Trainer time vs real time

An hour is an hour...BUT

that's an hour of active trainer nonstop riding compared to an hour of nonstop road riding.

If you're in the typical road location, with stoplights, stop signs, downhills, you'll have to get more than an hour of outdoor riding to get that same effort.

If you're on a nonstop route with minimal coasting, like the Pacific Coast Highway, and hour is an hour.

Prob about equal.  But trainers can be set up differently (resistance), and rides can be different (flat/hilly/windy).  You can coast or soft pedal down hills to recover, but not on the trainer (most of 'em anyway). If you train by power you can compare total session work, but that's a little harder to do by HR alone (if only because of differences in body cooling with outdoor temp/wind vs stationary fan with trainer).  And there is prob some extra mental fitness gained from the mind-numbing (HTFU) factor in long trainer rides

I cannot say that an hour on the computrainer is as hard as an hour outside.  I never have been on a ride where I never stop pedaling, or stop in general for the entire workout.  Both of the workouts have their place, I think the CT or trainer is much more focused training, outside helps handling skills and helps you to not go crazy.

My coach says if I dont want to do my 3 hour 15 minute long ride on sunday indoors, then I have to do a 4 hour ride outdoors.

Depends on where you ride outside. How many stops, how much traffic etc...

cycleops 2 fluid

I use 1:1 on time. I used to use ~17MPH (ie 50 miles for every 3 hours) on the trainer, but now I just go with my Garmin rear wheel cadence magnet sensor mileage. (Be sure to mount the magnet 180 degrees around (directly across ) from the valve stem to balance your wheel .... errrrr but that's another thread.) Whether I'm going for 1 hour or 3, I usually average about .... 16 MPH on my CO Fluid Pro trainer.

It FEELS like (for me, anyway) that trainer time is more valuable than road time, except for hills ... here in hilly central Maryland it's easy to get 1000, 2000, or even 2500 feet of climbing into a two hour ride. And when I check my logs, and regardless how much time I spend cranking uphill at 8 MPH or descending at 38 MPH or steaming at 18 MPH ... plus Stop signs and barking dogs and whatever ... I usually end up averaging about ... 16 MPH, same as the trainer.