Complete Guide to Top Tube Bags

Creating the perfect Top Tube Bag

As with all our products, we aim to create the ultimate solutions. In this respect, our Top Tube Bag is no exception.

Watch Tailfin founder Nick explaining what makes the Top Tube Bag so special

With the Long and Rear Top Tube Bags now in the range, we have taken our vision of the perfect standard Top Tube Bag and taken it to new levels.

Fitting to your bike

All Tailfin Top Tube Bags can be mounted using the supplied TPU straps, plus the standard and Long versions can also be bolted on to compatible frames. The V-Mount hardware provides two bolt-on positions: the rubber boots of the V-Mount system are pre-cut to retain and allow the bolts to pass through neatly.

Using the V-Mount in this way provides market-leading stability for a bolt-on Top Tube bag. This also allows for the load to be spread away from the bike frame’s riv-nuts, minimising any potential damage when carrying heavier loads in your Top Tube bag.

The Tailfin Top Tube Bag also has removable straps; this improves bag life, something sewn-on velcro straps can’t compete with.

Curing instability – V-Mount technology

Without a doubt, the number one issue with all top tube bags is the propensity for unwanted movement. This movement can come from terrain-based vibrations or rider interaction (knocking to the side when getting on and off the bike, for example). Many existing bike bags fit well when the bike’s top tube matches the bag’s base width, but often need an additional stabilising strap around the fork steerer.

They stop working well when it’s either trying to grip narrow-diameter steel tubing or oversized carbon and alloy tubes. Luckily, we already had the basis for the solution in the form of our proven V-Mount technology (found on our existing Downtube Packs). The V-Mount system combines many parts, all working together in harmony.

From the tacky rubber pads to the abrasion-resistant and grippy TPU straps to the welded V-Mount tunnel/garage to how we transfer the rigidity to the internal HDPE ‘Taco Shell’. It’s the unification of these parts that create the magic. 

Cargo Straps

All of our Small Packs secure to your frame using our Cargo straps, and each bike bag ships with them included as standard.

The new Tailfin Cargo Strap pays homage to the ever-popular, incredibly effective ski strap system yet boosts the design to 11. We created it to deal with the demands of bikepacking specifically. But rather than just copy and paste the classic design, we invested in considerable R&D to offer specific advantages from our Load Lock Buckle design and material selection.

The buckle shaping has bicycle frame tubing profiles in mind, and the whole strap utilises non-scratching materials. The version supplied with the Downtube Packs has a unique shortened prong designed to eliminate snagging on clothing or skin and sits flush with the strap when engaged:

Protecting your frame

We spent a lot of time testing our V-Mount system when fitted with dedicated TPU straps, on our ‘wiggle rig’ (see video at the top of the page). The results speak for themselves, but if you’d rather not watch the video, the bottom line is this: when attached correctly, V-Mounts and Cargo Straps eliminate movement completely.

Waterproofing

Our entire Top Tube Bag range uses a revised, lighter version of Tailfin’s signature Hypalon/Diamond Ripstop Nylon* mix to create a highly water-resistant bag. All bags feature our 3D welded construction process (no mean feat on such a small yet complex design), eliminating any potential weak points for water to get in.

*Due to the lower wear and stresses placed on a top tube bag, we could incorporate a lighter-weight 210D Hypalon material without impacting durability.

Which bag is right for me?

Zipped versions: 0.8L, 1.1L, 1.5L

Flip Lid versions: 1.1L, 1.5L

Every rider is different. Through extensive research and body mapping, it was obvious that one of the limiting factors of a rider’s use of top tube bike bags is the tendency for the bag to interfere with knee tracking.

Slow-motion video capture and anecdotal field testing indicated that if the goal is maximising the amount of storage available, each rider and bike combination has a ‘maximum bag size’ before causing obvious knee rub. Just as with a shoe, glove or even bike frame, there is an optimum ‘sweet spot’ in terms of the shape. One size most certainly does not fit all. If the goal is maximising bag size, as a guide:

If you suffer from knee rub with other bags or have a narrow gait on the bike, then 0.8L Zip Top Tube Bag is the one for you.

If you ride mainly gravel or road bikes and don’t suffer from knee rub with other top tube bags, then go with a 1.1L (zip or flip) bike bag.

If you ride mainly mountain bikes you will want to order a 1.5L (zip or flip) bike bag.

Top Tube Bags (Flip) – what’s unique?

Our Flip Lid bags have 2 unique features:

1) a functional flip-top shape constructed using 3D welding and

2) a secure and reliable closure mechanism (Mag-Lock technology).

