Had a question about the amount of effort on the trainer and how it translates to the street.

This is my first winter using a trainer (kurt kinetic road machine.) I have the box thingy in front to
adjust wheel height, which is set so the bike is at a slightly uphill pitch. I've finally been able to get up to a steady 90 rpm cadence over the course of an hour or more which I feel is great progress, as last year was my first season and had no measuring tools, or computers.. I just road as hard and fast as I could.

Riding on the trainer though, it seems like quite a bit of effort just to maintain a 17mph avg. Assuming I put this same amount of effort on the road, would I be any faster, slower, or roughly about the same as the trainer? Just curious what everyone else has observed.

I generally train for about 50-55 minutes with a few harder 'intervals' of work thrown in to make break up the monotony. (eg. spin at 120rpm for 1-2 minutes, or drop to a lower gear and try to maintain 90 rpm for as long as I can)