Ride Longer, Ride Stronger. The Inside Story of SPANK's Vibrocore Solution for Arm Pump 6

Arm pump and hand fatigue on a long descent can ruin any ride. The vibrations a rider is exposed to on the trail will eventually limit your grip strength; as you ride down rough tracks, the resulting vibrations tense the muscles in your arm. The resulting inflammation cuts off blood flow and your grip strength, while also causing pain in the hands and forearms.

Bad Vibrations

Bicycle suspension, frames, wheels, tires, bars, stems, and grips all absorb parts of this vibrational energy. Inevitably part of this vibrational energy is transmitted to the rider’s hands, which tends to make us grip our bars even more tightly as vibration increases. The combination of tight grip and sustained vibrations in certain frequencies have a negative impact, resulting in the forearm swelling we know as arm pump. 

For some riders, it can develop into bigger issues. In our testing, (you can view our Frequency Analysis Test Report White Paper Here) we found certain vibrational frequencies to be more harmful than others, as it's well documented that sustained exposure to harmful vibrations has been proven to cause medical conditions such as HAVS, VWF, CECS, and so on. 

The logic behind solving the problem is simple enough: reduce the level of vibration and you increase comfort, endurance, and performance. But as manufacturers as well as product designers, (and riders) we wanted our components to be stiff for responsiveness on the trail. Making our bars intentionally flexy just seemed to be a solution contradictory to how we wanted our bikes to ride. 

Spank developed Vibrocore™ as a solution for these negative vibrations. 

Our Process

After extensive research and preliminary testing, we partnered with a company called SGS to test a wide range of available bars as part of our development process. We identified the vibrational frequencies present in bicycles, and identifying the frequency range associated with medical risk, began the next challenge: altering the frequency.

Extensive testing of competitor bars showed that all handlebars tested tend to act as dampers. The issue was the frequencies where handlebars ceased to dissipate vibration and began to act as resonators.

Through our test process, we found foam to be the best way to address the problem. We worked with a number of foam suppliers as we went through the product development process, testing various levels of density and hardness.

How Vibrocore™ works: Changing the Frequency

Once we found what we believed to be the ideal consistency and density of the foam, we injected it into the bars. Damping the vibrations, it had the effect of shifting the resonance to a higher frequency range where it would be less harmful. Rather than battle amplitude, we effectively “took the Buzz out of the Bar.”

Innovations in Rim Engineering

After several seasons of positive rider feedback from pro-riders, consumers, media reviewers, and lab testing, we expanded the foam injection process to our rims. As your wheels are the first point of contact between you, the bike, and the trail you’re riding on, it was a logical next step.

At this point, we also took a long look at trends in rim profiles. More rigid, deeper profile carbon rims were being brought to market, touting additional stiffness — which then had to be compensated for by engineering flex into handlebars. None of this made sense to us — why stiffen the wheels only to detune your cockpit controls?

This mindset drove the development of our radial compliant rim profiles. Shifting to a wide and low rim profile (a 17mm sectional profile height and 35mm outer width, 30.5mm inner width) added radial compliance while remaining laterally stiff, reducing deflection of the wheel on rough trail, ruts, rocks, and roots and other trail obstacles. 

The forgiving responsiveness not only improved the ability of the wheels to stay on track, but riders could start increasing tire pressure again, improving acceleration and rolling speed, and reducing tire rebound. (the additional air pressure also helps avoid damage to rims)

Adding the Vibrocore™ foam core has the side effect of also increasing torsional strength and increases the overall fatigue life of the rim, while only added about 40 grams to the overall weight of the rim.

Why not Carbon Fiber?

We choose aluminum as the responsible alternative to carbon fiber. We looked into the use of carbon fiber at one point and though the material offers a lot of potential in its various applications, we decided the negative environmental impacts were not worth the cost. (even more so in the context of its use as a bar or rim material) Beyond the premium paid by the rider at the register, the resulting environmental impact of the pre and post-consumer material waste was simply too high for us.  

SPANK is one of the very few brands of its size in the world, with in-house design, development, and manufacturing of our products. The toxic emissions that workers and local communities are exposed to around carbon fiber manufacturing facilities matter to us.

There’s also the safety aspect for the rider. Having witnessed first hand the consequences of catastrophic failures of a carbon bar, we’d prefer a bar that will bend before snapping in two for the riding we do.

For more information, visit Spank-Ind.com, or shop for SPANK Vibrocore™products online at TheGravityCartel.com