A really good covering letter will get you in most bike shops, write about your experiences, how much you like bikes then big yourself up, that along with a clear honest CV will be fine, Everyone starts somewhere usually they will state if they need an "experienced" mechanic.
Hand it in person to the Manager/Owner and say how much you want the job and already know the shop well.
I've advertised jobs for shops i've worked in and you'd be surprised how many CV's turned up with no covering letters (mainly all A grade school qualifactions). They go in the bin after getting a letter from me saying "no sorry".