Our paths crossed today, but our timing was off. Westford Hill Rd. (your mile 18) was on our driving route to the trailhead for today's hike. Would have been a major surprise to spot you and the red bike so far south.
Hardly remember Westford Hill Road, though I think it was actually one of the flatter sections?
So you were doing the fourth quarter of the Nipmuck Marathon (at least as the route went a decade or two ago)? Pretty energetic.
I did notice a few FDF's on my last mountain bike ride. Went and bought a new can of Tanglefoot (or maybe Tangle-Trap?). Curious to see how effective bright blue duct tape is when affixed to the top/back of my bright orange helmet. Should be irresistible.