Most people are going faster than they think. 20MPH slide is enough to occasionally put people in the hospital a "sudden dismount" at 15 mph can annihilate you

Most people are going faster than they think. 20MPH slide is enough to occasionally put people in the hospital a "sudden dismount" at 15 mph can annihilate your teeth, or cause severe TBI. Even tripping while walking in the wrong way and hitting your head can lead to death. If you're going slow, you can maybe skimp on some of the abrasive protection, but you should still have something on your skull and joints.