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Product Review: Fizik Antares VS K:Ium Saddle

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VS models are for riders who want a fi’zi:k saddle with a relief zone. This is a solid-base saddle with an ergonomic channel spanning the length of the saddle. The saddle features a 5mm-deep central relief channel.

k:ium is a fi’zi:k proprietary rail formulation. It’s the combination of a particular metal alloy, a specific tubular design and a special finishing process which increases fatigue performance on the rail surface.

Fizik Spine Concept – Antares VS is for The Chameleon: Medium Spine.

If you have an intermediate degree of spinal flexibility (approximately 90 degrees between your straight legs and your back when bending over as far as you can, keeping your legs straight a shoulders’ width apart), you are a chameleon. Your degree of spinal flexibility helps you so far, before you need to rotate your pelvis slightly to achieve fully the performance position.

You will benefit from the increased width and slight curvature of the Antares shape.

Provided this saddle’s width isn’t too narrow for them, some women may find this model comfortable due to the presence of the relief channel.


  • Solid base ensures saddle’s structural integrity is unaffected.
  • No reduction in saddle’s surface area, therefore no subsequent increase in pressure.
  • Relief channel spans the length of the saddle, allowing the rider freedom to move along it.
  • Edge of relief channel is a gradual change in the foam mould leaving no sharp edges that might cause pressure points.
  • Shell: Nylon Carbon Reinforced
  • Rail: K:ium 
  • Cover: Microtex
  • Thigh glides: Glossy Microtex
  • Padding: Low density with relief channel
  • Integrated Clip System: Yes

Fizik Antares VS K:Ium Saddle Review:

Fizik are a Spanish brand, and they have been riding a variety of different saddles for a long time. Antares vs. K:Ium is their latest attempt to create a truly unique solution. However, how does it fare?

The Antares is a unique compression type welted design. This is a true ‘compression’ saddle, as the saddle features four pockets injected with the high-tech material. It also features a double layer of foam that can be either kevlar or kevlar-injection as well as several air channels. Obviously this causes more rider comfort than other designs. The K:Ium saddle, however, is made with a high-density foam called ionic foil. This material is more similar to Kevlar and is very strong and resilient. Yet it is much more flexible than the ionic foil used in the Antares. The advantage is that it allows a very high level of skin-folds across the saddle surface. Added to this, it allows for the smallest adjustment of the saddle. This is particularly important for shorter riders.

The K:Ium Evolution was made for singles and has a rider-specific interface. Most bikes have a minimal cartridge seatstays with the saddle base. Unfortunately, this is a barrier to the rider wearing the saddle to full extension. This is not a problem with the K:Ium Evolution. The saddle base features a carbon fiber plate that forms a semi-oval cavity that is equal to the width of the saddle. With this shape, the saddle will act as a single adjustable channel, and has the ability to fully adjust to accommodate your body, and not change shape even if you undergo a full press against the bar. With the K:Ium Evolution, the carbon fiber plate is nested into the saddle body. This allows to create a much more rigid platform to support your weight, as well as the increased pressure of the saddle.

Fizik Antares Versus Review: Features: This is a simple yet unique design. Some may see the K:Ium Evolution as lacking in rigidness, as it is a one-piece monocoque saddle. However, this is where the benefits end for this saddle. Its design allows for freedom of movement across the saddle surface and the briefest adjustments to help fit the rider into the saddle. However, this design has the smallest of component parts to the saddle, and that is a significant disadvantage.

Fizik Antares vs Fizik Spine VS: So which is more comfortable? Well, you obviously need to determine why you are using either saddle. Both are very comfortable and offer a full range of curvature and movement. But if you are using the strap-down version, then the K:Ium Evolution could be somewhat superior in this regard. Furthermore, the Antares is a bit more flexible than the K:Ium Evolution, in addition to being more comfortable for the rider.

Fizik Antares vs Fizik Spine VS: The primary benefit of the K:Ium Evolution is the greater compression of the saddle. This is the primary reason for its success. Fizik may not have been able to achieve that with the Antares, but it is definitely a bold attempt.

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Comparison Test:

A comparison between the two saddles features an equal amount of vertical and oblique motion. That means a starting position and a fine adjustments to the steepness of the slope, as well as increased oblique and vertical motion. This test also features a variety of levels of obstructions, and a clear measurement of the saddle’s flexion.

After this test, the K:Ium Evolution showed an advantage in the vertical angle as well as the oblique angle.

