EURO-ASIA's grades of 17T are available! Of course, there is stock other than 17T! The reason why you press the 17t cog is that it is convenient for setting the gear ratio and the condition of the skid point is good. There are two tables, but one is a gear ratio, and one is a skid point table. The gear ratio is the number of how many rotations the rear wheels will rotate while the legs rotate in the crank, and the skid point is the number of places to rub when skid. In short, if the gear ratio is set to 3, the skid point will be 1. In addition, there is a combination that becomes a taboo skid point, but if you use a 17t cog, there is no problem if you avoid the 51t chain ring. By the way, today's Yokohama staff chain ring and cog sizes look like this. 47t x 17t = 2,76 skid points 17 (JUNKI) 49T x 16t = 3,06 skid points 16 (yourself) There are so many gear ratio among the staff. It's a part where you can get a lot of taste. In general, 2.88 of 49T x 17T of 49T x 17T is a classic. As a recommendation, the gold medal used by Mizu is used by the staff of the Yokohama store. The gold medal has acquired the "gold medal" at the Beijing Olympics and the London Olympics as the name suggests. The surface is more smooth with a golden titanium coating, and is outstanding durability. There is also a difference in color, so you can choose from a color that matches your body, or you can focus on performance. A comfortable ride with a higher -grade cog! 045-413-7875 yokohama@brotures.com