Vibrocore™ - The Inside Story



Injected into Spank Industries handlebars, it reduces the harmful vibrations which can lead to hand-arm numbness and fatigue (HAVS), as well as arm-pump (CECS), while also increasing overall bar stiffness and fatigue life.

Whether its safety, price, or environmental responsibility, alloy has always been a favorite of many mountain bikers for bars. However, it wasn’t until SPANK Industries introduced its patented Vibrocore™ technology that alloy bars could match the stiffness, comfort and lightweight of carbon bars. Vibrocore™ adds a mere 25g to 30g to the bar weight. With Spank Oozy and Spank Spike models ranging from 760mm to 800mm in length, and rises from 5mm to 50mm, the benefits of the Vibrocore™ technology have been engineered into bar geometery for trail riding, enduro and XC, downhill racing, freeride and slopestyle, and all for under $100 MSRP.





Lab and rider tested and proven to reduce the short term effects of hand-arm numbness and fatigue (HAVS), and reduce the long term risk of arm-pump (CECS).


The complex core increases inner wall strength resulting in increased fatigue life and a stiffer feeling bar without compromising weight since it allows us to produce our bars with a thinner wall.

As we ride, vibrations are transmitted through the bike into our hands and arms. The range of vibrational frequencies experienced in mountain bike riding is between 2Hz to 200Hz, although the most common vibrational frequencies experienced in mountain bike riding occur between 5Hz to 50Hz.

Sustained vibrations between 8Hz to 50Hz are proven to be medically harmful and result in what we know as hand-arm numbness and fatigue, (HAVS), and in extreme cases, arm-pump or CECS. This medically harmful range of 8Hz to 50Hz coincides almost exactly with the most common frequency occuring in mountain bike riding.

All handlebars act to dampen some of these harmful vibrations. Yet all handlebars also have a unique frequency at which they resonate - thereby increasing the harmful vibrations. Resonance typically occurs between 12Hz to 25Hz. This creates “The Perfect Storm” and the highest risk towards causing hard arm numbness and fatigue and arm-pump.

SPANK aimed to move the handlebar’s natural resonant frequency into higher ranges, rather than battle amplitude. The reason for this is twofold. Higher frequencies are less common in cycling and are less harmful to the human body. Vibrocore™ is how we achieved this, effectively “taking the Buzz out of the Bar”.



The tell-tale scar associated with corrective surgery of CECS (Arm-pump).


Most riders, at some time in their riding life, will have experienced some sort of arm pump (CECS) or hand numbness and fatigue (HAVS). Many of us accept it as an unwelcome part of mountain biking and simply carry on, hoping to be able to one day be fast enough to beat it. Unfortunately, arm-pump is often misdiagnosed, and in many cases ends in surgery commonly associated with motor cross riders, and more and more frequently in mountain bikers.

ARM-PUMP (also known as CECS or Chronic Exertional Compartment Syndrome), is a condition commonly seen in endurance and motor sports where individuals are exposed to sustained low frequency vibration. Arm-pump refers to a state of acute pain and loss of muscle performance, caused by excessive swelling of muscles in the forearm.

Muscles are bundled in a strong, but relatively inflexible membrane called fascia and can grow in volume up to 20% as blood rushes in to provide energy during periods of exertion. As the fascia membrane is not able to stretch to accommodate this swelling, the muscle becomes more and more tightly bound, inducing pain and inhibiting blood flow which leads to muscle under-performance and over-fatigue.




SPIKE 800 Race Vibrocore™

OOZY 760 Vibrocore™

"Light but tough and smooth, control boosting, fatique reducing bars. Even in a crowded market a really outstanding product can come along that resets the benchmark, and when it comes to alloy bars, that’s exactly what the Vibrocores do."


"Spank’s bar has unequivocally failed to create a buzz.

I tested the Vibrocore Race Bar back-to-back against the leading carbon and aluminium handlebars in the Pyrenees and the LakeDistrict, on extended rocky descents, and found the differences between the three noticeable.

ln terms of stiffness, the Spike is solid and steers precisely, but there’s a distinctly deadened, dull sensation that’s similar, yet somehow different, to the feeling you get from the best-damped carbon bars.

High frequency trail chatter was noticeably more muted, leaving my hands fresher and less sore at the bottom of touqh descents. The shape and feel of Spank’s continirously tapering bars is excellent, but with Vibrocore it now also offers an advantage that isn’t found with any other handlebar on the market. The fact that this innovative feature only adds 25g to the weight, and very little to the overall cost, is even more remarkable."

