In order for you to choose the best sprocket set, you must determine what you require the sprocket to do. When choosing a sprocket to drive an implement, the speed required for proper operation, the amount of torque desired and the size chain you need to match the sprockets to are all important in choosing the best sprocket set. The condition of the sprocket teeth is of major importance when choosing a used sprocket set. Any worn teeth or bent teeth can indicate a sprocket that has been misused or abused, and you may wish to avoid using the sprocket for anything other than a back-up sprocket.
Chain is sold in sizes as well as pitches. Matching a sprocket set to a chain requires both the tooth size and pitch to be known. You may wish to avoid any sprocket set that is not marked for size and pitch. The teeth on the best sprockets are uniform in shape and design; finding a sprocket that has wear on one or both sides of the teeth indicates a poor sprocket. You will want to check the sprocket teeth by pressing your finger against the tip of the teeth. Any tooth that appears or feels sharp is worn and is not the best choice for a long-lasting application.
One of the first things to check on a sprocket set is the color of the sprockets. Any set that is of different colors may be a mismatched set and should be avoided. The reason to avoid mismatched sprockets is that the set must have been damaged or sufficiently worn to warrant breaking up the set. The same can be said of any sprockets that have different manufacturers' names imprinted on them. You will want to find a matching set of sprockets when attempting to find the best set possible.
It is also wise to examine the sprockets to verify that both are of the same thickness either by measuring, using a micrometer or by holding the two beside each other and visually inspecting them. Once satisfied that the sprockets match, the teeth are good and the pitch and size is correct, you will want to examine the inside of the sprocket to ensure the key way or splines are in top condition. Small nicks and scratches can be filed or polished out of the inner areas of a sprocket set, however, damaged key ways or splines are more difficult to correct. It is also important to choose a sprocket set with no stripped threads or bolts.