As you can see from the above illustrations, to ride a correct 5m Loop, (Fig.3) the horse needs to get a little deeper into the corner than for a 20m Half Circle (Fig 4.), otherwise he will leave the track too late and find himself quickly running out of room to make the changes of bend smoothly and evenly.
The apex of the loop is a at point 5m from E (or B) on the quarter line. On the right rein, as the horse leaves the track at K you have to slowly and smoothly change the flexion and bend to the left, so that the horse is bent to the left as he passes E. Then as you head back to the track you once again slowly and smoothly return to the right flexion and bend and continue around the corner in the correct form.
Although this is a relatively simple exercise do not be tempted to force the flexion and bend with your hands. Changing your seat bones, together with the position of your legs, and shoulders fluidly through the movement will allow your hands to keep and even contact on the reins and encourage the horse to continue to seek the bit.
As your horse becomes proficient in this exercise you can move on to 10m Loops and then onto the Serpentines.
The most basic Serpentine, beginning at A or C, is the 2-loop or 2 half 20m circles in the small arena or 3-Loop Serpentine (Fig 5) in the large arena. These only require a smooth change of flexion, bend and diagonal (if rising trot is ridden) over the centreline. However, when more loops are added the way of riding them changes also. In the small arena a three loop Serpentine is ridden as 3 half circles connected by straight lines.