If you want to ride up the Nashua River Rail Trail and back, here's some info that might help. From the Ayer parking lot, it's 4 miles to Groton center, then 5 miles more to Pepperell center (where there's a good ice cream shop), then another 3 miles to the end of the rail trail at Gilson Road in Nashua where there's not much of anything. The trail ends there, but you can take roads another 3 miles to the lovely Mine Falls Park in Nashua, which has a paved trail that you can ride in a 4 mile loop (or less, if you take any cutoffs). Perfect place for a picnic.
For the ambitious among you who want to do all of that, the whole route up and back is about 35 miles, and it's mostly shaded. If you skip Mine Falls Park, from Ayer to the end of the rail trail and back is 24 miles, but I can't recommend the spot for a picnic. Those of you more focused on refreshments can go from Ayer to ice cream in Pepperell and back in 18 miles. Or for some seriously good eats, to Filho's Cucina in Groton center and back in 7.5 miles. Those of us with vehicles or physiques built more for show than performance can get from the Ayer end of the rail trail to good pizza at The Cottage in Ayer center in 0.2 mile. Personally, this year I walked 90 feet to get a couple of Chuck's chili dogs at Fresh Ayer Sports, and was mightily pleased with them.
If you decide to bring a road bike for a longer ride, bring your rats, too! What would the festival be without them?
Tim