again.. do a search next time.

my example:

road 57 center to top, 55 road frame is the smallest i can ride.

track 56 center to top, center to center is 54 so that is the smallest size i can ride.

54 center to top is the smallest track frame i can ride.

the rule is get at least 1" of clearence between the top tube and the family jewels.

S/F<
CEYA!