Sizing Chart These are the points our fenders are measured with a small margin of error. Seat size 14″ & 14 1/2″ will have 15″ Fenders Seat size 15″ -15 1/2″ will have 16″ fenders Seat size 16″-16 1/2″- will have 17″ fenders Seat size 17″ will have 18″ fenders. SKIRT SIZES Size 14 thru 15 will have a 25-26 inch skirt Sizes 15 1/2 thru 17 will have a 26 1/2 – 27 inch skirt Sizes 18 will have a 28 inch skirt generally.—–Our Gullets are measured between these points.