alright, so i got my hands on a bianchi pista brand new for 550. no scratches, never been ridden, nothing. thing is i'm a 53cm... he only has a 55cm. is there a big impact if i get the 55? also my local bike shop told me that my inseam is 53cm and that my top tube is somewhere in the middle of 53 and 55.. i'm still growing (only 15). should i get it? or should i pass and get an iro mark v? if pass what other bikes would you recommend other than the iro mark v?