Inspecting for frame cracks is especially important on mountain bikes with aluminum frames. This woman is inspecting the area where the seat stays connect to the main frame triangle. I asked her why she was doing this in the nude, in the middle of a fire road, and all she said was that she was hot so she had taken off her clothes, and that the bicycle was making a noise back near the seat stays. They don't call it California for nothing. She was on her way to nearby Muir Beach, which is a popular nude beach, but I had never come across a nude bicyclist before (I understand that this is common at Burning Man, but I've never attended).