i had a 13f and 40r it was fine but wanted a litlle more top end. so i went 1 down in the back. did i just mess up the gearing all together.... havent rode the quad yet ..

well someone can correct me if im wrong here but that basically puts you back at a stock gearing just with smaller sprockets.how i came to that is stock is 14/40 you're now running a 13/39 you basically lose the torque that you get from adding the 13 tooth with a 13/40 set up and cancel it out by dropping the tooth in the rear.near as i can tell you might as well have stock sprockets on there

That is what I run. ^^^Raven is basically right. It will give a little more top end in the ultimate end of things.

I have tried a lot of combos on this subject. 13/39 is what I stuck with, this combo helps your front end stay down, you won't wheelie as easy out of the hole. Which is what I wanted. You can still wheelie, its just not as easy.

BTW I run 20 inch Maxxis Razr II. That makes a diff too.

You need to ask yourself, What matches your riding style?

Here is a common link for knowing your speeds with diff combos.
Sprocet Calculator

Incorrect. The ratio is 3:1. A change of 3 in the rear is the same as 1 in the front.

NJC is right. Its still lower then stock. Also running smaller sprockets shaves weight and can allow the use of a shorter chain which reduces rotating weight and has an affect on performance.

i just put on 13/38 and i hate lol i like speed and with my motor i dont really need any more power i just got the rear sprocket on sale lol so i thought the front would equal it out pretty close but i can still tell so im gonna try 14/38

i drag race and i use 15f 37r with 22x11x8 pro wedge 2 and it pulls hard, im not sure wat kind of riding u do but this is my combo