I cleaned and oiled my chain today and while I was at it had a close look at the rear sprocket to see how worn it was because I was told it's good to check on it every now and then. Thing is I have no idea what to look for. I have got a picture here: Dropbox - IMG_20160416_163430384_HDR.jpg It was taken after cleaning the chain but before lubricating it. Is my sprocket okay? Also what should I be looking for?