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Essax Shark Biomechanical saddle



Good idea, but only the most dedicated will appreciate it

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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Having seen thousands of saddles in my years of cycling I thought that the only way they could get stranger was with new colours and patterns. Then Essax brought out the Shark and I can safely say that it is the most unusual-looking saddle I have ever seen.

Maintaining the basic shape of a saddle, the Shark introduced a 'fin' at the rear which is designed to improve your power, decrease rotation and promote correct posture when riding.

When opening the box, the first thing you notice about the saddle is simply that it looks like a medieval torture device. It has the fin that is positioned to let you know when you are not sitting correctly, essentially by making its presence known in your backside. It protrudes 40mm from the saddle and sits in the centre of the saddle in the rear 30% of the seat.

It also comes in at 205g and costs £80, which for a saddle currently under consideration by the UCI and with a claimed huge amount of research behind it, isn't too bad.

The idea is that the fin will not be noticed if you are maintaining the correct position on the seat. It works by forcing you to make it comfortable to sit on the saddle, which is also where you will be optimising your position and improving your posture. It also stops you from putting additional pressure on the genitals, instead forcing you to utilise your sit bones.

So after careful fitting (Essax recommend professional fitting before use, but I just set it based on where my regular saddle has been fitted and their online fitting guide, plus several test rides) I set off to find out whether I would be impressed or permanently mentally or physically scarred.

What I found was nowhere near as horrifying as I thought.

Although you are initially aware of the fin, once you sit where it wants you to it is almost imperceptible. That being said, it is surprising how much you shift on your saddle without realising it. I found this was especially true on climbs, the winces were no longer just the 'shut up legs' variety, but also the sudden realisation that I did a fair amount of rotation when under heavy exertion.

It certainly forced me to re-evaluate the way I was sitting on my bike to avoid 'discomfort' and had the effect of making me stay in my saddle for longer. Standing on the pedals on a hill inevitably meant either staying standing for the rest of the climb or sitting back down and trying to concentrate on not being 'stuck' by my saddle, not something that you really want midway through a long climb.

Adding to this is the fact that the position that it forces you into is pretty aggressive and it is towards the nose of the saddle, meaning less surface area, so bumps feel harder with less space to dissipate the impacts. This means that even though it may improve your power and posture, it is uncomfortable to ride for anything over 45 minutes. After coming back from a ride it feels almost like I hadn't been on a bike in a year, despite a fantastic Assos chamois.

The structural build of the Shark is good, it seems sturdy and even the fin seems like it would last a long time (especially as it should theoretically not have much wear). However, I do have some reservations about the material on the saddle, which even before it has been used has a significant number of wrinkles. These are natural weak points and with the amount present, I would worry about the durability of it in the long term.

I believe that this is a saddle that many would be curious to try, and it's easy to see why. It is clear that it has significant benefits in terms of helping to improve your posture and how you sit on your bike. However, I would compare it to changing the airbags in your car with a spike to make sure you are a safer driver. I found this saddle interesting to use, but it is not something that would stay on my bike for more than a couple of weeks before I would want to be able to sit back or climb without worrying about sitting down again. It would be a product for those with total dedication to improving their posture, not somebody who is always looking to improve, but may not want the negative reinforcement and feedback that this saddle brings.


Good idea, but only the most dedicated will appreciate it

Editor's note: Since publishing this review Essax have informed us that in error we were sent a saddle best suited to track cycling or triathlon. This information was not at the time of testing listed on the Essax website, an ommision that has now be rectified. Had either we, or George our reviewer, been made aware of this fact George would not have tested the saddle as he doesn't ride on the track or race triathlons. 

Essax are now sending us a road version of the Shark saddle for review. test report

Make and model: Essax Shark Biomechanical saddle

Size tested: n/a

Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

The saddle is designed to optimise how you sit on the bike. 60% of your weight is supported by the saddle so the guys at Essax have attempted to make sure you are sitting properly. This is to make it more comfortable for the rider and also maximise the power output through the pedals.

Although it does achieve what it sets out to do in a sense, it needs to be more comfortable when you are in the 'correct' position. If the idea being that the reward is increased comfort and power, then the comfort needs to be more apparent.

Tell us some more about the technical aspects of the product?

Width: 130 and 140mm.

Weight: 195 and 200gr.

Height of the Fin: 40mm.

Length of the Fin: 100mm.

Rate the product for quality of construction:

The overall structure is solid and the fin also appears to be well made, so I would have no concerns regarding it in that sense. However, the material has several wrinkles and folds in it around the rear of the saddle and particularly the base of the fin, I would be worried about the durability of it in this way.

Rate the product for performance:

It performs well for power and repositioning you, but in terms of comfort it needs to have either more flex or padding where you are placed when riding.

