Few pieces of tack inspire as much debate in the barn aisle as the butterfly bit—also called the Kimberwick bit or Uxeter. Loved by jumper riders for its adjustable control yet frowned upon in some show divisions, this D-shaped bit sits at the crossroads of snaffle and curb technology. After fifteen seasons schooling energetic polo ponies, draft crosses in lesson programs, and off-the-track Thoroughbreds, I have seen the butterfly bit turn heavy, leaning horses into soft, rideable partners—when it is chosen and fitted correctly. This article distills that practical barn-aisle knowledge and pairs it with up-to-date research so you can decide whether a butterfly bit belongs in your tack locker.
Understanding the Butterfly Bit: Anatomy and Mechanics
The butterfly bit’s cheekpiece is its signature feature: a wide “D” with two, sometimes three, rein slots. According to a technical bulletin from the University of Kentucky College of Agriculture (UKY bulletin), attaching the reins to the top slot produces direct snaffle-like pressure on the corners of the mouth. Slide the reins into a lower slot and you introduce leverage: the cheeks rotate, the curb chain tightens, and pressure is distributed to the poll and chin groove.
Because rein position changes the bit’s action so profoundly, one piece of hardware can bridge the gap between a mild schooling ride and a hot afternoon of polo or cross-country schooling. Horses that respect light contact can stay in the top slot, while those that lean have a clearer cue when the reins drop lower.
Snaffle or Curb? How the Butterfly Bit Blends Both Worlds
Traditional snaffles apply pressure only to the mouth. Curbs multiply rein pressure but risk over-bending or inverting a sensitive horse if the rider has heavy hands. The butterfly bit, with its mid-range leverage, offers a compromise:
- Direct action (top slot) – Similar to a D-ring snaffle, encouraging lateral flexion and steering.
- Leverage action (lower slot) – Roughly 1.5 : 1 to 2 : 1 ratio, milder than a full Weymouth yet enough to elevate a horse that roots or pulls.
This versatility is why the bit is popular in show jumping, hunter-pace events, polocrosse, and adult amateur lessons where several different riders may share the same horse on a single day.
Mouthpiece Variations and Their Effects
A cheekpiece is only half the story. The mouthpiece determines how the pressure feels inside the mouth. A comparative design study by EquineEquip (EquineEquip whitepaper) identifies three common butterfly mouthpieces:
Single-jointed – Encourages lateral flexion; the ‘nutcracker’ effect is limited by the bit’s flatter D shape, making it less pinchy than a loose-ring snaffle for some horses.
Ported (low or medium) – Provides tongue relief and steadies fussy horses. Because tongue pressure is decreased, the horse often yields at the poll more willingly.
Mullen or solid – A continuous bar offers an even, predictable feel. I favor this on sensitive Warmbloods that dislike movement inside the mouth, especially when teaching beginners who may have uneven hands.
Select the mouthpiece to suit the horse’s oral conformation—thick tongues, low palates, or wolf teeth can all influence comfort. When in doubt, borrow different models from a tack store’s trial program before purchasing.
When a Butterfly Bit Makes Sense
There is no universal bit, but years of arena testing point to patterns where a butterfly bit shines:
- Horses prone to leaning or running at fences. The leverage asks them to shift weight back without jumping straight to a severe curb.
- Ponies in children’s programs. A bottom-slot rein lets instructors help green riders stop safely, yet kids can still ride on a lighter top-slot contact during flatwork.
- Disciplines demanding tight turns at speed—polo, gymkhana, and polocrosse—where balance transitions happen in split seconds.
However, the bit is not legal in FEI dressage or most hunter under-saddle classes because any leverage bit with a curb chain is disallowed. Always check your rule book before show day (Wikipedia rule summary).
Proper Fitting and Adjustment
Even a gold-plated bit can cause rubs if it hangs too low or tightens the curb chain too early. Follow this barn-tested fitting checklist:
Height – One soft wrinkle at the corner of the lips is standard. Too high and the horse clamps; too low and the cheeks bang the incisors.
