FYI: 18/42 = 2.33:1 final drive ratio; 18/43 = 2.39:1; 19/42 = 2.21:1; 18/41 = 2.28:1; 19/43 = 2.26:1
If you want to get inbetween the 18 and 19 front sprocket (42 rear) and keep the 18 up front you would have to go DOWN one tooth on the rear to a 41. OR, you can put the 19 on front with a 43 rear which would be about the same.
