Originally Posted by
Thirstyman
Yes, but they must be done at an acceptably high wattage/effort and you should really only look at time on the trainer. You do need to de-rate the speed and hence the miles as they will be overstated versus what is done on the road with wind resistance.
Ever ridden a computrainer? Every mile on that thing is more work than an "equivelant" mile on the road.