What you pack for a bike tour will depend on many factors.
Before you fill your panniers, ask yourself how long you will be gone (longer trips can require more equipment, for reasons for comfort, budgeting and self-reliance), whether or not there will be bike shops nearby and what kind of weather you’re likely to deal with.
Your packing list might include some or all of these things…
The packing list below is based on an expedition tour for a couple, going through several seasons with possibly cold rain and nighttime temperatures near freezing. It also contains some equipment which is heavy and could be seen as unnecessary but allows for more independence and comfort, helping to keep you on budget.
On The Bike
*Bottle cages and bottles (3)
*Brooks Saddle
*Bar ends
*Tubus Racks (read about Choosing Racks)
*Wide Tires (read about Tires for Bike Touring)
*Good Pedals
Bike Tools & Spares
*Allen keys to fit screws on your bike (they are easier to maneuver than a multitool in tight spots)
*Bike grease
*Chain lubricant
*Touch-up paint for scratches to the frame (you can use nail polish)
*Brake cable
*Gear cable
*Brake pads (8)
*Bungee cords (4)
*1 Cable lock
*1 D-lock
*Cone spanners for taking hubs apart
*Nuts and bolts (get replacements for all the kinds that are on your bike)
*Proofide (if you have a leather saddle)
*Puncture repair kit
*Rag for cleaning
*Replacement spokes (stored inside the seatpost)
*J.A. Stein Mini Cassette Lock (to take the cassette off when you have a broken spoke)
*Tire levers 
*Topeak multitool
*Topeak Mountain Morph pump
*Zipties (good if your rack breaks)
Panniers & Handlebar Bags
*Ortlieb (incredibly durable – waterproof and we’d say even bombproof)
*Dry Bag (for the tent)
*Cheap dollar-store heavy duty bag (great for storing all manner of extras, bungee corded onto the back)
Camping
*Camelbak Unbottle 70 water holders (2)
*Hilleberg Nallo 3GT tent (read more on Tents for Bike Touring)
*Hilleberg XP10 tarp
*Hilleberg groundsheet
*Long life supermarket bags (for shopping or as seats when camping on muddy ground)
*MSR Miniworks EX water filter & maintenance kit
*Petzl Tikka headlamps (2)
*Flip flops for shower
*Down sleeping bags rated to -10C (2) from PHD Mountain Software
*Sleepsacks (homemade from cotton) x 2
*String, 6-10 meters (for a clothesline, stringing food in trees, getting water from wells)
*Thermarest Z-rest mattress (2)
Clothes (For One Person)
*Goretex Jacket
*Goretex Rain Pants
*Waterproof Shoe Covers
*Black fleece
*Cold weather gloves
*Headband (for ears in cold weather)
*Cycling Gloves
*T-shirts (3)
*Long-sleeved base layer
*Merino wool Top
*Cycling shorts x 2
*Long cycling leggings
*Light-weight pants x 2
*Cycling Shoes
*Long Johns
*Underwear (4)
*Merino wool socks (4)
*SealSkinz waterproof socks
*Sunglasses
*Swimming trunks
The Kitchen
*Stainless steel pots (2)
*Non-stick frying pan (6″)
*Thermos
*Cooking knives (1 paring knife, 1 serrated)
*Dish soap
*Dish Towel
*Lighter
*Film canisters x 6 (for spices)
*Plates (2)
*Cups (2)
*Fork/Spoon
*MSR Whisperlite Internationale Stove & repair kit
*Fuel Bottle (650ml)
*Ortlieb foldable bowl
*Swiss Army knife (corkscrew, bottle opener)
*Wooden spoon
*Screw top bottles for oil, vinegar, honey (2)
*Scrubbing pads
Entertainment
*Books (2)
*Roberts R9968 SW radio
Other random things
*Spare keys (stored in front pocket of one pannier)
*Paper notebook
*Cod liver oil pills
*Lens cleaner for glasses, camera lenses
Personal Hygiene & Toiletries
(We’re sure we don’t need to tell you to take your toothbrush or shampoo, but also consider these things)
*Sunscreen 30 SPF
*First Aid Kit (Plasters, Antiseptic cream, Scissors, Tweezers, Emergency Blanket)
*Mooncup (for women)
*pStyle or other urinary device (for women)
*Toilet paper
*Baby wipes
*Washing powder for laundry
*Travel Towel
Technology
*Digital Camera (we had the Nikon D80)
*Wireless Bike Computer
*Edirol 09 sound recorder
*Kindle (if you don’t want to carry books)
*mp3 player
*Netbook laptop (Asus EEE is good)
*Padded bags for laptop and gadgets
*Spare AA and AAA batteries
*Mini tripod
*Cables and electric plug converters
*USB stick