Comparison Test: Features: The features are similar, but the K:Ium Evolution is clearly the winner. It has much more rigid and consistent flexing support, and can adjust to any change in inclination of the saddle.

Fizik Antares vs Fizik Spine VS: Features: The features are very similar, and they must be hard to distinguish for a novice rider. Fizik could have a slight edge to it if they wanted, although the K:Ium Evolution maintains more consistent flexing.

The K:Ium Evolution offers more adjustments to the position without the need to make like the saddle a triangle. Fizik could take a closer look at these deviations. But, in the end, it is the ability to make quick and even adjustments that makes it a winner.

Conclusion: The Antares Vs K:Ium saddle system offers a combination of functional stability and comfort. The only flaw is that the K:Ium Evolution’s construction is a one-piece monocoque, and the saddle may not be as rigid as the Antares system. But the Fizik saddle system offers a much greater adjustment for a less stiff saddle.

Get an expert opinion from the Master Bike Maintenance Experts at Sport Science UK today.

Xtreme Damper Technology

Xtreme Damper Technology

The Fizik saddle is made with Xtreme Damper Technology. Xtreme means “limitless” in French.

The Xtreme Damper System is a unique system. It has two planes where the saddle fits its shape and which are compressible. In addition, the saddle adapts to changes in the rider’s position, aligns its shape to the rider’s middle back and centre of gravity, while also subtly adjusting to remove pressure points which are considered to be the cause of a number of problems with saddles.

It is the use of Xtreme Damper Technology that is the cause for the advantages in set-up of the K:Ium Evolution. The Xtreme Damper Technology allows increased compression to all of the saddle’s surfaces and guide rails. The result is a very rigid and well-supported saddle, to enhance the rider’s ability to adjust the ride.

The Fizik Spine VS adjustment system in K:Ium Evolution uses a wide and smooth opening, placed to the centre of the spine, to accommodate a flexible that adjusts the saddle to the correct position to meet your requirements.

The Fizik Vistrike, and the Fizik Anita, are two other Fizik saddles that offer this technology.

The Saddle Concept

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The idea behind the Fizik saddle concept was to improve the rider’s comfort as much as possible. The system has a number of features, including:

1.  Four channels to properly fit the rider and for the rear wheel to be seated in a natural position for a nice ride.

2.  Ease of set-up and removal: The rider can easily adjust the position of the saddle, and the system will hold the rider in the saddle throughout changes.

3.  The ability to adjust the saddle to the rider’s weight and needs.

4.  The ability to effectively lower pressure to the rider’s back and seat: The saddle eliminates stress points that could bring on pressure points in the hips and knees.

5.  The ability to increase pressure to the rider’s back and seat: The saddle is compression-fit to the rider’s back and seat so that pressure can be applied as the rider rides.

6.  The ability to lower resistance by way of several close-fitting points along the seat and saddle: These points provide a smooth resistance hit, so the rider does not feel their climbing ability limits their comfort on the road.

7.  Mandrel-bent tubes and carbon fibre tubes to improve compaction and relieve pressure: The tubes distort more with the rider, making the saddle more rigid and working towards zero resistance. (The K:Ium Evolution does not use mandrel-bent tubes.)

8.  The ability to cause the rider’s position to adjust: When riding uneven surfaces, the saddle has a tendency to give way in an area. If the rider does not adjust, the saddle might give way in the saddle pad, the saddle pillar and the saddle.

9.  The ability to soak up the rider’s back: When the rider does not adjust the position, there could be situations where the rider’s back breaks contact with the bike. This could ruin the rider’s enjoyment. The Fizik system uses a knurling on the back of the saddle that concentrates in one area to absorb this pressure and eliminate the breakage.

10. The ability to change the rider’s comfort: When the rider is not adjustment the seat and saddle, the rider’s comfort may be compromised. This is addressed in the Fizik system with a flat saddle group on the lower part of the back. This means that the saddle’s shape can change to give the rider a comfortable riding position.

At its core, the Fizik saddle is strong, comfortable and fits the rider well. However, the Fizik skin system adds a number of other qualities that make it a much improved system.

The Fizik Smart Fit:

During the sets-up of the Fizik system, the rider must first make sure that the saddle fits the rider. This is done by using an accurate seatpost drop wrench to check that all of the saddle’s fittings are in place. Failure to fit properly could allow the rider to be considerably impacted by the saddle.

Once the front and rear riders defined the fits and the size of the bike, it was time to move to the saddle. 

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Written by Mark Adams

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