Overall this is a pretty good wedge pack. I bought this because the setback post on my Domane SL6 severely limits the underseat packs I can use and this was one of the few that works. The straps do a decent job stabilizing the pack under the rails, but there is some bounce with them. The biggest beef I have with the pack is its hard to unzip the waterproofed zipper because the pack isn't quite long enough to stick out beyond the rear lip of the seat, requiring some mildly annoying fiddling to get it open - definitely not a one-handed job by any stretch. The light loop is well-placed and wide enough to accommodate most taillights. The interior mesh pocket is perfect for a multitool.
Got this size small pack for my wife's new gravel bike. I like the way this style of pack provides a vertical mounting surface for tail lights. She is short so there is little space for a pack between the saddle and the tire. I use the medium pack on my bikes but am much taller, space below the saddle is not an issue. On my wife's bike there is only 1/2" between this pack and the tire so I recommend some changes to the pack design to make it more usable for the "little" people among us. As you can see in the picture of the pack, the zipper pull hangs an inch below which results in it rubbing the tire. Have to leave it partially open to avoid this. A dual pull zipper which closes at the top would eliminate this problem. The rear adjustment straps adjust from the bottom and the excess left over when tightened hang down and rub the tire. Move the adjustment part of the strap to the top to eliminate this. For safety, I bought a Garmin radar/light to alert her of cars approaching. There is no room on her seat post to mount the radar so it has to go on the pack. The tail light mount is on the bottom so the radar would rub the tire if mounted there. Had to move the tail light mount to the top rear of the pack where the Topeak logo was to make room for the radar/tail light. Topeak, are you listening?
You've got all kinds of junk in the trunk- tubes, tire boots, tire levers, CO2 cartridges, CO2 inflator, house keys, ID... You need one of these, and you need one that isn't going to fall apart after one season. And here you are. Do it. These are tough, ripstop, and the buckles are sturdy. I put in 4-5K miles/year, and this bag shows no signs of real wear. Would purchase again.
Can fit a tube, C02, powerbar inside, a wind jacket when expanded.
Would have preferred the XL size, but this one still works with the dropper seat post all most all the way down.
Zippers feel a bit cheap and snag if there is any load, but otherwise well designed.
Even works with a Mtn bike fender on seatpost below, if seat is up high.
Overall happy, just wish zippers were beefier and size was a bit larger for an extra layer like a wind vest.
The medium size (with zipper expansion if needed) fits nicely within my 145mm saddle dimensions, is secure and well-made. Swallows a bagged 25mm tube, tire tools, multi-tool, wallet and clamshell cellphone, couple tubes of Neosporin, couple individually wrapped sterile wipes, eye drops, cut-tire patch. I've used the zipper'd expansion only once, but it came in handy. (Riding home holding an acquired item in one hand is such a drag.) Would buy again. (Would have preferred dual zippers on the back, but all the other features still add up to best I've used.)
Big enough to keep all of my flat repair stuff for off-road, including a Lezyne pump with room to spare.
One downside is that the strap that goes around the seatpost doesn't have an attachment to keep the excess strap from flapping around - it does firmly attach to the seatpost, though. Ideally it would have some Velcro or something to keep the very end snug. I just tuck it in, but it's not an ideal solution.
I trust and like Topeak products but this is not one of them. I like the size and features of the bag. It fits everything I need for my gravel bike. I like the expandable zipper. However the strap for the seat post easily wears through the stitching that attaches it to the bag and you find that the bag now sways around uncontrollably making it not very functional and a waste of money. Look elsewhere.
Needed to replace my pack that had totally worn out over the last 10 years, couldn't find the exact match for it at Planet Bike, so I tried this Topeak pack, very pleased! It has a better profile to attach to the bike and the volume was just right without the expansion feature. A single zipper instead of a dual zip like the last one, but it seems smooth, we'll see if I get the same distance out this on as I did the last one.
I have several different brands, and this is is among my favorites. Straps hold the bag firmly in place, and it has a small pocket on the opening flap. My only suggestion for improvement would be on the elastic loops underneath, I use these to hold a spare tire and the could be a little more generous in size. Better yet, have an adjustable nylon strep with a buckle for easy attachment and removal.