To execute a proper rollback, we need to first discuss the fundamentals of body position and what your horse needs to know beforehand.
The first and most important thing is that your horse has a good understanding of following his nose. By this I mean that he not just follows with his head but with his entire body. A good indicator of this is when you pull to the right is the horse’s first step with his front right leg toward the direction in which his nose is turned? Once he does this, can you get him to follow with both shoulders and the ribcage, causing him to set his rear right leg ( if going to the right) and pivot on that leg? You need to have the horse doing this on a consistent basis.
You also need to have your horse yielding to leg pressure from the outside leg. This is something that is sometimes overlooked. It is much easier for a horse to be bent to the right and pushed out with the right leg. This is where we begin to teach yielding to leg pressure, but outside leg pressure must also be taught and is just as important. Outside rein pressure is nice to have at this time, but is not yet a must as it is used more in finishing the rollback. However, direct rein pressure is a must.
I first teach a rollback from a back up rather than from a standstill. The reason for this is because I can dictate which rear leg is used to pivot on. If I work from a stop or a standing position, both rear legs are planted and holding weight. However, this is not the case when backing up. How this is used to my advantage is like this ( put your thinking cap on and visualize): When backing up, feel with your seat which rear leg is stepping back. If I am going to rollback to the right, I will feel for the horse to begin to step back with its rear right leg and at that time I will pull with my right hand, only guiding with my left. Don’t do this quickly–rather make it smooth, pulling your right hand first towards you right rear pocket. Once the horse has pivoted 90 degrees, your right hand should be pointing in the direction in which you are wanting him to leave the rollback. Your weight should start to shift forward and your left leg should be encouraging him to push through and into the correct lead.
Once again, I must add that you as the rider should be looking where you are going next–not where you’re at. Look in the direction that your horse will be leaving the rollback, which is 180 degrees from where you started. If you are looking at your horse’s ears, he has no way of knowing where he should be going next. Remember–just like the spin, the rollback is a forward motion maneuver and cannot be performed properly if he is held back in the rotation and sling-shot out at the end. This is the reason: when a rollback is used to work a cow on the fence, in order to not lose ground on the cow, the horse has to keep forward momentum in the stop and through the rollback–if not, precious ground and time is lost trying to catch up to the cow. If forward momentum in maintained, the horse approaches the stop with the inside rear or rear fence leg planted deeper in the ground and is following the cow with his nose. He continues to walk on his front legs, rolling across with his front end and driving out of the maneuver with his rear end. This is different from the cutting rollback because the objective is not the same. In cutting, you want the horse to pivot on the opposite rear leg.