The longish rectangular shape of the bag requires recoiling the spare tube for better fit. I use the Continental Race Light tube as a spare so it takes up less space. Also comfortably fits a tire lever, 16g gas cannister, CO2 inflator, tube patches and a small multi tool. The zip is tight i assume for the water resistance. Its also not possible to unzip the bag whilst attached to the saddle as the strap attachment overlaps the zipline. As per description, this saddle bag is made to hold spares and tucked away.
This is the ideal minimalist saddle bag. I have 1 700c tube w/80mm valve, two 16g CO2's, CO2 valve head, tire level, 6mm key for thru axle wheel removal and small baggie with extra valve core etc. I'd typically perfer not to have a saddle bag at all but this fill the void nicely. Snugs up very tight under the saddle with zero leg rub and zero movement of the bag while riding (we've all been behind "that guy" with the bag swinging back and forth). It's essentially invisible while looking down or in drops. A must have for roadie who isn't looking for a piece of luggage hanging off their seat. Yeah its small, as it should be. Must buy. Typical great service and delivery from BTD.
Once you go tubeless on a road bike, as in not carrying a spare tube anymore, your old saddle bag is suddenly obsolete and oversized. This bag is perfect for the essentials. I have a CO2 inflator and two 16g cartridges, two tire levers, a minimal multitool, and two variations of tubeless darts, all nicely arranged in this little bag. It sits quietly and is easy to clean. The only downside I've noted is that the velcro on the strap wants to split. I've glued it back down for now, but at this price, I should probably just order a couple more bags and plan on a year each.
Bought on sale for about $18 from BTD, incredible bargain especially if you compare it to the almost identical Rapha small under saddle bag that goes for $65.
Mine is loaded with
-Silca T-Ratchet & Ti Torque kit and bits (with homemade sleeve of light fabric and bits in a plastic holder)
-one Park TL-4.2 lever
-two 16g CO2 cartridges
-one Continental Race Light tube 700-1825c 80mm presta (folded up tight)
-PDW Tiny Object CO2 inflator (in a small ziplock bag)
-one pack of Park glueless patches
-one adhesive tire boot
-one presta valve core removal tool and spare presta valve core (in a small ziplock bag)
Even with all of the above, it's not over packed and it zips up easily. Though I could probably squeeze in some emergency cash or change, but that's about all it could fit in addition.
The Undersaddle Mini Saddle Bag is light, adequately water proof, and just big enough for the essentials a wide road tube, a CO2inflator, some tire levers, and an emergency $5 bill. The size is small enough the bag completely sits underneath and within either side of saddle. I recommend this bag to anyone who wants a reasonably priced, minimalist saddle bag.
I hate big, clunky saddle bags......However, there are a few items that every a avid cyclist should carry. Tube, inflato, co2, lever, etc. This bag is made well, looks good on the bike, and simply works.....
Light, waterproof and almost invisible under the saddle. Holds one tube, two CO2 cartridges, two tire irons, CO2 pump head and a small wrench. All that is needed for most rides. It sure beats most other larger, heaver bags.