I've ridden MRT every month of the year. Also seen it under snow and totally impassable as late as April. Just depends on the year. Uppermost section (near Clear Lk) is about 3000' elevation and this almost certainly won't be accessible in mid-March (although I rode all the way around Clear Lake on Feb. 21st last year, so anything's possible).A-Town212 said:
The lower trailhead near the town of McKenzie Bridge is closer to 1600' elevation. You ~might~ be able to ride up as far as Tamolich Falls (aka Blue Pool) but it's a total crap shoot.
--sParty