It may appear that your chain is Ok when it is actually worn out. Without proper maintenance, it could wear out within a month. To check for wear, put the chain on the largest chainwheel (front sprocket). Then looking at it from the right hand side (with the front wheel to your right), pull up on the chain at the 3 o'clock position. If the chain rises higher than half the height of a sprocket tooth, the chain is worn out and will begin to damage the sprocket.