Polo Rules

43.86. GI is the diameter and development is the circumference. So just divide by π and convert to inches.

I think that's a bit too conservative. On larger courts I can see 45 or 46 being sensible. I assume there's a matching limit to the size of courts in that rule set.

i just dont know why they would stadartize the gearing!
If I had the legs to ride 50ish and still sprint fast enough, i would!

I can't see the point of standardizing the gearing. Anyway, Irish Grass Polo rules again:

Article 1 – Dimensions of the field
1.1. The field shall be rectangular. The dimensions may vary as follows:
Length: Between 80 and 110 metres (87.489 yards and 120.297 yards).
Width: Between 40 and 70 metres (43.744 yards and 76.553 yards).
However, it is recommended that the field’s optimum measurements shall be 100 metres (109.361 yards) in length and 60 metres (65.617 yards) in width.