Rate the product for durability:

The wrinkles and folds make me worried about how it would last in the long term.

Rate the product for weight, if applicable:

Given its additional fin, 205g represents a good weight for a saddle.

Rate the product for comfort, if applicable:

Not one for long rides.

Rate the product for value:

Hard to evaluate as it could have a profound impact for the right person, meaning that £80 is a good price. For others though, it may not be worth that money for an experiment.

Tell us how the product performed overall when used for its designed purpose

It forced me into a new riding position where I could certainly see a difference, increasing my power through the pedals. In terms of improving my comfort, I can safely say that it didn't.

Tell us what you particularly liked about the product

The improved power was great and the idea behind the product is something I also like. The idea that this could act as a personal coach just through sitting on it is something that will become increasingly popular in the next few years. Maybe not through this means though.

Tell us what you particularly disliked about the product

It did cause discomfort on long rides and the position it forces you into is not particularly flexible. When climbing I want to be able to sit back down without worrying about how I'm positioned.

Did you enjoy using the product? No.

Would you consider buying the product? No.

Would you recommend the product to a friend? No.

Anything further to say about the product in conclusion?

A good idea, but in reality something that is perhaps a step too far for performance improvement. It is also a saddle that few would want to have on for an extended amount of time and I would be interested to see if the improvements in how you sit transfers back to traditional saddles.

Overall rating: 5/10

About the tester

Age: 27  Height: 6 ft  Weight:

I usually ride: Cannondale Supersix Evo 6  My best bike is:

I've been riding for: Under 5 years  I ride: Every day  I would class myself as: Experienced

I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding, fixed/singlespeed,


George is the host of the podcast and has been writing for since 2014. He has reviewed everything from a saddle with a shark fin through to a set of glasses with a HUD and everything in between. 

Although, ironically, spending more time writing and talking about cycling than on the bike nowadays, he still manages to do a couple of decent rides every week on his ever changing number of bikes.

Add new comment


RoboRider21 | 9 years ago

Just came across this informative blogpost.

nortonpdj | 9 years ago

Yet another chocolate teapot.

RoboRider21 | 9 years ago

Interesting Review but having experienced the product myself for 9 months I have had a very different experience.

I have struggled with back pain and a problem in my right leg on long rides for years which had taken away some of the enjoyment I get from my cycling. I had numerous bike fits that were all to no avail.

I came across the Shark at the London Bike Show in 2014 and had the biomechanical benefits explained to me by Essax that seemed to explain some of the problems I was experiencing.

At that time the saddle was not available in the UK so I bought it from Spain willing to try anything.

It did take about 2 weeks to get the fit right and this is something I dont think the tester has got right if he can only ride 45minutes in my opinion.

Im nearly a year down the road now and my back and leg problem has gone and I rode ridden 7 sportives in 2014 spending up to 8hrs in the saddle no problem at all which I couldn't have dreamed of doing in 2013. With me now sitting on my saddle correctly which I obviously wasn't doing before I should be peddling more efficiently with more power according to Essax. I have no proof of this as I don't have any measuring devices for left right power but I posted my best ever year on Strava by quite a margin which suggests this could be the case.

The saddle is still in great condition so I wouldnt have any fears about the durability from my experience.

After talking to Essax I went for the small fin edition which after getting the fitting right was not that noticeable at 1st and has now become totally normal.The key point is though that the Medium fin which is the biggest and has been used in this test from looking at the picture/spec is a Track/Triathlon saddle where you sit down 99% of the time and has been reviewed as a Road saddle which kind of makes this review pointless.

johndonnelly | 9 years ago
1 like

Definitely thinking about this as an anti theft device for my runabout.

The _Kaner | 9 years ago
1 like

oooh me dangleberries...  20

Must be Mad | 9 years ago

If the idea is to keep you forward on the saddle, why not just make the saddle smaller??

Imagine the ribbing you would get if you turned up at your local club with this on your bike!

andyp | 9 years ago

sounds a good idea...but way too far back on the saddle!

jacknorell | 9 years ago

this is a saddle that many would be curious to try, and it's easy to see why

Let's see, a saddle that's uncomfortable in any position except one and so forces you into an aggressive position without any chance of variation, and transmits bumps more forcefully.

How is this possibly a successful product?

If I wanted to be poked uncomfortably up my crack, I'd head to G.A.Y., not go for a bike ride...

fukawitribe replied to jacknorell | 9 years ago
jacknorell wrote:

this is a saddle that many would be curious to try, and it's easy to see why

Let's see, a saddle that's uncomfortable in any position except one and so forces you into an aggressive position without any chance of variation, and transmits bumps more forcefully.

How is this possibly a successful product?

Triathletes. Enough said.

sincadena | 9 years ago

nobody expects a spanish inquisition... on their bike at least. would go well with a mankini..!  21

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