Gearing help

[dayxwalker]

I am just getting back into RC after 14 years out and have got myself a B4 which I will be racing indoors without much carpet ! Slippy ! Anyway I have got myself a fast servo and a 4500 lipo and a gtb and a nosram 4 star (which is about a 4.5) and a novak 7.5r. I have been told the following for gearing

4.5 using a 81t spur I need a 22t pinion ?

7.5r ?????? Can anyone help me on this ?

Is there a table for the b4 as a guide ? How do you work the gearing out ?

[Southwell]

I used to use 23/84 on a 6.5l

7.5 id say around 25/81.

[dayxwalker]

Thanks for the reply !