Which bit should I use?

You should try a good old loose ring Snaffle. Mildest bit out. If that doesn't work, try an eggbutt, they are mild too but slightly more harsh then a plain snaffle. If your horse doesn't respond to either of these bits, maybe you should consult your trainer or local saddlery.

To be honest, people on here will tell you tom thumbs are the worst things known to man. But I say heck with it, if the horse likes the bit why not? And they're not bad if you use them correctly, when I rode Dakota western I used a tom thumb.

Anyway, try an eggbutt snaffle. You want to keep her in something nice and simple for now. An eggbutt will "muffle" the movement of your hands a bit and some people swear by that technique. If she doesn't respond to that try a loose ring snaffle, it will give her direct contact and it does not muffle your movement at all.

Good luck!

i would definitely discontinue using the tom thumb. very bad bit. im not saying that only because its harsh; there are many other problems with this bit. theres a reason so many people will tell you not to use them. i used to use one too until i read this link

http://www.todayshorse.com/Articles/TroublewithTom...

i really suggest reading this. its a great article and very informative. it explains how the tom thumb works and what the problems with it are.

as for what bit you should use, i would stick with the d ring or an eggbutt snaffle. i know you said she doesnt really respond well to it but you just gotta keep working her in it and get her responsive in it. youll get there, it just takes time. i would do alot of pressure and release flexing and stopping with her in the snaffle so she learns to really give to it and understands it.

i dont like tomb thumbs just because it makes my moms horse a ***** to ride, but thats my own personal experience. We now have her in a snaffle and she is so responsive to it.

I think if you start riding with a snaffle for a while it might grow on her. That is the most mild bit there is, other than no bit at all. It might just take time for her to get used to what you are asking her to do. I personally rely on snaffles, and i like to ride with no bit at all. A horse that you can do that with will usually be really responsive to rein cues.

Sweet iron loose ring French link snaffle (or a variation of the French link/oval link/lozenger link mouth piece, you can get the middle piece plain or copper, eggbutt, loose ring or full cheek sides)

Sweet irons yummy

Loose ring sits well in mouth, bars not to thick that she'll lean on your hands, but not thin enough to be harsh (I find eggbutt snaffle bars are thick and muffle too much, my gelding leans on my hands in my eggbutt, 17hh is alot of leaning, I've switched him to suggested bit and it's amazing).

French link is a soft 'nicer' mouth piece than an ordinary snaffle, alot of horses have issues with the nut cracker action of the ordinary snaffle, it bends in mouth when you use your hand aids, presses on top of horses mouth, some horses flick their heads or pull on the reins to try and stop it. This is only some horses that have an issue with it though.

i have an appendix so i use a tomb thumb copper roller grazing bit for western . i tried using the same thing but a D ring for english , but i had no brakes ! haha . i told my trainer and she handed me a kimberwick . its not a harsh bit whatsoever its just a step up from a tom thumb . this is a pic of what i use . http://www.lazybgeneralstore.com/servlet/the-343/K... . the chain you see goes under the chin .