A bike saddle bag carries the essentials without a backpack. Small under-seat models, from less than a litre to a few litres, hold an inner tube, tyre levers and a tool; large bikepacking saddle bags, from 5 to 18 litres, take clothing and camping kit. Choose the capacity, then the mounting system and the level of waterproofing.
The under-seat bag slips between the rails and the seatpost, discreet and light: it is the repair kit that stays permanently on a road bike, gravel bike or mountain bike. The bikepacking saddle bag, or seat pack, extends the saddle backwards in a long cylinder attached to the rails and the post. With no rack needed, it suits carbon frames and road and gravel bikes alike, and carries the volume of a classic rear pannier for less weight.
A well-filled bag is better than a large, half-empty one that sways. Some models expand, others compress with a roll-top closure.
Hook-and-loop straps, passed around the rails and the seatpost, suit almost every saddle and add little weight. A clip or adapter system is fitted once under the saddle and lets you remove the bag in one movement, handy for keeping it with you during a stop. For large volumes, a harness or a rigid holder attached to the rails takes a removable dry bag: you slide it out of its cradle without undoing all the straps.
A loaded bikepacking saddle bag tends to sway when you ride out of the saddle. Put heavy, dense items against the saddle, tighten the compression straps and keep the rest in a frame bag, which sits more centrally. Check the space between the saddle and the rear tyre, reduced on a small frame or a full-suspension mountain bike, and the length of exposed seatpost. A dropper post greatly limits the usable travel, unless you use a holder designed for it.
A water-resistant bag withstands rain, while a waterproof bag, with welded seams and a roll-top closure, also copes with spray from the rear wheel. As it often hides the seatpost, plan for a rear light attached to the dedicated loop on the bag or to the seatstay.
At the front, handlebar bags keep the essentials within reach. For heavier loads, a pannier rack and pannier bags remain the most stable solution. All storage solutions are in bike bags and luggage.
Topeak, a Taiwanese accessories manufacturer, offers the Aero Wedge Pack with its QuickClick mount, from Micro to Large, and the BackLoader in 6, 10 or 15 litres for bikepacking.
Klickfix, which produces its adapters in Solingen, Germany, pairs its Micro bags, from 0.2 to 0.8 litres, and Max Sport bags with a clip adapter that stays under the saddle.
Zefal, headquartered in Jargeau, in the Loiret in France, makes the water-resistant Z Adventure in 5, 11 or 17 litres and the Z Light for tools.
Acepac, a Czech brand specialising in bikepacking, makes the Saddle Bag MKIII and the 8-litre Saddle Dry.
Pro, Shimano's accessories and components brand, offers the Performance from small to XL and the Discover, including a 10-litre Team Gravel version.
VAUDE, a German family business based near Tettnang, covers every format, from the Tool and Race Light bags to the 6 and 10.5-litre Trailsaddle and the 15-litre Trailsaddle Cage, mounted on a holder.
Discontinued colours and formats go through bags and luggage clearance; newly listed bags appear among new arrivals. Make the most of the seasonal sales to get ready for a first cycling trip.
The repair essentials: an inner tube or tubeless plugs, tyre levers, a CO2 cartridge or mini pump, a multi-tool with a chain tool and a quick link. Add a little cash and some ID and, in a large bag, a warm layer.
The two complement each other. The frame bag, low and central, takes heavy items; the saddle bag takes light, bulky items, such as clothing or a sleeping bag.
A small under-seat bag is, as long as it stays above the collar when the post drops. A large bikepacking saddle bag, on the other hand, blocks part of the travel, unless it is a model designed for dropper posts.
Fill it completely, load the heaviest items against the saddle, tighten the rail and seatpost straps, then compress the remaining volume. A rigid holder under the saddle gives the best stability.
For a light trip, yes, together with a frame bag and a handlebar bag. To carry a tent, a stove and clothing for several weeks, pannier bags offer more volume.