I'm somewhat of a beginner on skis. I have a pair of waxless backcountry skis, Rossignol BC 70's with a profile of 70/60/65 and length of 189 (the longest made). I can't seem to get any glide at all in fresh, unbroken powder, but I can when going back and skiing in my own tracks. This is with a fresh coat of glide wax. They're really not much more efficient than snowshoes in powder.
Will wider skis enable me to kick and glide? Should I look at skis 90mm or 120mm? Will they require more effort to kick and glide on existing track or to keep straight?

