WHEN YOU introduce the horse to the double bridle there are some important factors to keep in mind. Correct use of the double will lead to improved collection and self-carriage. However, using a double bridle too soon can result in anxiety in the horse, mouth problems and irreparable damage. So always consult with an experienced trainer when introducing the double bridle for the first time.
The double bridle should be used to refine and finesse communication between horse and rider at the higher levels of dressage. When you have completed the training and work required at Medium level, and the horse is willing and able to carry his weight on the hind legs with uphill balance in the snaffle bridle (a good way to test this is to ride a simple change: a clear transition from canter to walk and back to canter without any loss of balance or trot steps in between), then it’s a good time to introduce the double bridle. You never really have to use a double, but at this time it’s possible.
The double bridle is made up of the Bradoon bit and the Weymouth bit, or the snaffle and the curb. The snaffle influences lateral and longitudinal flexion and can elevate or open the frame as well as bend, supple and direct the horse’s neck left and right. The curb influences longitudinal flexion, causing the horse to give his neck and bring his head toward the vertical line, also referred to as closing the frame. The curb lever should pull to 45 degrees when the curb chain is engaged. More than that, and the port will be putting too much pressure on the roof of the mouth, so ney ney.
The neckpiece of the bridle puts pressure on the poll due to the mechanics of the lever of the snaffle. Horses with a very sensitive poll may be more comfortable in a padded neckpiece. I use Stubben’s Switch bridle on all my horses (it’s a snaffle and a double in one), as it’s ergonomic with the pressure points most performance horses does well with and no unnecessary extras.
Hope that helps!