Well back in my BMX days I always ran 175's. Now I have 170's on my DH bike and 175's on my Everything else bike. I don't notice much of a difference on either bike. I see lots of 165mm cranks for sale (would be going on a P1) but I dunno if 165mm is too short. Only recently have I started seeing them pop up. I'm 5'11 with no real long length to my legs or anything, just pretty standard in size. Just wondering what size cranks most of you guys run on your 4x/DJ bikes?