My cassette (14-28) gives me all the gearing I need year round. When I'm not riding hard in winter, I use the (50 ring) 19-20-21. In summer when I'm in better shape, I am using the 15-17-18 a lot more. In winter I might need to go tot he small (34) ring, in summer I'm usually OK on a hill in the (50 ring) 28 cog.