Tailfin Top Tube Bag review

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The Tailfin Top Tube Bag has been designed to offer easily accessible storage on the go at a price of £55 / $70 / €65.

Well known for its bikepacking bags, British brand Tailfin offers a range of storage solutions for mountain biking that are said to be stable, dependable and robust enough to take repeated knocks out on the trails.

The Tailfin Top Tube Bag has a sculptured shape and tapered design intended to eliminate knee rub when pedalling. It’s available in three sizes – 0.8l, 1.1l (tested) and 1.5l.

Each bag comes with three straps; there are two 185mm straps and one 360mm strap, aimed at accommodating all frame sizes.

The bag can also be mounted directly to frames with spare bottle boss mounts, and all mounting screws and washers are included.

There are two V-mounts on the underside, a patented design that's said to eliminate movement.

These are coupled with soft rubber straps that have been developed to eliminate frame rub and provide a stable connection, without the need for a stabilising strap around the stem.

The bag’s body is made from 210D Hypalon and 210D Diamond RipStop material, with a welded construction that Tailfin claims is fully waterproof.

Additionally, the bag features internal cushioning and a cable port (for USB charging GPS devices, for example), which is designed to be waterproof. The exterior features reflective detailing.

The smaller 0.8l bag (£52 / $65 / €60) has been designed for road and gravel, while the two larger sizes – 1.1l (£55 / $70 / €65) and 1.5l (£60 / $75 / €70) – are designed for mountain biking.

The latter two sizes are also available with a flip lid rather than a zip closure at an additional £5 / $5.

I tested the 1.1l bag, which weighed 175g when unloaded, with straps included.

Tailfin Top Tube Bag performance

The Tailfin’s stability when mountain biking is remarkable.

Thanks to the V-mounts and rubber straps, the bag stays securely in place even on rough terrain, and I didn’t experience any frame rub during the test period.

The inclusion of various strap sizes ensures it fits a wide range of frames, making installation and removal quick and easy. The rubber straps also allow for a secure fit, with ends that can be tucked under the V-mount to keep everything tidy.

Because the bikes I tested it on didn’t have suitable frame mounting bolts, I couldn't evaluate stability with this mounting option.

My tests confirmed Tailfin’s fully waterproof claims ring true. I faced some extremely wet conditions during testing, but my belongings remained dry and well-protected from the elements.

The 1.1l capacity offers ample space for essentials such as a trail-side repair kit, first aid equipment, snacks and a phone. An internal mesh pocket keeps your phone easily accessible while you’re on the move.

Durability has been impressive, with internal padding safeguarding contents and minimising rattling. Some rattling may occur on rough terrain if the bag isn’t fully packed, but this is to be expected.

While testing the 1.1l size, I found it didn’t interfere with pedal strokes, ensuring a smooth and comfortable ride.

However, over-stuffing it can lead to knee rub because it affects the sculptured and tapered design. It’s something to keep in mind when packing because its shape can be altered and make contact with your knees.

It also might not be the ideal choice for technical and gnarly terrain, where a more dynamic riding style is required. In such conditions, my knees occasionally hit the bag, which was a bit annoying.

Tailfin Top Tube Bag bottom line

Unlike bikepacking, top tube bags aren’t common in mountain biking, so you may get some funny looks.

However, the Tailfin Top Tube Bag is a great option if you want easily accessible storage that's secure and won’t damage your frame.

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