10/10/2025
Bit thickness matter more than most riders realize.
Thicker bits (18mm & greater) can spread pressure over a wider surface area, which in theory is gentler, but only if the horse has enough room in their mouth. Horses with a low palate or large tongues, a bit that's too thick can cause constant pressure and discomfort.
Thinner bits (14mm & less) tend to leave more space in the mouth, but concentrates pressure which makes them feel sharper. These suit horses that have limited room or need clear rein aids.
The sweet spot for bit thickness - in my opinion, is 16mm. Most horses can accommodate the width without adding undue sharpness. However, it's important to look at each horse individually.
My own horse, for example, came to me with an 18mm bit. After examining his mouth, I felt like it was too much so I tried several thinner bits with similar mouthpieces. The jokes on me, he prefers an 18-20mm mouthpiece (although I did change the mouthpiece shape). His mouth is quiet, and he stays even in the contact. Anything thinner, he chews, chomps and falls behind the bit.
