You're running 12-52 on a 300?
Do you use first gear?
Just amazed. I found 12-48 rendered 1st pointless for me on a 300 and I ride tight woods. I now have a 200 and have just gone 13-48 on that too. Tried 12-48 and again found I was not using first. I haven't ridden anywhere fast enough to find if it'll pull 6th yet though.