So you want to ride Lost Lake "the whole thing".

I get enough questions about this to warrant its own page. You're an experience mt. biker. You ride 16 miles back home easily. You're in Seward and just have the one day to do it, so YOLO, you want to ride "the whole thing" and ride from Seward up to Lost Lake, then down the Primrose Trail to Kenai Lake (approximately 17 miles from Seward) or vice versa (start at Primrose campground and ride to Seward).

I'm here to tell you don't do that. Just ride Lost Lake as an out and back.

#1 Lost Lake Trail is the better ride. Better conditions, more sun, drier trail, better views etc etc. Primrose is consistently muddier and gnarlier.

#2 You are going to want to familiarize yourself with the trail on the way up. Lost Lake has hairpin turns and cliffs. On the way up, you'll say "oh I better remember to slow down around that corner because that is one huge cliff." This is valuable information.

#3 Something will happen. A mechanical, a flat, you bonk, you stop to pick berries, or a wild animal forces you to turn around. I've gotten lots frantic calls from whoever is suppose to pick up an overdue rider. You probably won't have cell reception, so you can't communicate with them. I tell them you probably rode in 5 miles and got turned around. They think you died. I'll say "Naw... they're fine. Probably." and your fiancé is not reassured. They'll say "Should I drive back into town and see if they turned around? Or should I keep waiting in case they show up?" What the hell do I say to that?!

#4 I've ridden with lots and lots of visitors. 16 miles here is not the same as 16 miles 'back home.' You mountain bike, I get it. But you probably don't have a 7 mile climb. It's an ass kicker. Alaska is not something to be conquered. You will be humbled. Be humbled safely.

My Advice:

Start at Lost Lake Trailhead near Seward. Ride in until you had enough. Ride to the High Point, ride to the lake, hell keep going if you feel good, make it a 20 mile ride, but then turn around and come back the same way. You can ride back to town. No one is waiting, no one is driving wasting gas, no one is calling me asking if you are dead. Win-win-win!