I never worried too much about numbness, because it has happened to me occasionally over the last many decades and no body parts ever stopped working. I have had tailbone pain because of the trainer. Not having that problem right now, but the first week this trainer season was bad. I didn't do anything to make it go away. I had previously put the same kind of saddle on my trainer bike that I have on my road bike. Right now, I'm very close to assembling a rocker plate with fore-aft movement. I hope that does away with any possibility of tailbone problems.