I see online bike size for me with the horizontal top tube is 56cm. I do my inseam cm . Is 82cm x 0.69 is give me 56cm bike. say for bikes with the horizontal top tube. the for semi compact frames i do 82cm x 0.64 is give me 52.48 fdrame size. LBS tell me i need 54 cm. What is the correct size for semi compact.