You never think about your brakes when you're pumping through foliage-covered rollers and around perfect berms, but you sure would if they suddenly stopped working. Better to snag SRAM's Guide/XO Trail Disc Brake Pad before it's too late, and let the organic or sintered stopping power take care of you. Organic pads are better for XC riding, and sintered pads serve up more stopping power for riders who like to push it on long high-speed descents.