Debunking Bit Fitting Myths - The Two Wrinkle Rule

Tammy Levasseur

Posted on February 01 2023

Debunking the Two Wrinkle Rule - On The Bit Lorinery Solutions
Most of us have been taught to adjust our bridle cheek pieces until we see two wrinkles at the corner of the horse’s mouth. For decades, that was the standard for fitting.

However, in 2023, we would not consider the Two-Wrinkle Rule to be a proper metric to gauge bit tension.

Back in the day, bits were not anatomically designed. Basically, they were symmetrical and the rotation of the bit did not matter. Therefore, the old school method of looking for the wrinkles at the corner of your horse’s mouth was more appropriate because contact applied to the rein that rotated the bit made no impactful difference in how the bit was situated in the horse's mouth.

Modern bits differ greatly in both form and function. Today’s bits are designed more anatomically and with the understanding that the bit will rotate in the horse’s oral cavity upon rein contact. When a modern bit is properly tensioned, the bit will properly rotate in the horse's oral cavity as it is designed to do.

Therefore, with modern bits, two wrinkles do not necessarily indicate good or poor fit. In the absence of measurements of a particular horse’s oral anatomy, two wrinkles would generally be a decent assessment for older bits. With modern bits, not so much. What we all learned (and what worked) a few decades ago does not apply to modern bits.

Interestingly, with a more modern and anatomical bit, we find the importance of a scientific and measured approach to fitting your bit to be even more essential than was historically the case.

If you have any questions about this subject or would like help with your bit and bridle fit, please feel free to email

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