This is one of my favorites. Back by popular demand... Meet 'ole Tom Thumb. I like to pick on this Tom! :) When I was a kid back in the '60's in Essex County Ontario, almost every rider was using this bit. I remember my Dad having this bit. Before I get started on why this is NOT an effective bit, I want to point out to you an article I did on my website on the history of bits to refresh your memory on why we use bits. History of Bits. (www.reinersuehorsemanship.com/2009/03/history-of-bits.html)
Bottom line is: It's about communication. I've been fascinated about bits for decades. If you want my take on busting myths and disinfo on bits, I would highly recommend you search for the numerous articles I've written on my website www.reinersuehorsemanship.com for more information.
Will The Real Tom Thumb Please Stand Up
A lot of people still use this type of bit - at least in my area here. It's generally called a transition bit - transitioning a horse from a snaffle bit to their first curb (or leverage) bit. I would call it a 'stuck at this level' bit. Is it a 'training snaffle' - even though it's not a snaffle at all!? It's technically in the category of a 'combo' type of bit. I will do a separate series on combo bits soon. I really like combo bits.
I remember doing a bit evaluation many years ago for a local lady rider and her father showed me a tom thumb training snaffle - similar to the one shown at the end of this article (only not with the copper roller in the middle). I told him jokingly how I use those types of bits for wind chimes and/or toilet paper holder decorations! :) I kid you not! He had a really shocked look on his face but it got him thinking!
a Little Bit Better
The original Tom Thumb bit is not effective because of the jointed mouthpiece (any bit with a jointed mouthpiece) will have the now famous 'nut cracker' effect. I really hate this. It causes pain. This bit was made a little bit better with the addition of a copper barrel in the mouthpiece to prevent the bit from having the nutcracker effect and with the shanks being slightly curved back.
So if you're going to stay loyal to Tom, I would suggest getting the version that has the copper roller in the mouthpiece, the curbed back shanks, the 1/2 rings on the shank (to make it a combo bit). And of course the curb chain (not shown).
Good luck in your relationship with Tom.
Putting My Spin On Curbs Bits Who Want to Be Snaffle Bits