Chain drive of two bicycles both double row, while there are 5 pinions for the bike up and 6 for the bike down. The gear ratio between the two bicycle uses a different philosophy, the bike at the top has a high variation between the sprockets, while the crowns do not vary significantly, in this configuration using the transmission primarily through the sprockets, while the crowns are intended primarily for the type of use of the bike such as plain, or climb very steep climb. The bicycle bottom uses of the pinions very similar between them and crowns very different, this configuration makes sure that you must use the change in the progressive and complete, initially with the crown small and the large sprocket, climb ratio with sprockets, once inserted the smallest sprocket to increase the ratio you have to go to the large chainring and the largest cog, this allows for many useful reports with few toothed gears, but makes use less practical.