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Tailfin Frame Bag Comes in 9 Different Sizes w/ Size-Specific Internal Carbon Space Frame!

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Tailfin has just unveiled a new line of frame bags, and they appear to have been worth the wait. Stating that they have been designing the bags over the past three years, in typical Tailfin fashion the bags had to be perfectly engineered. That meant figuring out a way to fit a huge variety of frame shapes and sizes – no easy task.

While some brands offer a few frame bag sizes to fit different bikes, inevitably there are still many bikes that they just don’t fit. Tailfin quickly realized that the answer would take more than two or three different sizes, so they ended up crowdsourcing fit information from their customers. Over five hundred riders sent Tailfin photos of their setups with measurement data, which Tailfin then used to feed a custom software program that turned the data into a range of heat maps. These heat maps were the starting point for their sizing approach which led to Tailfin settling on nine different bag shapes – 6 half-frame and 3 wedge-shaped. Between the nine sizes, Tailfin found that most riders on XS-XXL frames could find at least one bag that would fit perfectly.

Which bag size to get? There’s a (web) app for that

But how do you know just which one of those 9 frame bags will fit your bike? That’s where Tailfin’s new Frame Bag Sizing Tool comes in, and it’s super cool. Utilizing machine learning, you can upload a photo of your bike with the bottles and cages you plan to use to their website. Then the tool allows you to perfectly scale your bike and drag and drop the various bags onto the frame virtually to see which one will fit. All you need to do is make sure the photo is taken from the right distance and angle, and the software does the rest.

Tailfin could have stopped there, but as usual, the actual design of the bag goes even further into the nerdy engineering realm. After performing a case study on the most typical issues riders have with frame bags, Tailfin compiled the following list:

  • Production frame bags often with only a few size options can be a poor fit; most people don’t want to wait (or pay) for custom.
  • Most frame packs don’t have a great deal of structure, so easily balloon and cause knee rub.
  • The lack of structure in packs causes pinch points with the zip that leads to it bursting.
  • Most are attached with velcro, which can either wear bib shorts, skin or cause frame damage.
  • Most zips either require a bulky (knee-rubbing) rain flap or are not waterproof.
  • ‘Map pockets’ cannot take bulkier items like pumps
  • Frame bags and top tube bags usually require separate straps or clash, looking for a very untidy aesthetic
  • Many frame bags require mounting on three sides of the pack, which again limits sizing
  • If a frame pack isn’t well supported, it can require two hands to open and close the zip, limiting use while riding.
  • Often, there is a lack of organization inside.

Bag Structure & Design

We’ve already covered the sizing aspect, but the structure, attachment, and organization aspects are worth digging into. It’s important to note that for this round of bags, Tailfin has focused on bikes with narrower q-factor like road and gravel. To us, that sounds like they’re planning on releasing more MTB-focused bags in the future.

To prevent the bags from bulging out and rubbing on your legs as you pedal, they feature a semi-rigid carbon space frame with side struts. Instead of using a single carbon frame structure on all the bags, Tailfin realized they needed to be size-specific to ensure that all of the bags were as easy to open, and provided the same level of support. These carbon strips are also user-removable in case you want to just over-stuff your bag and not worry about it bulging out.

Like their top tube bag range, the frame bags are 3D-shaped with a tapered design both horizontally and vertically which also helps to prevent interference while pedaling. The outer shell of the bag uses their high-frequency welded construction with Hypalon and Ripstop Nylon for a lightweight, durable, and waterproof bag.

Waterproofing is then ensured through the use of a custom-sourced waterproof zipper that “holds the teeth under tension while shut, creating the maximum amount of waterproofing with less chance of the teeth being exposed when under load.” The zippers are also size-specific with a Number 6 used on the smallest bag, to a Number 10 on the largest. The zipper also uses a silent zipper pull design which will be rolled out onto the next batch of Zipped Top Tube Bags.

Inside the bag, you’ll find improved pack organization including an internal stretch mesh divider and zippered valuables pocket. There’s also a map pocket on the left side of the bag which takes advantage of the internal mesh divider to allow you to fit larger items in it like a pump. Or you can mount the pump to the internal carrier under the top tube. You’ll also find a hydration hose-compatible port up front which can be used for hydration hose or wires to keep your gadgets charged with a battery pack in the bag.

Updated V-Mount System

Tailfin frame bag on bike

Attaching the bag to the frame was also scrutinized and Tailfin is using the latest generation of their V-Mount attachment system. Instead of velcro straps that can damage your shorts and frame finish, the Tailfin system uses dedicated TPU straps with their rigid V-Mounts that keeps the bag solidly in place without damaging the frame finish.

Tailfin 3.0L half frame bag on bike

The positioning of the V-Mounts on the bags is also meant to mesh with the positioning of the mounts for their Top Tube bags so you can use the same strap for both bags.

Tailfin Frame Bag: Need to Know

Tailfin frame bag all sizes
  • Nine sizes of Half- and Wedge-style frame bags. Allowing you to prioritize water or storage.
  • Volumes from 1.9L – 6.5 Litre. Suiting bike sizes from 47-61 cm. 
  • Conformable panels adapt to bike frame geometry.
  • Internal carbon space frame design maintains structure and stops sag.
  • Carbon side struts support zip performance and reduce bulging, minimizing knee rub.
  • 3D tapered shaping designed to prevent knee rub.
  • Size-specific zips and tuned carbon struts provide all bag sizes with the same ease of use and accessibility. 
  • Proven V-Mounts provide stable attachment and minimize frame damage. 
  • Left side access ‘map’ pocket features a stretch mesh divider to allow expansion into the bag to accommodate larger, bulky items.
  • Internal organization pockets to keep valuables safe and accessible.
  • Welded Hypalon and Ripstop Nylon construction plus waterproof zips guarantee weatherproofing.
  • User-replaceable hardware.
  • Hydration hose/cable port situated at the front of the bag.
  • Price: £95/$120/110€ – £125/$160/150€ (size dependent) 


Color: Tailfin Black

Volume: 1.9L – 6.5L

Materials: Hypalon/Ripstop Nylon, Carbon Fibre

Weights: 170g (1.9L Wedge) – 334g (6.5L Half)

Pricing: £95/$120/110€ – £125/$160/€150


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Don't Take My Jobs
Don't Take My Jobs
1 month ago

Machine learning. I’m out.

1 month ago

Machine learning has been around for decades. Decades. I don’t think you necessarily understand machine learning.

1 month ago
Reply to  Robin

i don’t think you read their name

1 month ago

This looks awesome – of course this comes out the day that I recieved my (non-returnable) packs from another brand!

Michael Wayne Cleveland
Michael Wayne Cleveland
1 month ago

Quality handmade bags don’t explode, as stated, if they don’t have stiffeners. If they’re properly made, with quality materials, they… in my experience, will last at least as long, if not longer than welded bags. I have bags I made in 2011 that still work quite well.

The waterproof argument doesn’t wash with me either. If you pack your bags properly… meaning, sorting your various items in lightweight dry bags (ala almost every backpacker out in the wider world), you’ll rarely have any issues. Sadly, most of the world has been led to believe that their entire trip will be ruined if they don’t have welded bags…. Something that is very untrue…. I could go on….

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