i ve a ravi piaggio , which is 5 speed it has the max ratio as following
1st 40km/h
2nd 70 km/h
3rd 90 km/h
4th 100-110km/h
5th after that
but to achieve good economy in city i do the following
1st 20, 2nd 30km/h, 3rd 40km /h,4th 50km/h and 5th 60 km/h, same ratio shud be applied to 125 to achieve good average and long life engine , u dont have 5thg gear dor 125 so continue 4th from 50 to on wards