i have a vp-free and its got a double chainring up front. they are 22 and 32 teeth. im using the bike for AM, Freeride,and downhill. i want to put two bigger rings up on the front but im a little confused, if i go too small i wont be able to go fast enough for my dh and freeriding, but too high and i will not be able to climb very well. i do some XC racing and im a decent climber and can use a fairly high ring but i dont want to go to high. i was thinking like a 30-38 or something. any advice.?