Brushless Gearing Question

[Gustav]

Dafni's using the equivalent of 14/51 with the 7xl/9920
on 14 cells with nice low temps.
That works out at about 18.3:66 so your 19/66 should be a very good starting point.
I plan to start with 15/51 when my 7xl/9920 eventually shows up.also on 14 cells.:D