Is a 31 inch bat too small for the varsity level? I'm about six feet tall but only weigh 140 lbs.

I think whatever feels good to you and whatever your comfortable with is what you should use.

Some pros only use a 32.

im in the same weight/height situation you are and i use a 32

what happens when you move up to a 32? do you lose bat speed?

not really, I just feel more comfortable with the 31

like someone said above, go with what you are comfortable with. based on your height/ weight though, mlb.com says you should be using a 33...

http://shop.mlb.com/info/index.jsp?categoryId=222857&infoPath=222974

Yeah, I would also suggest going bigger than a 31. Im 5-11 and I use a 33. I just think it would be easier to cover the outside corner of the plate with a longer bat than 31. But if you are doing well and feel more comfortable with the smaller bat--stick with it.

Use whatever feels right. I would suggest that you use the bat that you feel you have the best control with. If a 32 is too heavy or doesn't feel comfortable, don't use it.