I'm getting back into dirtbikes after 20 years now that my oldest son (8) is starting into it. I picked up a '97 yz250 yesterday. It needs the chain & sprockets replaced. 13-49 with a 520 DID chain right now. I read up in the Tech section & searched some threads to try to get up to speed. I won't be racing, mostly goofing on my property & hitting the local spots with my son...some tracks, but just for fun. We do have a place in Michigans U.P. which gives me access to tons of two tracks, fire lanes & wide orv trails. I don't plan on much tight stuff ever. I'm looking for a gearset to make it a little more manageable down low for someone like me. I don't need to win any holeshots. I've really barely ridden this yet, just going thru it all first. This may be the right set up for me, I just really don't know. Also once I choose a set, is there anything wrong with going with the cheaper priced sprokets and chains for my usage. Or are there ones to definetly not use. In reality it will be alot more easy riding than any hardcore action. And what's the deal with the o-ring vs heavy duty? I would assume I'd use an o-ring right? Thanks for the help.