Fat biking Knik Glacier in Alaska was awesome. The trail is around 22 miles roundtrip. Knik Glacier is located 50 miles north of Anchorage. You can access the trail by parking at Knik Glacier Tours in Palmer and hoppin on your fat bike.
The face of Knik Glacier is over 5 miles long. It's massive and impressive to see all of its glacial formations. Be prepared to cross open water and start early in the day as winter light is short.