I discovered on this particular Saturday morning what the best snow biking conditions are: a bit warmer and snow on the ground that has become hard packed because of the warmer weather, lots of traffic, and no fresh snow. Riding up Jardine Juniper was a blast because of this and a lot easier than it otherwise would have been.
I still didn't make it up all that far (maybe only a mile or mile and a half I think), and the last section stopped being as much fun because the trail got so narrow that every time the wheels spun out I would turn the wheel slightly and then hit the wall of snow on the side, causing me to have to stop. When you end up hitting the first sign after the trailhead by the creek crossing (shown at left and at the top) the trail isn't very well traveled anymore and consequently becomes near impossible to ride. The lower section, however, was a lot of fun and really easy, and the whole thing was extremely easy to ride down.
I passed at least two sets of cross country skiers along the way, both of which I think were a little surprised to see a biker at this time of year. It was actually after I passed the first group that the riding got a bit tougher - I think they had really helped to pack down the snow.