I have a friend who goes early to spin class and puts on his own saddle instead of the spin bike saddle. He even switches out to his own pedals too. I get a sore tailbone from spin class (yes, history of fractured tailbone 38 yrs ago) and also on my trainer too, with my own comfy saddle. The difference for me must be that on my trainer and in spin class I habitually will sit straight up during warm up and cool down. I can't ride without hands on my handlebars, so I am never in this position on my bike on the road. And my tailbone never hurts from any biking on the road. something to experiment with? Tokie