Siltcoos Lake loop trail (fee area), south of Florence, Oregon is neat but short (4.3 mi./ mt. bike) trail. There are a lot of wild mushrooms to see in the fall on the trail. DON'T DRINK THE WATER IN SILTCOOS LAKE! Wm. Sullivan's book (mentioned in "Blacklock Point") has a good description. It's a hiking book but the bicycle ride is the same.
Ditto the neat and short for Eel Lake (6 mi/ out-and-back), also technically a hiking trail. Just yield to hikers. The hopeful plan is for the trail to eventually circle the entire lake, situated in Tugman State Park, near Reedsport.
I recommend both of these for 1 day, with a 25 mile drive on scenic Rt. 101 between.
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