Today, I did a volunteer session at the Milton Velodrome. I lead out the Try The Track group, and stuck around to keep the Re-cert group "honest". I heard those immortal words again: "I'm dumping my trainer for track". What a bad idea.
With all the excitement over the opening of the Milton Velodrome, I'm sure that is a thought many riders have. I even know guys that race that have circumed to the excitment are fighting their way into any session they can get their hands on.
In fact, it was the same thought I had over four years ago when I joined the Forest City Velodrome. Trainer? Who needs it? I can just ride the track. I hated riding the trainer. It was pure drudgery. I also ran sessions at the Forest City Velodrome on weekends so I could put my own music on when I rode around. It was a lot of fun, but the only thing that this unfocused training did was make me slower. Let's face it. When the sessions are open to do what you want, you can choose to ride or not. That was the problem. It was too easy to sit around and chat or if on the track, it was too easy to go easy. There wasn't any goal to the ride.
With the trainer, one has a goal, a purpose, and a workout to complete. The same goes for structured training on the track. You have someone blowing the whistle and calling the intervals. It's hard go just go easy when you have a reason to go hard. Further, you have a goal - a power number to hit or a heart rate value to get to. That is hard to do on the track because you are largely at the mercy of the other riders or you are drafting. Training has to be purposeful. There has to be a reason for it.
If your fitness goal is to be able to keep up with the group ride at your local club, then maybe you can replace some of your endurance work with the track, but if you race, you are just wasting your time. Insomuch as just riding around outside on the road makes you slower, so will just riding around at the track. It took me two years to figure that out.
A combination of workouts on the trainer, on the track, and on the road make for a skilled fast racer.