Northridge is not a trail one should necessarily do with a bike. Or do at all. It took me about 7 hours, 5 of which were spent hiking the loose, steep motocross trail. Though, I was sure glad to have my bike on the way back and the views from the top of the ridge were great. There was a bit of snow and quite a bit of mud on S. Cle Elum Ridge trail. Likewise, Manastash Ridge trail looked muddy and snowy at higher, north-facing elevation.
17 miles, 7000 ft., 7 hours. GPX track