By Fiona Dearing, Bit Right Equine Bit Fitting
Welcome to 2025! I’m looking forward to sharing more information about bitting with you this year.
This month we’re going to look at a very commonly believed bitting myth. This is information we may have heard over a long period of time and have accepted as ‘true’. Some information we’ve held onto over the years is actually quite old knowledge and has become outdated as we’ve learned more about our horses biomechanics, welfare, and both the design of and pressures bits apply.
This myth is one I grew up with myself. How many of you have heard the line the thicker the bit the kinder it is? I regularly see horses in fittings with bits that are sometimes up to 20mm thick through the diameter of the mouthpiece. Often, the horse is unable to close his or her mouth around the bit comfortably. This also means the horse is unable to ‘hear’ your aids clearly. The old thinking around this particular myth is the pressures of the bit are spread over a larger area of the mouth with a thick mouthpiece and therefore it was kinder for the horse.
Of course we can also go too far in the opposite direction which is why all associations have rules around bit diameter. The minimum diameter bit allowed in Pony Club is 10mm.
Our modern studies have shown us that horses actually don’t often have much more than 14-16mm of interdental space to place a bit. If you’re looking at a pony or a fine faced horse like arabians, riding ponies etc then that space may be smaller again. With each horse we look at we need to take into account the facial structure, size and type of tongue, lips and bars (lower jaw) when we consider the size and style of bit we choose for them. These characteristics will also vary widely across breeds.
If you’ve an older style bit take note of how it sits in your horse or pony’s mouth. Can your horse or pony close his or her mouth comfortably around the bit? If you’re looking at something similar to this photo (attached) your bit is too large in diameter and likely to cause discomfort and miscommunication.
There are many other things around your bit to consider for your horse which we’ll look at in future articles however this is probably the biggest myth of old learning I see adhered to. Most modern bit manufacturers have their diameters no larger than 16mm with many offering sizings in 10mm (for tiny mouths) – 14mm also.
Next time you’re in someone’s old stables have a look at any old tack that may be on the wall, I guarantee you’ll find a big old thick bit up there, hopefully covered in cobwebs and no longer being used.