Does anyone have recommendations on what to try with a light-mouth but strong gelding to encourage flexion? I'm not great with bits, but am looking for an option for my gelding on the pattern.

I normally ride him off pattern in a Stubben EZ control (below), he seems to to like the 3 piece. I sometimes ride him in a chain mouth Molly Powell "Freshman" bit (below below), and he does alright in it, but stiff to bend. 

Thanks!

An O ring snaffle should work. Hands encourage flexion with feel and timing, the bit has very little to do with it.

Similar to your Stubben, this is one of my go-to training bits. It's a JP Korsteel hunter dee. They make an o-ring as well, but I actually prefer the hunter dee for lateral flexion. O-rings work really well too, but something about the hunter dee feels better in my hands.

For shanked bits, sometimes a chain mouthpiece with a port works well. You can find all kinds of different port sizes, shank lengths, with or without a roller, etc.

Lianna, I agree, and I'm not trying to use the bit solely to increase flexion. But, it's an aid that I use when asking for it (along with legs, seat), and I don't want him to resist the bit or stiffen when he feels it, if possible.

Whinny, thanks, I'll look at those. He does prefer the D-ring over an O-ring, and he likes the 3-piece. I've thought about trying a chain with port, and will think about that more.

Thank you!

IMO it doesn't matter what you ride your horse in -- it is your "leg" that encourages and creates the flexion.

Agreed.. I often go back to an o ring when I want to work on something specific.  

I'm not bit guru and I will never claim to be but i'll add this to the convo. I just recently switched my 5 year old to a 3-piece dogbone simplicity bit and so far im really liking it. I made my first run in it this past weekend and it was probably the smoothest run we have had out of the 4 times I have entered her. She is really easy to ride so I had been riding her in a loomis gag but it pinched the sides of her mouth so bad that I needed to find something different. I will say that it doesnt have much lift (in my experience) so if you have to help your horse alot, it's probably not going to work. And it doesnt have the best brakes either. I ride my finished mare in a tender touch and I love that bit. It has been the best thing for her. I get plenty of flex out of it and it gives me really good control of her shoulders. I tend to want to drop my hands early and it lets me keep her picked up so we dont crash barrels.

Simplicty:

Tender Touch:

My young one is really good about leg pressure and flexing. However, I rode her in a hack a few weeks ago and it was like riding a broomstick...so while you are correct, the bit does have a role.

Thanks. I have a tender touch that my daughters mare works well in, and I haven't tried it on him in a bit. Maybe I'll throw it on and see. Thanks for the simplicity too, I'll think on that.

This guy is sensitive. I'm not trying to fix a flexion problem with a bit, but I notice more brace with certain bits, so I'm trying to eliminate that if possible.

I also use the tender touch, my mare is very sensitive and this bit she loves.