Bike Recommendations:
Before we say anything about recommendations, understand that these are just that; recommendations. If you have a bike you are comfortable on and can do many miles on, then use that.
That being said, we do recommend your bike to have a few features that will make the ride a lot easier:
Tall gearing (like what you would find on a typical road bike). There will be many long, flat stretches of road and times when we may form a paceline, so having gearing where you aren’t spinning out at 20 mph is going to be very helpful.
Wide road tires. We would recommend tires between 30mm and 40mm wide with decent puncture protection to balance speed, durability, and comfort.
Something comfortable. Make sure that whatever bike you take is one that you have put many miles on and have the fit dialed. By day three or four of riding 100 miles each day, your body will thank you for being slightly more comfortable than aggressive.
Capable of holding gear. Your bike and wheelset should be rated for the combined weight of yourself and your gear.