There are a few questions that I get asked time and time again, so here' s a series of "cheat sheets" for you to give you a place to start. Please keen in mind, that these suggestions are general, and do not take into account the details of your exact situation. Use them as a guide, read the product descriptions of the bits listed, and consider them as they might apply to your particular issues and training that you are also undertaking.
Cheat Sheet #2- Bits for Starting or Retraining Horses
Your green, young or uneducated horse is like a blank canvas- it's actually a huge responsibility for you. No horse is born with a "hard mouth". Poor riding or training create one, just as good riding and correct training develop a responsive horse to the rein aids. I do not like the term "re-mouthing", again it's not about the mouth, it's about re-educating the horse to respond correct, to understand what we are asking of him.
If you are sending your youngster to an expert trainer to start them off, then I recommend you ask them what bit they prefer to use and why, and if possible carry on your process with the same or similar bit until you find you need to change. This offers some continuity for you both.
If you are starting the horse yourself, then it largely comes down to your preference and your needs. Consider what sport of discipline you have in mind for your horse in the future, and use that to help guide your choices. Keep it as simple, stable and as generous in terms of weight bearing surface as you can.
Be wary of the very fat, hollow mouthed bits. They are too fat for most horses to be comfortable, and the lightness of them does not help you transmit clear aids to your horse. A mouthpiece around 16mm is a great place to start, and 14mm is the thinnest permitted for young horse dressage classes- and most trainers would not use anything thinner than this on a green horse.
I generally suggest the use of the eggbutt or other fixed cheek- you can read more about the benefits of this over a loose ring bit on my previous blog post here.
Remember, whatever bit you use is only as effective as your training. Horse are not born with an understanding that they should soften to the rein aid, that they should move this way to follow an open rein, or that they should stop when you apply a little stronger pressure. It's a language that they need to learn, and as with learning any language, this takes time and patience.
The Nathe Snaffle
This is a loose ring bit, but the solid plastic mouthpiece keeps this bit sitting very still and steady in the mouth. It can be a nice bit to start in, as your aids are very direct, there is not a lot for the horse to play with and the slightly bendy plastic can be more forgiving than a metal mouthpiece.
A lovely bit, very nicely weighted, and with a flatter eggbutt cheek to sit more like a dee. The very pronounced curve also helps to keep this bit still and steady in the mouth. The 14mm version of this is quite generous, and more like a 16mm in other brands.
The Nathe Snaffle and the Sprenger Dynamic Eggbutt
The Minos Vision Balancer Dee
Gentley curved, with a mouthpiece along similar lines to the loose ring Team Up. Again, this bit is nicely weighted, the slightly larger dee rings sit flush against the sides of the face, giving the rider the benefits of full cheek, but without the worry of the pointy bars. This bit will sit very even and steady in the mouth, and the copper alloy will mean it will nice and warm.
The Sprenger Eggbutt
The classic- a simple single jointed eggbutt. 16mm thickness with a lovely weight to it. The single join is much maligned, but a lot of horses do simply go better in them than a lozenge style, so it is not to be discounted!
The Balancer Dee and Sprenger Eggbutt
The FM (Fulmer) Snaffle
Along the same lines as the classic eggbutt above, the FM bit (below left) while having the loose ring is very popular for starting young or green horses. You can add FM keepers to steady the mouthpiece further should you wish, plus control the full cheek bars a little for safety.
The Neue Schule Pony Full Cheek
One for the ponies! This is quite a fine mouthpiece at 10mm, but for most of the smaller ponies this is a very comfortable thickness for them as they simply do not have as much room between the upper and lower jaws as the horses do. The stability of the full cheek is useful, though the cheeks are scaled down and smaller to suit the more delicate pony head.