Hey guys, just curious about which DID chain I should get. Currently on the street and on the track in the future. I'm not sure if in the future it is going to be just a track bike or a street bike as well....it all depends on what I can afford later on. I am going to be going 1 down in front and 1 up in back as well. I'm looking at the 520erv2 and 520vm. I can't find anywhere that really tells me what the difference is? faster wear maybe? also how many teeth are on the stock sprockets? thanks in advance.