Ass end of the ground.....it does state to have the bike on the ground and level! Basically that's telling me all 4 wheels should be on the ground and no one sitting on the bike. I never adjusted my bike with the rear wheel/s off the ground.Yes, you want the same on both sides. If you cant get one as high as the other, back off on the other one 1 degree. If you have them different, then your rear sprocket will not be lined up completly with the front sprocket. Just tap it w/ a rubber mallet if needed, and make sure the ass end is off the ground.