When I first started thinking about this, I knew one of the keys to success would be a favorable elevation profile. I know there's plenty of people out there who could do this in the Rockies, but I'm not one.
I knew I wanted to leave from Auburn, not drive somewhere else to start. I've always enjoyed leaving on bike tours from my own driveway. So a decent amount of climbing in the beginning has been expected no matter what. Here in east Alabama, if I were doing a big loop century with Auburn in the center, I'd expect to have an average of about 40-50 feet of climbing per mile, so roughly 4,000 to 5,000 feet for the century. That's not a horrible amount for a single century. It's not easy -- it's a challenge -- but not horrible. Two or three of those in a row, though, can wipe out anyone not thoroughly prepared.
So I very quickly started thinking I've got to head toward Florida. I've successfully ridden from Auburn to Gulf Shores on two out of three attempts in the past, and I know it starts to flatten out in south Alabama. And I've heard that most all of Florida is flat as a pancake.
I spent a good bit of time pondering routes.
The first plan I developed had me going east across Georgia on State Bicycle Route 40 which runs 270 miles from Columbus to Savannah, then turned south to ride down the East Coast Greenway, which is a 3,000 mile bike friendly route from the Canadian border to Key West, about 30% of which is off-road on dedicated multi-use paths. Yeah, Key West automatically seemed like the perfect destination.
The entire Auburn to Key West route on that first draft had me camping 5 nights, and staying in hotels the other nights. One of the camping nights would have been stealth, or just finding a spot in the woods or preferably behind a firehouse or police station or town park or similar.
The reason I finally ditched that first draft is because of what I knew would be one of the other keys to success: riding with as little weight as possible. Between my body, bike and gear weights, I'm basically trying to drop 70 lbs compared to one of the fully loaded 4-pannier bike/camping trips I've done in the past on my Surly Long Haul Trucker. I figure even the most scaled down camping set-up would be about 6 lbs and take up an area of about 16"x11"x4"
2 lbs 12 oz 4" x 16.5" Copper Spur UL1 tent
1 lb 9 oz 4" x 8.5" Air Core Ultra pad
1 lb 5" x 12" Kings Canyon UL Quilt
8.5 oz 3" x 7.5" Sleeping Giant pillow
Not bad if you're on a trip where camping is almost always required, but in this case I decided if there's an option available for saving that weight and space, I'm taking it. I feel like I'll need every advantage I can get if I'm gonna make it.
IMO, half the fun of planning a bike tour is spending the long hours studying maps. I decided I needed to figure a route that'd put me at a hotel everyday after 95 to 105 miles. On the low end, it's no problem to ride around town to make it up to 100. There's dinner to be had and supplies to be acquired... maybe a laundrymat to visit. On the high end, a stretch to 105 is doable, but I don't want to have to stretch to 120.
I tried lots of angles across Georgia to various points on the east coast and couldn't get anything to work. What finally worked was avoiding Georgia altogether.
My final route goes south through Alabama into Florida, curves around Lake Seminole and heads east across the panhandle just above Tallahassee to Jacksonville and the East Coast Greenway, then south along the Atlantic coast to the Keys. Total from Auburn to Key West will be approximately 1,017 miles and 14,500 feet of elevation.