In terms of touring gear, bags are probably the biggest decision to make. We want our precious cargo securely attached to our bike, while protected from the elements. Since there are so many styles of bags to choose from, I'll organize them into two general categories; rack mounted, and frame mounted.
Rack-mounted bags - panniers - are the classic means for carrying gear. Been around for decades, produced by dozens of well-established companies, and come in a wide price range. These bags are mounted to metal racks - typically aluminum or steel - and these racks are fastened to the bike frame. Look at Making Room for Gear - Pannier Space Design details information on different types of panniers.
Typically, rear panniers (or simply, Large) will hold anywhere from 20 to a whopping 80 liters of gear. Front, or small, panniers range from 10 to 20 liters. Take a look at Gear Advice for an idea of types of touring, how much gear can fit into a pannier or pack, and different styles of racks.
** Good Panniers for your tour:
Arkel Orca, Dolphin, and GT/T/XM series of panniers. I've used the Orca and XM series of bags on numerous tours and have been very happy with their performance. I also use their large Handlebar bag for my tours because of their solid mounting system (although not for carbon handlebars). You can purchase them on Arkel's website, or retailers such as Modern Bike and Universal Cycles.
Ortlieb Waterproof panniers, which many cyclists feel are the gold standard for touring bags. I've used the Back-Roller Classic, Sport-Roller Classic (which had been called Front-Roller in the past), and Bike-Packer bags, and they're great. You can get them at Ortlieb's site (they have a section for US customers), or from many, many, retailers. I've bought gear from REI, Backcountry, Modern Bike, Campsaver, and BikeTiresDirect.com.
Axiom Panniers produce some lower-cost bags, including waterproof models. Check out their website, Axiom Gear, or retails like REI, Modern Bike, and even Amazon.
Frame-mounted bags - which the industry typically refers to as "packs" - have exploded recently, primarily from the bikepacking sector. These packs are secured directly to the bike frame using a variety of straps. Make sure to check out the website Bikepacking, which includes reviews of frame-mounted bags.
Although frame-mounted bags come in many shapes and sizes, common types are:
Handlebar Roll. Basically, a dry bag with velcro straps that secure the bag to the handlebar. Before buying, check to see if your bike's brake and shifter cables will be in the way, which can be a problem with older bikes. Newer gravel/adventure/mountain/all-road/etc. bikes keep cables out of the way.
Seat Pack. So, another dry bag that secures under the seat. Check the clearance from the bottom rails of the seat to the top of the rear tire to verify the bag won't rub against the tire. Short cyclists on small frame bikes, or those that keep the seat down low, could have a problem fitting this bag. Dropper posts can be an issue as well.
Frame Bag. A bag that fits inside the "triangle" of the bike's frame. This may be the hardest to fit since there are so many different bike geometries to contend with. Fitting one in also could mean sacrificing water bottle cages.
Top Tube Bag. Also referred to as a Frame Bag, although only secures to the top tube, which means it may be easier to fit.
Fork-Mounted Bag. Bike manufacturers have responded to the bikepacking crowd and produced bikes with mounts on the front fork. These small bags, about the size of a large water bottle, take advantage of these mounts to provide a bit more space for gear (typically around 4 liters).
Feedbag/Stem Mounted Bag. A, ahem, grab bag of other designs that are secured to the top tube and stem.
** Good frame bags for your tour:
Revelate Designs. One of the first companies dedicated to Bikepacking, they produce a solid lineup of frame-mounted bags. I've used the Sweetroll (handlebar pack), and Terrapin System (seat pack), in addition to their older seat packs, the Viscacha and Pika.
Ortlieb. Not surprising that a company leading traditional touring panniers should also venture into bikepacking gear. Featuring their well-traveled roll-up type waterproof design, the Seat-Pack, and Handlebar Pack are built to handle all types of weather. Look for the same retailers mentioned above.
Of course nothing says you can't pick and choose from both categories. On a recent ride, I ran into someone on a three-day, no camping, ride using front panniers (rack mounted) and a rear seat pack (frame mounted).
Here are some pros and cons to consider when choosing bags:
Large capacity, ranging from 10 liters to 70 liters.
Mounting systems that keep bags attached, yet also allow easy removal.
Many inexpensive options are available.
Depending on the rack system, these bags can be secured low to the ground to improve ride stability.
Has a low price per volume of storage.
Require racks mounted to the bike frame. See The Skinny on Racks for more information.
May not stay attached on rough terrain, such as gravel trails.
Large capacity. May encourage you to carry too much gear.
No racks are required, which is a nice price savings.
Built to stay securely mounted over rough terrain.
Kept inline with the bike's geometry - they don't stick out like panniers (good in tight spaces).
Smaller capacity. A large seat pack typically holds around 17 liters; a large handlebar pack 18 liters.
High price per volume of storage.
Very dependent on frame design. Unique frames may require custom packs.
The location of cables, and the amount of tire clearance, can be an issue.
Check out these websites for reviews and recommendations:
The 6 Best Bike Panniers of 2023 from GearLab
REI's The Best Bags of 2023: Tested (sure - they did pick one of their own brand. Still good information to be had)
Bicycling Touring 101 has their 13 Best Waterproof Bike Panniers for Touring & Commuting in 2023
If you're only interested in frame packs, then Treeline Review has their Best Bike Frame Bags of 2023