I've fallen off of motorcycles and bicycles many times over the years wearing jeans, and every single time my ass has contacted the pavement, and almost every time my jeans tore. To this day I have several "tattoo" of fine rocks on my ass and my lower back from asphalt bits being ground in. I have big ass (no pun intended) scars on both butt cheeks. Chunky yes your butt maybe the biggest muscles in your body but after about two weeks of changing blood and puss soaked wound dressings, a tearing the hair off of your cheeks with medical tape, you'll be wishing you had a good pair of riding pants on. Chaps may help on a chilly day but that is it.