Are you a passionate track and fixed gear rider? Then for sure you would have had the feeling more than once that your gear ratio is to short and you could add a few more teeth. It is possible to replace the single sprocket with a different set of teeth, more adapted to what you are after. Even the road cyclist and mountain bikers can customize their "Miche" cassette which are compatible with "Shimano" and "Campagnolo" building them with a wide range of loose gears to suit you needs, from climbers to sprinters.