The rider, buying the DIDchain, is aware that he has chosen the best quality product available on the market, traditionally from which he demands reliability, durability and economy of operation. However, it is always advisable to replace the pinion and crown included in the kit even when the profiles of the teeth visibly seem regular. Kinematics, regular winding, chain-profile tooth roller coupling, must be in perfect harmony, to optimize le performance of the transmission. Otherwise the gear damages the chain, le regular joints, accelerate the process of degradation of the crown itself. Normally within the si kits use gears from Sunstar Japan and le chains are in many cases sophisticated or of pihigher quality class than the same DID provided in the first equipment. And that's why the kits DID, represent a safe, reliable, long-lasting reference, recommended by the best experts in the field. This prestigious product is intended for pidemanding users, accustomed to long journeys and who also does not disdain a sporty use of the bike. Pinion: PINION PROF. 36-7164-017 Crown: CROWN - PROFESSIONAL 36-8168-041 CHAIN DID 525 VX G&B 116 JERSEYS 40-1537-116 Related 17-41