Mick Kirkman - MBR



"The most important contact point with a bike is the handlebars, so why not choose bars that not only feel comfortable but also provide a better ride?

From the moment we dropped into our favourite downhill run, we immediately noticed a difference.

The Vibrocore™ technology didn’t take away the feel of the terrain but still reduced the hand-jarring distractions of it. We were definately impressed with the performance of these handlebars and the extra fun they added to the ride by keeping our hands feeling fresher.

We would definately recommmend them to our closest friends."


The highlight of our experience was the Vibrocore feature.

Hand fatigue and arm pump can be a big bummer for some, especially on bike trips where you’re putting in long days, one after the other. Being able to reduce fatigue and arm pump could be huge for riders who have to deal with it.

For those who don’t have to deal with it, the carbon ‘feel’ of this bar for the price of an alloy alone makes it a cockpit option definately worth checking out.

There can always be improvements in our industry, but we can’t think of any with this product.

Fred Robinson - VITAL MTB 4.5 STAR



Polygon UR Team owner, and Enduro and DH athlete Fabien Cousine, suffered arm-pump to the point where repetitive surgery was still only offering temporary relief from the symptoms. CousCous was considering retiring from competition when Spank Industries owner and chief engineer Gavin Vos offered to dedicate R&D resource to exploring solutions.

Through consultation with CousCous, and invaluable input from team riders Mick and Tracey Hannah, the Spank Industries Vibrocore™ was put into rider testing with UR team before successfully being adopted into production of all Spank SPIKE and OOZY Vibrocore™ bars.

(Left) Polygon UR Team: 2017 UCI DH World Cup Lourdes, 1st Elite Men (Alex Fayolle), 2nd Elite Women (Tracey Hannah)




Wondering what resonance is and why its a problem?

Take a look at this video footage of the infamous Tacoma Narrows Bridge collapse of 1940, otherwise known as “Galloping Gertie”. The first Tacoma Narrows bridge collapsed because of the very simple physical phenomenon called resonance.

Now imagine when your handlebar starts resonating within the same frequency that is medically proven to be harmful. Starting to understand how your hands and forearms take the brunt of that resonance?

Vibrocore™ takes the proverbial gallop out of Gertie.




Click here to download the white paper.

Includes Test Lab data and Analysis.

Test Lab Results


Carbon fibre transmitted higher levels of harmful vibrations into the riders hands. We put a number of conventional 31.8 alloy and carbon fiber handle bars to the test at Taipei’s SGS Test Laboratory.



Each of the handlebars tested reduced amplitude of low frequencies between 1 and 8Hz, and above 30Hz as they enter what is known as "damping mode".

Materials and construction is important when looking to move vibrational energy into less harmful frequencies, or in this case, less commonly occurring frequencies. SPANK tested their Vibrocore™ bars against carbon fibre, 35mm, and traditional 31.8 bars. Stiffness and flex can be built into these using construction techniques, but on test, carbon fibre transmitted higher levels of harmful vibrations into the riders hands. In addition to this, carbon fibre is not made from an infinitely recyclable base metal which has obvious environmental repercussions.

Vibrocore™ handlebars from SPANK not only move vibrational energy into the less damaging range of frequencies, but the materials used are not as harmful in the long term. Even the Vibrocore™ material is biodegradable over time.

The combined effect is at least a 30% reduction in harmful vibrations transferred to the rider’s hands, when compared to carbon fibre handlebars.

How did Spank test these factors?


Spank Industries, in cooperation with SGS Labs, developed a series of tests, with the goal of quantifying the vibrational characteristics, damping rates, and resonance effects of various handlebar types.

Vibrcore™ handlebars being tested at SGS Labs.


An acceleration test machine fixes the handlebar in a typical riding orientation. This machine can move upward and downward at controlled frequencies, and at controlled acceleration (G input or Gi). Thus the frequency and amplitude of the vibration can be controlled precisely. The handlebar is loaded with weights at the barends, which are representative of the rider’s weight on the bar. Sensors are mounted at each barend, to record resulting vibrations which would be transmitted to a rider’s hands (G output or Go).

The test machine is set to keep a constant amplitude (Gi), and vary slowly from a low frequency (Hz) to higher frequencies by adjusting the rate at which it vibrates, while sensors record vibrational data at the barends (Go). Here we can see clearly that even with a fixed input amplitude (Gi), the amplitude of vibrations exiting the system through the handlebars (Go), changes greatly as frequency varies, and peak at a distinct vibrational frequency range. This is the handlebars natural resonance frequency.

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