An unknown poster set the route:
Easy one to beat! "Cadillac Doubleback" Acadia NP cadillac entrance on 233 to kebo mtn trail to north ridge trail to cadillac summit to south ridge trail to route 3 and back. approx 3000' elevation gain. approx 12 mi (I have an old garmin 305, doesn't measure distance with elevation well). Did today with icy conditions on north ridge in 2hrs 37mins.
Here's garmin connect data on the above: