My fe600 came with 15/42 gearing, i have a 16t countershaft sprocket but its tooo slow with the 42t on the back, i drive on the road a lot and just wanted the 43t/44t to go with th 16t counter, its not to actually go that fast but to be at a better rpm for fuel economy/engine longevity when at 55-65 mph, it is doable with 16-42 on the road, ok in the fields, but not good in the woods or rocks...just trying to get something a little better for both...