Road/Mountain Bike Update:
The Devils Backbone Mountain Cross Bike Ride (road/gravel for 63 or 35 miles) and Blue Ridge Metric Bike Ride (road for 63 or 45 miles) are on the same weekend as the meet up. The Mountain Cross takes place on 29 Apr while the Blue Ridge Metric takes place on 30 Apr. Both start/finish near Devils Backbone and offer classic Virginia riding (with some epic climbs).
Speaking of epic climbs, Devils Backbone is also the start of the early May Wintergreen Ascent Time Trial. This road ride is 6.2 miles with 2520 ft of climbing at an average gradient of 8%. Depending on who you ask, its either a Cat 1 or HC climb. Coming back down is also fun. Check STRAVA segment 683356 for details.
For mountain bikers there is a 3.1 mile mostly single track loop on site. As noted by fw500a above, additional single track is available at Sherando Lake (aka Big Levels). There is an entrance fee if you start riding from inside the park. That said, the vast majority of trails are easily accessed off the mostly gravel Coal Rd without a fee. Map: