest which adjustments on the derailleur might help, but it's typically less frustrating to just start from the beginning by removing the front derailleur cable, setting the derailleur position (both position on the seat tube, as well as limit screws), then reattching the cable correctly. If you feel mechanically inclined, the Park tool website also has good instructions for doing that. If you don't feel mechanically inclined, the shop you bought the bike from will likely check it out for free.
hi, thanks for the reply's, i just found out something, when i bought my shimano xtr crankset, i install the spacer the wrong way, Two on the left side one in the right side. while i was checking the intallation sheet, its show two on the right right (where the charing are) and one on the left side.. now is the right way..