If you are pulling the bar into your shins off the floor, your back angle is too vertical. Raise your hips so that the bar can come up in a straight line.
In SS, it is recommended that the bar touch the shins, feet planted midfoot (using the shoelaces as a guide). If I am pulling and cutting my shins up (bruising them too), am I not pulling vertically? Also, from the start position are you supposed to tighten your hams and press down INTO THE FLOOR as the bar rises past the knee? I'm still trying to understand the below-the-knee mechanics of the exercise.
If you are pulling the bar into your shins off the floor, your back angle is too vertical. Raise your hips so that the bar can come up in a straight line.
Below the knee the hips rise with the shoulders. This means that the only significant motion of the hips is straight up and back angle should remain the same until the bar passes the knees.
Initially the knees are above the bar and, if they did not move, the bar could not travel in a vertical path. The hips rising with the shoulders and not producing significant horizontal movement allow the knees to extend as they move posteriorly causing the shins to become vertical and moving the knees out of the way as you pull the bar off the ground.
Essentially its knees around the bar, not bar around the knees.
If you are in the correct starting position then when you press with the heels, the bar will move straight up and "gently" brush your legs.