i d steer away from old ad astra and T1 geo as a lot of bikes dedicated for bike polo have been made since.
one of the most solid , succesful and long lasting ( in term of game meta not abuse) is the riding in circle, they did their first polo bike a while ago and fine tuned a lot of the geo aspect with time , maybe @morganxvx can say more about this.
now if you look at more recent brands like stolen , a lot of the RC specs are used ( colombis zona tubing, paragon parts)
here is my 2 cents tho
when i came back into polo in 2020 , i bought
-max power 26" ( early versions with 2 options of fork drop outs ) geo is old , as you can see below a Medium frame is a 58 cm top tube , the description also state that it has in mind a short stem to avoid turning radius and laidback position ( back then rear wheel pivot where hot)
i didnt like it , the curving was insane but i could barely stay seated on the bike and would be sent over the handlebars.
All lengths in mm
A few words on top tube length: This frame is designed to give the rider a comfortable, laid back riding position on the bike, without needing to run a standard 100 mm stem (which would increase the travel radius on the riders hands while turning). As the top tube is a bit longer than usual, subtract 25 mm from your normal stem length to maintain your usual riding position. Weight distribution is shifted towards the rear wheel, allowing for easier wheelie-turns.
TT – effective top tube length, measured horizontally
ST – seat tube length from center of bottom bracket to top of seat tube
HTA – head tube angle
STA – seat tube angle
BB dr. – bottom bracket drop
WB – wheel base
CS – Chain stay length
-lightfoot 26" ( V2 i believe , sand / goldish paintjob
-riding in circle but with a new max power fork
i found the RC lighter than the lightfoot but some how similar in geo ( i dont have them handy) i kept the lightfoot tho and sold all the other bikes, i then bought a stolen based on their geo + a few specs from my own geo ( 55 cm top tube / 220mm head tube to compansate with my upright posture)
result is im not “laying” on my bike like a racer but more upright position , lots of polo player prefer a more "diving " position to be faster and down to the floor and have quicker control on the front wheel , i just like my back to be as straight as possible, and have less weight on my fragile wrists/ steering hand.
IMO the most important factor for my polo bike is how stable you can be while turning. for me you can try this by turning your handlebars 90 degree and circle back to 180 while your rear wheel stays somewhat in the same place. the wider the circle becomes, the less effective the geo is for me
to @OhManIAmWorried about bb height 30mm and lesser but the limit is pedal striking of course, if i cant pedal while turning without pedal striking then its not good for me.