
Originally Posted by
m.eliza
IMO the trail is slower because you need to be careful of the other people using it.
You need to be careful of other users on the road, too. 
Average speed depends on many factors. Some of the slowest rides I've done have been on-road, because they were in urban areas with frequent intersections.
The trail in question here is 45 miles long, from Arlington, VA (just over the river from DC and heavily populated) out to Purcelleville, VA (less crowded suburbs/exurbs). Some parts are crowded with other cyclists, joggers, dog walkers, etc. while others are pretty empty.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles