I got a flat today. It was the rear tire of course, & right after I freshly oiled my chain. I took the tube out & carefully inspected the inside of the tire only to find the culprit: a small pointy sharp rock from a creek crossing I just crossed. I'm glad that I carefully inspected the inside of the tire for had I not, the new tube would have surely flattened. Just a lesson to remind everyone to carefully inspect the inside of your tire after a flat. Blue Loctite is your mountain bikes best friend too.