In reply to Jamie Bankhead:
Jamie, unfortunately the bridge that was washed away was the one required to access the track.
Theres one higher up near Stonetroper which is clearly signed as the last bridge over the feshie. You could cross there and see what the single track is like on the east bank (I saw folk cycling this last month). Having said that though you'd be as well parking at Auchlean and cycling from there.
The mountain biking web sites have plenty of info on the routes round feshie as I'd though about seeing how far up I could get the bike there myself a few weeks ago.
The Linn of Dee approach is fine but this seems quite an adventurous alternative.