Dates are soft; a few days on either side of Solstice is the window.
Depart from the entrance of Denali National Park on bus with bikes & gear. Travel park road to Wonder Lake (100 miles); disembark vehicle and begin return trip on bikes. Depending on collaborative planning, most of the ride will be overnight under midnight sun when there's no traffic on road. Solstice daylight assures no darkness. Overall time on the road (including rest stops and side trips): 12-24 hours. Need more information? Let's talk.