Back to Basics - how to measure a bit

Today we are going back to basics, its always the best way to start when bitting. 

Whether you have a new horse or you're trying a new bit it's vital to know what bit fits the best. You do not want the bit to be too small or too big. If the bit is too tight it may not act in the way it should, creating unwanted pressure within the mouth and potentially rubbing the side of the mouth or lips. Which can create even more problems. Equally if a bit is too big it will flop around in the mouth, hit teeth,  or move around so much it can create bruising and not sit correctly in the mouth. 

Many many people come into the shop or even message me online and ask for 6.5 or 7" bits. This always throws up a red flag as these bits just aren't made as standard by most manufacturers. 

So where do you begin if your horse has come with a bit or you're bitting for the first time?

Already have a bit

Firstly, if you have a bit already with your horse then to measure it you can simply get a ruler, a stiff measure is always more accurate than a soft tape measure. I prefer to use a steel ruler where the start is at 0 rather than one where you have space before the 0. 

This image has been taken from Neue Schule and demonstrates how to measure the width of the mouthpiece clearly between the rings. I see so many people measure from end to end and then request a larger bit size than needed. 

This diagram also shows how to measure the thickness of the mouthpiece,  generally this will be 10mm 12mm 14mm or 16mm. 18mm and 20mm can be common in plastic bits, I.E nathe and sprenger metal bits can come very thick too. The rings are also measurable within the centre of the ring, for example Neue Schule commonly make 55mm for bradoons, 65mm for ponies and 70mm as standard bit ring sizes. 

Bitting for the first time or from scratch

If you don't have a bit for example you're bitting for the first time, you'll find many bit sizer tools on the market and we stock the bombers mouth measure for hire. 

This is a non invasive method and you can simply slip it into the mouth and over the poll, as if it was a bit and bridle. Simply slide the cheeks so they fit snug within the mouth and then you can take it out and measure between the cheeks. This gives a more accurate reading as you can fit it to the height and position in the mouth required. 

Alternative methods include, using a string or a wooden spoon and a maker pen, if your horse allows these into their mouth. This can be very fiddly especially if the horse doesn't stay still or like the foreign object in their mouth. 

Getting the size right

Bits are generally measured in .25" increments from 3.5" to 6.5" with 5" and 5.5" being the most common size. X.25" and x.75" bits are quite hard to come by in more 'generic' steel bit brands (generally cheaper brands). You may come across some brands that are generous for example Korsteel that say a bit may be 5.5" but in reality it measures 5.75". Some brands will use mm where 125mm can be classed as 4.75" or 5" depending on the brand and 130mm being a true 5" and 135mm being 5.25" and so on. 

Do always remember that when you measure you're measuring in a straight line across the mouth therefore this is the size you'll need in a straight bit. For a single or double joint, to allow for the action of the bit, you should increase the bit size by 0.5" from straight and with a waterford you should increase by 1". This works in reverse so if your horse wears a 5.5" jointed snaffle and you choose to go for a non jointed bit then you should go down to 5". 

That being said please do bear in mind that some bits are more curved and anatomically shaped and typically come up small, for example the Neue Schule Verbindend, in this bit you should go up at least 0.25". 

Finding a bit that fits and is right for your horse isn't as easy as just walking into a shop and picking up a bit the size you've measured. There's so many more factors to take into account. This will be discussed in my next blog. 

Thank you for reading. If you have any questions please get in touch! 

The Bit Doctor. 








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