I’ve got to throw my two cents in here – I have been a advanced mountain bike instructor for about four years and one of the biggest things I try to pass on to the people I teach is trail etiquette, and the first thing in trail etiquette is to keep the tires rolling. Dragging your rear wheel around switchbacks, down chutes, over drops is bad, for the trail, and for speed – locking up the tire = loss of control – loss of control = loss of speed.

A power slide is different than skidding, but still bad for the trail. A power slide is skidding the rear end with out using the rear brake. Putting your weight back and to the outside of the turn, essentially forcing the rear end to lose traction and slide, does it. Again, bad for the trail.

Drifting is completely different. To drift is to controllably break traction with both tires to set up a better position in the turn, or a better line. I use it most on bermed corners. For example, on a corner where the berm starts late, I’ll start the turn before the beginning of the berm, as I’m coming into the apex I will lean the bike over more, keeping my weight centered and on the outside pedal, this force will cause my bike to “drift” laterally up the berm and into a better line. As the tires move up the berm, the contact area the tires have with the dirt increases because the lean angle of the bike matches the higher angle of the berm, causing the tires to hook up and stop the drift. Most times drifting is done without the brakes, just the force of the turn will cause the slide, but in some situations tapping the brakes can initiate the drift.

I drift all the time when the trail conditions are loose over hard pack. It can be used in more areas than berms. The distance that the bike “slides” in a drift is insignificant when compared to a power slide or a skid. It would take a thousand "drifts" to equal one long skid. Drifting is defiantly an advanced technique, but when you learn to use it right it makes riding that much more enjoyable.