We rode the Denali Highway over three days in a continuous downpour. After we were off of it, the road washed out at the western end and was closed for about a week. Having said this, keep in mind that big Pincess Cruises tour buses regularly use the Denali Highway to shuttle tourists between the Princess hotels at Copper River and Denali Park - even in the rain.
OK. I wouldn't take a road bike, but anything else with 32mm tires or fatter will make it. Some tread on the tires is necessary as there are some steep grades where you'll spin out otherwise. Plus, turning on gravel with smooth tires is treacherous. But hey, if you get to a particularly sketchy part of the road you can always walk your bike. You'll be fine. Have fun.
Since hunting is allowed off the roads in Alaska, there is a good chance that you won't see much big game - except for moose, because they are rather stupid. Of course, all the animals will see you.
Regardless, the scenery is breathtaking and you'll see the whole panopoly of Alaska fauna anyway at Denali Park. If you ride your bike into the park to camp (after the ACA tour) you will probably see major animals around every bend in the road.
The latest Adventure Cyclist Magazine has an article written by a guy who was chased by a wolf. We met that guy when we were on the North Star and we later saw an article in the Fairbanks paper about it. That's a little scary, but what's worse are those encounters that nobody knows about, where the animal breaks off the attack before the cyclist is aware that he/she was briefly on the menu.
I don't want to over emphasize the danger from animals. It exists, but you can minimize unwanted encounters by riding in groups. It's sort of like open ocean swimming. There sharks in the water with you, but the chances of being attacked are vanishingly small.