Curb chain – Adjust so you can slip two fingers between chain and chin with no rein tension. When the reins activate, the cheekpieces should rotate about 45 degrees before the chain engages.
Width – Choose a mouthpiece a quarter inch wider than the measured mouth to prevent pinching. Many butterfly bits run slightly large, so try before you buy.
Spend a few minutes at the mounting block to wiggle the bit, watch the cheeks settle, and confirm that the bridle’s throatlatch is not pulling it up.
Step-by-Step: Introducing a Horse to a Butterfly Bit
Switching bits abruptly can backfire. I ease a horse into the butterfly in three rides:
Ride 1: Familiar Terrain
Attach reins to the top slot, keeping contact soft. The goal is simply to let the horse feel the new mouthpiece without added leverage.
Ride 2: Light Leverage
Move the reins to the middle or lower slot for short intervals—perhaps one transition or a single approach to a fence—then swap back. Notice reaction, adjust curb chain if needed.
Ride 3: Full Schooling Session
Stay in the chosen slot for an entire flatwork session or course. Evaluate brakes, suppleness, and willingness to stretch. If the horse inverts or hides, the bit is either too strong or adjusted incorrectly.
Patience here pays off; I once worked with a draft-cross mare who, after three such introductions, began cantering softly rather than hauling her teenage rider down the long side.
Real-World Experience: Case Studies from the Arena
Polo Pony “Rocket”
Rocket’s downward transitions felt like landing a plane without brakes. Switching from a loose-ring snaffle to a mullen-mouth butterfly (reins on lower slot) shortened his stop distance by half within two chukkas, saving valuable seconds between plays.
Lesson Horse “Daisy”
Daisy leaned on her rider’s hands during beginner walk-trot lessons. By using a jointed butterfly in the top slot, students still practiced elastic contact, but if Daisy barged, an instructor could instantly clip the reins to the lower slot. Daisy’s leaning habit diminished over four weeks without increasing hand severity.
Eventing Prospect “Hendrix”
Hendrix curled behind strong Pelham pressure but ignored a plain snaffle on cross-country. A low-port butterfly encouraged him to carry himself between fences, acknowledging rein aids without tucking behind vertical.
Maintenance and Safety Checks
Bits live in a moist, acidic environment (horse saliva) and can harbor sharp burs if not cleaned. After every ride:
• Rinse under warm water.
• Check curb chain hooks for wear.
• Inspect mouthpiece edges with a cotton ball—the fibers snag on burrs you cannot see.
Monthly, disassemble the curb chain and oil any leather connectors. Stainless models resist rust, but nickel-plated cheekpieces sometimes flake—replace at first sign of pitting.
Common Questions About Butterfly Bits
Is a butterfly bit harsh?
Severity depends on rein slot, rider hand, and mouthpiece design. In the top slot with soft hands, it is comparable to a D-ring snaffle. Lower slots plus a tight curb chain make it a mid-level curb.
Why choose a butterfly over a Pelham?
A Pelham requires two reins or converters that can add bulk. The butterfly is lighter, simpler for youth riders, and offers finer gradations of leverage.
Can I use a flash noseband with it?
Yes, but ensure the flash does not pull the mouthpiece up. I prefer a plain cavesson so the horse can chew comfortably and give you honest feedback.
What size curb chain?
Chain width should match bit ring width. Thin chains can bite; overly thick ones delay action. Stainless 2-link English chains fit most 12–14 mm butterfly cheeks.
Key Takeaways
The butterfly bit is neither miracle cure nor villain. It is a flexible tool that:
• Bridges direct snaffle feel with moderate curb leverage.
• Adapts through rein slot choice and varied mouthpieces.
• Serves disciplines that need adjustability—jumping, polo, lesson programs.
• Requires meticulous fitting and progressive introduction for horse comfort.
Use the insights above, draw on your horse’s feedback, and consult knowledgeable trainers to decide whether the butterfly bit will help your horse balance, brake, and excel in the discipline you love. In the right hands, this simple D-shaped cheek can transform a heavy forehand into an uphill partnership.