Old Fall River Road is the original road that took you over the Continental Divide before Trail Ridge was built. It’s a one lane dirt road that climbs 5,000 ft up the side of a mountain. As cyclists we can ride this road anytime that cars are allowed, but with the condition that the road is a one way when cars are allowed. This simply means that for a majority of the year you can ride up Old Fall River and then come back to civilization on Trail Ridge.
Old Fall River Road in Rocky Mountain National Park is expected to open to vehicles this Saturday, June 23 2018, for the season. Old Fall River Road normally opens by the Fourth of July holiday weekend. This summer, during periods of high vehicle congestion, park staff may restrict vehicle access when needed on Old Fall River Road. The road will close for the season on Monday, October 1, for annual maintenance, and reopen to bicycles and pedestrians from October 6 through November 30. On December 1, the road will revert to trail status.
https://www.nps.gov/romo/learn/news/old-fall-river-road-in-rocky-mountain-national-park-expected-to-open-saturday-june-23.htm