Bit making "clicking" noise

I have a younger mare I’ve been training and I have noticed that when I put her bit in during ground work the bit makes a “clicking” noise at the trot like the bit is knocking against her teeth. It’s a large O-ring bit. I haven’t noticed it under saddle but haven’t been on her much with a bit, mostly bride less work. The horse shows no signs of pain, accepts the bit no problem, the bit appears to be fitted correctly, and her teeth are up to date on dental work. This mare is also one who has always let me know with out question when she is in pain/uncomfortable so as far as I can tell it’s not necessarily bothering her. I’ve never heard this before so my question is, is this a problem? Should I be actively trying to fix this by switching bits or is this a training issue? Or is this completely normal and I’m way over thinking this. Any advice is greatly appreciated

If the bit is hitting her teeth then it doesn’t fit. It could be too thick or not fit her the shape of her mouth. I would not continue to use it. You will just create problems.

Is the joint between the ring and the mouth piece particularly loose? I’ve had this happen with a horse that carried the bit for herself and it gave the rings of the bit the opportunity to go slack (for lack of a better term). It would click as she moved because it had the room to do so. To be fair, I do ride with a looser bit than most, but I like for the horses to engage and suck the bit up for themselves, seems to keep them softer and more responsive.

Any chance you are hearing her teeth “click” and not the bit? Once in a while (when he’s worked up) my gelding will “bite” his teeth together at a trot. It seems to be more of a nervous thing. It almost can sound the same as the bit clanging against teeth.

Just a thought, anyway.

Do you have a video (with sound) of what you are describing? It’s possible that the bit is incorrectly adjusted and hitting her teeth or that she is clicking her teeth together. But it could also be that she is just quietly working the bit and you are hearing the movement of the bit’s joints, and that is a good thing.