I never biked it but hiked from Incline Village to Marlette Lake with my wife a couple of times so I can only tell you about this part which is probably the most spectacular. No climb here, it's mainly flat until the last couple of miles all downhill (I assume you are traveling north to south). You will have to walk the bike at a couple tricky spots (there will be markers asking you to do so) as the trail becomes very narrow with a steep drop to the side. I have seen wild teens biking it but why take a chance when there's nothing stopping you from sliding down the cliff.
You don't want to hurry anyway as the sight is really sublime. Take a sandwich with you and have a break at the bench above Sand Harbor... and take your love one with you.
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