Kettenpflege: Unterschied zwischen den Versionen

[[Bild:Kette_NKVR.gif|center|Neue Kette auf verschlissenem Ritzel]]A new chain on a worn sprocket. Most of the driving is happening on the left side, where the chain first engages the sprocket. Due to the mismatch in pitch, the rollers in the part of the chain that is about to leave the sprocket are doing very little to push their teeth forward, instead, they are being forced upward by the slope of the teeth. Since the teeth/rollers on our left are doing most of the work the load is concentrated on them. In addition, as the roller follows its tooth around the sprocket it rolls up the "ramp," while under load. This promotes wear to the insides of the rollers and to the "bushings" they roll on. With a properly meshed chain, the roller only turns a tiny bit as it rolls onto and off of the chain. [Again, this is a photo of a hanging chain. The links could not ride higher and higher as they come around to the top and still engage the back of each tooth. I still need to check, but I think instead that the links must ride lower and lower as they come around to the top. Indeed, that is what the photo appears to show for the first few engaged links at the right side. If the last link at the bottom of the sprocket rides too high, it lands on top of a tooth, and the chain slips forward when that link comes around to the top. A chain held in place by rear axle position rather than a derailer or idler is forced into engagement with a worn sprocket, but then each link is heavily stressed as it engages. Modern sprockets designed for easy shifting have short teeth. Taller sprockets can develop a hooked shape. It is often possible to flip a worn sprocket over, or grind off the hooks to give it a new lease on life -- not possible though with specially shaped and ramped sprockets, and not recommended with a fixed gear or coaster brake, which pulls the chain in both directions. -- John Allen]