Is your primary chain drive louder than you think it should be? The Sur-Ron Light Bee frame varies over time and when you install a primary chain drive you may find that the alignment from the motor sprocket to the primary driven sprocket may be off. This causes a lot of noise and premature wear on the sprockets and the chain. Bring those sprockets back into alignment with the db Dirty Bike primary driven sprocket shim. Shims are 1mm thick aluminum and most bikes usually only need one shim. Shim goes in between the driven sprocket and the jack shaft. See the installation instruction page for more details.