Use the inner chainring and go to a 14 or 15 on the back and you will be about right. On three of my SSs I have similar gears with a 40 to a 15 (Trek 460), 48 to 18 ( Schwinn Madison) and a 44 to a 16 (Van Dussel frame). The first two are exactly the same and all are about 70 gear inches. Roger