I've had tailbone pain for 20 years. I've broken it several times and I have a very hard time getting comfortable for any length of time. Always shifting around. I just started biking this year and I've struggled with it. You have to sit on your "sit bones" which means siting further back on the seat. Google a picture of it and you'll see what I mean. If you sit too far forward on the seat it pushes on the soft tissue under the tail bone pushing it upwards and gets very uncomfortable. I never imagined I would have to learn how to sit on a bicycle seat (properly) but I did. It's not as bad now but it's still an issue I'm going to always have to deal with (biking or not). I did a 35 mile ride this morning on my hybrid and it was OK. I stopped a couple times for a few minutes and stretched, which seems to help.