The biggest misconception about Standardbreds is that they don’t canter or gallop; in reality, only a few of them don’t. They have the same ability to perform the canter and gallop gaits as any other horse, but often from their earliest training they have been strongly discouraged from doing so. Most will canter readily after patient and consistent training and can even become fine riding horses. The breed typically has a longish back with hind legs set farther back on the body than most horses. This conformation is most efficient for fast, streamlined, horizontal forward motion rather than elevation. Since the canter requires the hind legs to reach forward and propel the body upward.
I recommend you start working with your horse from the ground. If he has trouble performing a canter in a round pen or on a longeline, he’ll surely have trouble with it under saddle. When your horse demonstrates solid ground skills and steadily picks up a canter on the longeline, you are ready to try it under saddle; however, don’t rush to get to this point. All the time and effort you expend on the ground gaining muscle strength, flexibility, obedience and trust will pay off under saddle.