There are a variety of bike storage bag options from standard top tube bags to full on frame bags that fill the entire triangular region to make it easier to carry gear on a bike. One of the often overlooked areas is the area in front of the seatpost on the top tube. Tailfin’s Rear Top Tube Bag is a lightweight bag that was specifically designed to wedge into that spot for both road and mountain bikes. Tailfin offers two versions of the bag: a 0.8L designed for mountain bikes and a slightly larger 0.9L version for road and gravel bikes. Both versions have the same $80 retail price and are fully waterproof with a removable internal structure to ensure the bags retain their shape. The bags use Tailfin’s V-Mount system which combines non-slip rubber pads with TPU straps for a secure and scratch-free attachment design.
The Tailfin Rear Top Tube is a high quality waterproof bag is a clever and compact way to carry more gear on your bike.
| Retail Price | $80 |
| Rating | 9.3 / 10 |
| Measured Weight (in g) | 118 |
| Likes | + Clever concept with Taillfin’s secure V-mount system + Premium build quality and materials that are designed for any weather + Bright interior makes it easy to find things |
| Dislikes | – Can get in the way while getting on or off the bike |
| Where to Buy (US) | Tailfin |
UNBOXING
The Tailfin Rear Top Tube bag comes in a compostable bag with three TPU straps tucked inside of the bag itself.
MOUNTING
As far as mounting, the Tailfin Rear Top Tube bag has Tailfin’s patented V-mount system which combines rubber pads with strap pass-throughs. The bottom of the bag has raised rubber covered mounts with three slots for straps with an additional two fabric cut outs on the right side to attach to seatposts. Unlike most bags which have hard plastic or fabric contact points that can scratch frames, Tailfin has designed the V-mount to be secure and non-damaging. The V-mount system is essentially a raised rubber base with a subtle v-shaped cutout to help it sit on curved top tubes.
There are three TPU straps included with the bag, two longer straps and one shorter one, that can be used on the bottom and optionally on the rear to attach the bag to a top tube and seat post. Even the straps are high quality TPU with a wrap-around design to allow you to cinch it down tightly instead of conventional Velcro straps. The straps can be slid through the five available slots and wrapped around plastic loops at the end. Tailfin has designed the slots to be large enough to let you pull any extra strap back through it for a clean installation.
FIT & FINISH
Visually, the Tailfin Rear Top Tube Bag has a compact triangular profile that was carefully designed to wedge against the seatpost. Tailfin offers two variations of the bag: a 0.8L mountain bike version and a 0.9L road / gravel version. The main difference between the bags is the top angle which is more shallow, which results in a smaller capacity for mountain bikes to accommodate shorter seatposts. Both bags have the same retail price and are only offered in this black finish with reflective Tailfin logo on each side. We have the road / gravel version which is fairly compact at only 139 x 185 x 45 mm or 5.5 x 7.3 x 1.8 inches.
The exterior of the bag has an interesting multi-textured design with a grid like finish on the lower part and satin finish along the top. It’s a fully waterproof bag which is why the bag has a rubberized feel to it. One of the unusual features of the bag is the fact that the zipper opens from the bottom instead of the top. This was an intentional design feature as a top zipper location can be difficult to access as the saddle can obscure it. To solve the issue of water intrusion with this bottom zipper location, Tailfin has a patented water gutter system. It’s a clever design that combines this U shaped protrusion to trap water and drain it downward through a built in pass through and out the black circular cutout.
On the interior of the bag you have a bright white and blue liner with gray side walls that make it easier to find things. It’s one large compartment with no pockets or hooks which makes sense given the small capacity. Tailfin also calls the foam inner liner a shock absorber as it’s a fairly thick foam piece that helps reduce vibrations which can scratch or damage items in the bag over time. To help the bag hold its shape there are carbon rods that run through each side. The rods can even be removed which would give the bag more flexibility to expand side-to-side.
ON THE ROAD
Having recently reviewed the Tailfin Top Tube Bag, we were excited to see how the rear version would compare. It’s clear both bags share a lot of materials and design details with the same multi-textured design and waterproof construction. You can even run both bags at the same time for even more storage and still leave a center of the top tube open if you have a larger frame like our Triban RC 520. The bag itself has enough capacity to hold a multitool, tire levers, spare tubes and even a small electric tire inflator. With it’s rectangular profile you can’t fit longer tools as you can with a top tube bag, but there is enough space for the essentials. The rearward placement of the bag isn’t as convenient for grabbing snacks while riding though, so we mostly use the bag as a substitute for a saddlebag.
Where the Tailfin really shines is with the details like the high quality materials, rigid structure and bright interior. Together the small improvements make the bag feel premium and a lot easier to use day-to-day. We’re also big fans of the V-mount system which has a nice non-slip and non-scratching rubber base with TPU straps that you can really pull tight. That eliminates the typical side-to-side play most bags have even if you only attach the bag with the bottom two straps as we did. The only downside to this bag setup is that it can get in the way of mounting and dismounting if you are not careful. We found ourselves slightly pushing it while mounting if we were not paying attention but it’s still works well and didn’t get in the way with our larger frameset when riding.
THE VERDICT
Overall, we found the Tailfin Rear Top Tube bag to be a clever concept and well executed. Tailfin has taken the classic top tube bag design and translated it to a triangular shaped bag that tucks against the seatpost. It’s a nice way to utilize otherwise unused space without getting in the way of water bottles or interfering with your pedal stroke. We were impressed with the high quality materials and build quality which give the bag a premium look and make it fully waterproof. Tailfin’s V-Mount system is also one of the best mounting systems we used that utilizes non-slip rubber pads and TPU straps that doesn’t scratch paint or sway like traditional velcro setups. The only downside of this bag is that it can get slightly in the way of mounting and dismounting. That said, the Tailfin Rear Top Tube bag is a great way to carry more gear on your bike or as a substitute for a saddlebag.
Disclaimer: The product for this review was provided by Tailfin. The views expressed on this website are solely those of the authors and are here to help people make an informed choice before a purchase. The authors or the blog itself does not get any monetary compensation from the product manufacturer or third-party websites/vendor links that are posted here.