This might be too personal to talk about on a blog. When I sit at my wheel for a few hours, the ends of my pelvic bones get sore. The soreness turns into numbness, then the numbness travels down my legs. It's really painful. My throwing chair is small and contoured and I didn't think I could find a cushion to fit. Someone suggested that I try wearing bicycle shorts. All this did was remind me why I don't even like wearing bike shorts while biking.
I dug through my closet and found some small shoe insoles, the kind that are designed to go under the balls of your feet when wearing high heels. They are made of a grippy gel-like material, so they stay put in your shoes. Turns out they stay put on my throwing chair too. I've been sitting on them for five days now, and no pain! Relief from numb butt!