single speed

Couldn't find anything when I searched. Pretty noob question. Does anyone use single speed for dh? If yes, why? If no, why? I have a STP1 06 and its single speed, I was going to do some dh/freeride stuff. If i forgot something, tell me.

Ok hey Guys, I am just about saved up for a New Dirt jumper/Street, Skate park type of bike. I have looked around for some good bikes and who retailers and it would be great if anybody could help me with some more info. Here are the bikes that have got my mind: 1. GT Ruckus UF 2008 Model -...