Boucher bits (also known as hanging cheek snaffles and more properly spelled "Baucher," but old habits die hard) are surrounded by a lot of hype and misinformation. It is commonly believe that their large purchase and rotational action engages a horse's poll, and indeed, they are often prescribed to riders hoping to lower their horse's head. Their legality and suitability for dressage is even called into question, since if they have leverage action behind a horse's ears, then they are no longer true snaffles and thus should not be permitted in the show pen. But what is the truth?
Previously, I have uploaded another video titled "The Boucher/Pelham Experiment." Surprisingly, despite the obvious similarities between these two types of bits, the film was met with harsh criticism and accusations that the set-up did not accurately simulate the action of a true Boucher. So, I procured a hanging cheek snaffle of my own and set up a controlled testing protocol to settle the debate once and for all.
At the beginning of the video, you can see that with a cavesson and from a distance, it is very difficult to determine what is happening with the crown strap. However, comparing the location of the headstall concho to the palomino's facial crest shows that no movement is occurring, so the bridle must not be tightening. This is confirmed when one of the cheek straps is replaced by a hanging scale. The scale is tared while the bit and reins are at rest, to read a weight of 0.00 pounds. As the reins are pulled and the bit engages, the latter rotates forward but also lifts in the horse's mouth with cheek stretch. Thus, the scale now records a negative value. Far from increasing poll pressure, the action of the bit has actually *decreased* the force behind the ears--just like every other snaffle.
The same experiment is repeated several other times, using slightly different variations on the theme. On the front view of the Paint horse, the cheek straps visibly slacken as the bit is engaged. On the sorrel, again the weight is recorded and shown to decrease (from 0 to a negative number) when the reins are pulled. In each case, the reins were lifted in an angle intended to mimic the same position that would occur during normal riding (although admittedly this is sometimes hard to see in the video, due to difficulties with both the scale reading and the rider's hands showing up on the screen at the same time).
What conclusions can be made from this? First, bit manufacturers and "popular opinion" are often wrong about the actions of various pieces of equipment. If in doubt, test it yourself. Second, just because the Boucher does not provide poll pressure, that does not mean it is not a useful bit. Some horses may appreciate the stability it provides in the mouth, as it has far less inherent motion than other snaffles.