Tom Thumb Bits

I haven’t ridden Western since I was a kid, and am wanting to learn about the mechanics of the Tom Thumb. I have heard many say that it’s a low quality and poorly designed bit, but haven’t found much about the actual mechanics that went into depth. I’m admittedly not too educated about Western bits but would like to learn, so I’d like to start out with how the Tom Thumb functions.


Borrow one, hang it from your knee, mouthpiece across your shin bone, curb strap snug around your calf. Pull the reins to see how it folds up! Mouthpiece gets pointed to poke horse in top of mouth, pinching action of sides grabs the lower jaw in a vise-like action between the curb strap and shanks. The harder the rein pull, the more nut cracker effect you get on the jaw/shin bone of leg.

Despite the shorter shanks, it can exert a lot of pressure on the jaw, even with a light pull. Certainly NOT a training bit as it is commonly advertised for using. Not a steady bit for a young horse, because it moves so easily with any touch, weight of reins swinging.

In the past, anything with a broken mouthpiece, was considered a “snaffle,” thus a kindly bit. Horse folks got better educated, recognized that any bit with shanks and curb strap is a CURB or leverage bit. The broken mouthpiece does not work in the horse mouth like a more kindly ring-sided snaffle. We look at bits much differently now, than we did when Tom Thumbs were invented. They really are not a nice bit to the horse. And that is both cheap or expensive models, it is a poor bit design.


As others said, very harsh, tend to fold up in the mouth. I had a horse when I was a teenager who was started in a TT bit, had a frequent head tossing issue. Traded for a snaffle, bingo, no more head tossing. The bit was nutcracker-ing into the roof of her mouth with every cue, causing her to put her head up.

Curb shanks and snaffle mouthpieces just don’t go together. If you direct rein a horse, you don’t need to be using anything with a shank unless you enjoy giving unclear signals to your horse.


I was taught circa the 1960s to call a shanked bit with jointed mouthpiece a broken mouth curb. Which is what it is and aways will be. Snaffle refers to no curb chain/strap not how many pieces the mouthpiece has or doesn’t have. And I never rode Hunt Seat seriously until I was 40 years old so a good many Western folk always knew. Depends on where you were I guess.

Regardless, jointed snaffle being kind is the type of sweeping generalization that gets some into trouble. Taking the time to learn how these bits actually work and learning how to use and train the horse go in them seems to escape too many… as it always has. Marketing has really taken over common sense with terms like “ training” and “ correction” serving as description instead of referencing the bits action. Bad way to select a bit for riders, good way to sell them to the unsuspecting.


Have to say I agree with all you are saying. It just took a long time, lots of articles, some “experts” in clinics, for the current name information to trickle down to the lower level of casual horse riders. They called things by what they recognized. If the mouth was jointed, bit “must” be a snaffle, regardless of the sides! And wayyyy back when this bit arrived, there were very few bits available from catalogs. Nothing hand made in my area, no spade bits or anything unique.

You were SOMEBODY if you had attended a Monte Foreman clinic and bought one of his bits!! Attending a Jack Brainard (inventor of western dressage) clinic I heard his talk on bits. Have to say it was an eye-opener for me!! One of those light-bulb moments when “everything became clear” as he explained how bits worked over a couple hours. I learned so much I thought my head would explode!

I shared bit information with my friends, we all got much more analytical in our use of bits and training horses to work with us. Horse has to be happy with their bit, understand how to use “that” bit, to be happy in their work.


Has to fit them and be on a properly adjusted headstall that fits too…but that’s getting nit picky for some. Amazing how may problems things that fit can solve and how quickly the horse responds.


I see a lot of issues with bit widths. There just is not a selection of wide bits available to choose among, without bits getting rather expensive or needing custom makers . Not everyone has a tiny headed horse to fit. Even many refined looking horses actually wear bits wider than 5 inches. My old 12.2 hand PONY wore a 5 inch bit, not refined at all.

People seem to accept that a bit is “horse sized” without ever measuring their horse’s mouth width, especially newer horse folks. Comes as a big shock when “refined Arab or TB” measures 5 1/2 inches in the mouth! Many other breeds also need bits wider than a 5 inch.


Got to be a contrarian. While I prefer Billy Allen curbs, I’ve used Tom Thumb bits without any issues. They do not poke a horse’s mouth any more than any other curb with a single joint mouthpiece, which means it is rare. As a rule, the folding action depresses the tongue more than it lifts the center, although it can be a problem in a smaller mouth. The Rashid article is nonsense. For one thing, it would apply to a lot more than just Tom Thumb bits. It would apply to ANY curb bit with independent sides, including Billy Allens, Argentine bits, Jr Cowhorse bits, etc! His theory that horses break down the different actions of a bit and then compare them to determine what is wanted is fundamentally flawed. Horses do not ANALYZE bits. They MEMORIZE bits - the total feel of the bit and what gives them relief from the bit.

I’m not a big fan of Tom Thumbs. Most are balanced for a horse who carries his head vertically. Since most western horses do not, the bit is badly balanced for western riding. It will rotate in the mouth under just the weight of the reins until the curb strap engages. This means the horse will lose the "signal" of the mouthpiece and sides rotating prior to the curb strap engaging, giving him a chance to obey before pressure is applied to the mouth. If you want to play with that style of bit, at least get one with curved sides. That will eliminate one of the biggest flaws in the Tom Thumb design.

Most Tom Thumbs are cheap bits, poorly made. As a rule, they have a large knuckle sitting in the horse’s mouth and tend to pick up nicks easier than a better quality bit. Reinsman makes a Tom Thumb bit that is well made, at least, but the majority are not.

And Tom Thumbs DO have a knuckle in the middle of the mouthpiece. Lots of other curbs bits do too, and I dislike that design because it can poke - rare or not, it CAN so why use it?

But I have used it with a total of 4 horses just to see how they would respond. All of them did fine. None of them tossed their heads, acted confused, etc. Just moved it a little in their mouth and quickly figured out what to do based on their memory of similar feeling bits. And rode fine. If you ride with slack much of the time and don’t yank hard on the bit - which no rider should do except in rare emergencies - then a Tom Thumb bit is…OK. Not horrible. Certainly NOT the cause of most of the problems associated with it. Those problems are rooted in bad riders applying pressure and not giving relief, or in yanking the reins - both serious sins! Ride a Tom Thumb with a light hand on a horse who has been taught how to get relief and it will work fine.

There are better designs. If you have a horse who already likes a Tom Thumb - and I know a couple - then nothing wrong with continuing to ride him in it. But if you are looking for a good bit, try something better. I like both solid low port curbs and Billy Allen curbs. If you want a broken mouthpiece in a curb, look for one with TWO joints instead of one. Look at the balance - the bend in the sides should match the angle the horse normally carries his head.

It doesn’t help that some riders buy a Tom Thumb in hopes of teaching their horse a lesson via intimidation and force. But that is part of bad riding, and most of the issues seen with Tom Thumb bits are caused by the rider’s bad riding.

Also: The length of the sides has nothing to do with the mechanical advantage of a curb bit. The mechanical advantage is based on the TOTAL length of the side (cheek) divided by the purchase (upper length).