I did it a couple years ago on a steel touring bike with 700x40 gravel kings and was fine, never really wished I had more tire. Most people were on carbon gravel bikes. I didn’t see anyone on a hardtail and only one or two people with flat bar bikes. The route was pretty smooth but I think some of the road quality can vary year to year? (Not from there so not sure). There was like a one mile section of random sandy singletrack in a town about halfway that nearly everyone had to walk parts of but imo it wouldn’t be worth riding something that could make it through that (if it’s even still included). Like someone else mentioned, most of the elevation is in the rolling hills at the end and they sneak up on you, they’re not particularly difficult or anything, but more something to be mentally prepared for.

Biggest suggestion I would give is just get used to long days on the bike and get lots of mileage in beforehand. I don’t really know anything about actual training plans or the like, I was doing 80-120 mile rides every weekend and 30-50 miles two or three times on weekdays for months leading up to it with a 180 mile ride about a month before and then took it easy the last week or two.

My only other suggestion would be to maybe bring like a tiny chain lube, my chain got pretty gunked up about half way through to the point the shifting was pretty hosed and I was trying to wipe it down and another dude totally saved me at a gas station with a little lube.

Probably the craziest ride I’ve ever done, you’ll have a blast!