Mag-Lock Technology – We are firm believers that latches and mechanisms offer a better experience when they have a ‘positive action’ – just like the X-Clamps of our pannier bags. What we mean by this is we want these mechanisms to be actively opened and closed; this way, you 100% know that the operation has been done.

The Mag-Lock is designed to offer a repeatable closure, be simple to operate even with winter gloves, provide noticeable feedback to eliminate second-guessing, be self-adjusting and user repairable. This last part is of vital importance with this style of closure. We utilised shock cord to allow the cycle bag to stretch but we are well aware that even though this is the best material for the job, it has a finite life span. To counter this, rather than just attach it permanently with glue or stitches we developed a cunning little clutch mechanism that allows for easy replacement of the cord without additional bulk.

Top Tube Bags (Zip) – what’s unique?

Zips are often the weak point of a top tube bag, both from a waterproofing perspective and also as they tend to fail over time if a bag is either overstuffed or the angle and support of the zip are not enough to overcome friction introduced when opening or closing the bag. In order to ensure our zips stay reliable for the lifetime of a bag we had to incorporate the following features:

1. The internal HDPE structure of the bike bag supports the zip, allowing for easy, one-handed operation.
2. The V-Mounts hold the bag with enough stability to ensure the bag doesn’t move whilst operating the zip.
3. The top radius of the bike bag is constant to ensure even tension throughout the entire length of the zip.
4. We haven’t removed the secondary metal zip puller to save weight. We found incorporating it alongside our cord pull ensures that the zip is operated at the correct angle and the operator isn’t pulling it away from the direction of the zip.
5. Most manufacturers opt for a standard No.5 sized zip. We went oversize to reduce failures.

Introducing the Long Top Tube Bag

The range of Long Top Tube Bags from Tailfin combines everything we learnt from developing our award-winning Top Tube Bag range with some revolutionary new features. This new range offers class-leading stability, significantly increased storage capacity, and clever organisational features.

Three Sizes for Perfect Fit

Whether you’re tackling a multi-day mountain bike expedition or competing in a long-distance gravel race, we’ve got you covered with three thoughtfully designed options:

• 1.6L: Compact yet spacious
• 2.2L: Balanced mid-size capacity
• 3.0L: Maximum storage for longer adventures

The two smaller cycle bag sizes are optimised for road and gravel cycle frames, while the larger 3.0L is tuned for wider mountain bike Q-factors (though still compatible with road/gravel bikes for riders with wider stances).

These bags are particularly valuable for full-suspension bikes or unique frame geometries where traditional Frame Bags are limited. With multiple mounting options, including TPU straps or direct frame mounting, these bags integrate seamlessly with the rest of our bag lineup.

Smart Design, Maximum Performance

Our Long Top Tube Bags address the common frustrations riders experience with oversized top tube storage, giving:

• Unmatched Stability: Our unique V-Mount hardware eliminates unwanted movement and frame rub—no stem or steerer tube stabiliser strap needed
• No More Knee Rub: Vertically and horizontally tapered design with aerodynamic teardrop shaping keeps your pedalling motion interference-free
• Structural Integrity: Internal carbon struts prevent bulging, maintaining a slim profile even when fully loaded
• Thoughtful Organisation: Each bag includes a versatile divider, with optional organisation kits available for customised storage
• All-Weather Protection: Highly water-resistant 3D-welded construction and our patented rain gutter zip system keep your gear dry.

The Details Matter

True to Tailfin’s core principle of “no compromises,” our Long Top Tube Bags deliver increased capacity and organisation without sacrificing the performance that has made our storage solutions award-winners.

• Double-entry zippers allow quick access from either direction
• One-handed operation thanks to the robust internal structure
• Cable management port for clean routing of electronic cables
• Shock-absorbing insole prevents noise and protects electronics
• Reflective detailing enhances visibility in low light
• Replaceable hardware ensures long-term durability

Shop the Long Top Tube Bag >

Introducing the Rear Top Tube Bag

This compact and carefully designed bag transforms the often-overlooked space in front of the seatpost into practical, accessible storage—keeping essentials within easy reach without causing interference. Featuring:

• Rock-Solid Stability: Our next-generation “V-Mount” attachment system eliminates movement even on rough terrain
• No More Thigh Rub: Internal carbon battens prevent the bag from bulging outward
• Highly Water-Resistant Design: Advanced materials and construction helps keep your essentials dry
• Easy Access: Front-to-back zipper design means you can easily see and reach contents
• Simple Cleaning: Removable shock-absorbing insole protects your gear and makes cleaning a breeze