Thanks askman

I'm still a complete newbie to electric power and all the information I'm getting from everyone is overwhelming to say the least. It's a huge learning curve for me and I have discovered that electric power is not as simple and str8 forward as advertised. All this being said, I have made a decision to give it a try and want to get the best possible "affordable" setup for my Corona.
OK so I got the VERY BASIC "kmowlege" on brushless motors and controllers, however still have one area where I know nothing at all...WHAT are the "PINIONS" what do I look out for ?

Thanks in advance
Steve