I have a Blade, and I am a newbie to Heli flying. I have been reading about the Trex also.

Now the Blade comes with a 10t motor and you can get them in 8t. Trex I believe comes in a 13t and you can get them in 11t. I either have things backwards or I am thouroghly confused.

I would think that the more teath in the engine gear the fast the rotor gear would spin. The motor speeds don't change say at 50% so the more teeth in the motor gear the more the main gear should be moving. Is this correct or am I looking at it wrong.

I read that using an 8t gear motor on the blade really helps with performance but now with my thought path I am confused as to why because it would seem to me that the main rotor blade would be spinning slower and not faster with a smaller tooth motor gear.

What Pinion you use is depended on what motor you have. Your motor has a kv rating like my AON as a kv of 3500. This means for every 1 volt I put in I’ll get 3500 rpm. This is where your gearing comes into play.

Example:
Motor AON 3500
Battery 3s
Pinion 15t
Main gear 150t
Motor Efficiency 80%

3500*11.*15/150*8=3108 this would be an approximate head speed

OK GM. Thanks for clearing that up.