This issue comes up from time to time and there is disagreement about it.

I do count trainer and spin miles in my cycling log, but I agree it is hard to relate them to "real" riding. As to "claiming" these miles, there is nowhere to file such a claim and no convention on it, so I just satisfy myself. In some ways trainer/spin time is more productive than "real" miles anyway.

Time on a spinner or bike trainer, for me, is time to do something difficult and pretty intense and specific. This is always done during the most severe months of the winter when "real" rides are difficult to impossible. I seldom ride a spinner or bike trainer for more than one hour, and VERY seldom ride my bike less than one hour so indoor miles account for a very small, but productive, percentage of time spent pedaling. So, yes, I do count them as a small but important part of my cycling life.