30 mph for 24 hrs on a "static" bike? Does this mean a trainer?

Are there multiple riders on multiple trainers so that switching timing/measuring from one rider to another there is no time lost at the changeover? Or is time spent dismounting and remounting not counted?

If only one bike, are all the riders the same size so no afitting djustments are made? How long is each interval? Is there a link to get more information?