For this topic I sought an expert's opinion. Jerry Dusterhoff, an avid cyclist who has written books and blog articles about his numerous bicycle trips, was more than willing to offer his expertise on this topic. In April of 2010 Jerry and several of his cycling friends biked the Trace (Follow this link to view pictures of their trip.).
90% of the information below is based on his recommendations. For more information about Jerry and his cycling books including Gotta Go! Cycling Vacations in Fantastic Locations (which includes his Natchez Trace trip), please see: Acyclist Publishing
First Question: Will the trip be self-supported or will there be vehicle support?
Determine if the bike trip is to be self-supported or will there be a sag wagon or vehicle support of some sort either during the day or at the end of the day. Naturally, a self-supported tour requires more tools and redundancy.
Bicycle:
Next, evaluate the bicycle. The bike should have new, or fairly new, tires and tubes. Jerry recommends Tire-Tuffy, an insert between the tire and tube to help prevent flats. A hard rubber tire is preferred, like Continental, as opposed to a softer compound. The chain should be in good condition. Your bike shop has a tool to measure if it has been stretched and in need of replacement.
Lubricate all metal-on-metal parts like the chain, brakes, and derailleurs. Check the cables for wear. The wheels should be trued and roll freely. Jerry is amazed at the number of riders who never lubricate the hubs
With vehicle support, in the saddle pack you should carry two tubes, tube repair kit, tire tool, boot (a 2 inch section of old tire), compressed air cylinder and nozzle, chain tool and spare quick-release link. The chain tool would only come into play if a link broke and a pin had to be forced out. Jerry's Camelbak* pack contains a tire pump, first aid kit, wet wipes and several feet of duct tape.
In the vehicle, carry a spare tire, a new chain, lubrication, a couple of spokes and a spoke wrench, and a floor pump.
If self-supported, except for the floor pump, you carry all of the above with you, securing the spokes to one of the bike tubes.
Truthfully, the Natchez Trace Parkway is very smooth and remarkably free of road trash (gravel, glass, nails). Riders should anticipate no repairs as long as they keep the tires properly inflated and the chain lubed once or twice.
Bonus information! Jerry recently wrote a blog article about how to change a flat tire. See: Changing Flats
Food and Water:
Always have two energy bars (Jerry prefers Clif), and two gels for emergencies. If traveling with a sag wagon, that is sufficient supply. If self-supported, double the energy bars.
For information about markets and restaurants near the Trace take a printed copy of our "Water and Markets" list that tells you where to exit (milepost and highway) and which direction to go and how far away the market is located. Most of the markets offer food for lunch (sandwiches, pizza, hot plate lunch, etc.) and we have also noted on the list restaurants and diners that are less than 2 miles from the Trace exit.
The park service maintains a restroom facility with drinking water at roughly 20-25 mile intervals (these are noted on the Water and Markets list and the parkway map). Always carry enough water for the whole day. The Camelbak has a 100 oz bladder, although on most days only half is consumed.
Clothing and Personal Items:
The Camelbak also carries rain gear (jacket, pants, helmet cover) whenever there is any chance of rain. If self-supported that would be all the time. Jerry also brings a wind jacket (which doubles as a sun screening garment). If self-supported, two kits are sufficient. Wash them every night and use one of those car-washing towels (the kind that absorbs water) to wring out the water. Socks are small, change every day.
Always carry sun screen and insect repellant and of course, never leave without eye-protection (sun glasses) of some sort.
* Camelbak - Jerry recommends the HAWG (Holds Alot of Water and Gear) model.
Maps, Phone Numbers and Important Information:
The official Natchez Trace Parkway map is excellent. The map folds up into a convenient 8.5" x 4" format. You can download the map or have one mailed to you by going to Natchez Trace Parkway maps.
You should have the park service's emergency phone number with you 800.300.7275. Park rangers can be very helpful.