Canyon’s K.I.S, RockShox’s Flight Attendant and frames built using additive manufacturing might be improving mountain bike performance but this rise in technology is also seriously complicating the sport. Set to make the sport even more tech-heavy but help riders shave seconds off a run is Rimpact’s Mass Tuned Damper. We headed to the brand’s HQ to learn exactly how this F1-inspired tech can benefit your ride.

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Tuned Mass Dampers are incredibly common in the industry. Not only are they used to stop NASA’s rockets from toppling over when stationed but they also keep the towering Burj Khalifa upright. However, the inspiration for Rimpact to explore the concept of adding the tech to a mountain bike came from Fernando Alonso’s championship-winning Renault Formula One car that the FIA banned as the mass damper was a ‘moveable aerodynamic device’.

In the case of Alonso’s Renault, it allowed the Spanish driver to attack the raised curbs on a corner’s apex much more aggressively as without tuned mass dampers, doing so would unsettle the car, lose downforce, and grip making it much slower. Over the course of a 190-mile Grand Prix, being able to drive around corners with such confidence and stability gave the driver a huge advantage that was used to great effect during the 2005 and ‘06 campaigns with the tuned mass dampers being referenced as to why that car was so fast.

And therein lies a small hint of why Rimpact reckons that tuned mass dampers are beneficial for MTB.

What is a tuned mass damper?

Tuned mass dampers come in several forms but in layman's terms, they’re units tuned for specific applications that contain suspended weights. For Rimpact, that’s a chunk of tungsten held between a pair of springs. Tungsten has been chosen for its density, as a stainless steel weight, for example, would have to be much larger to achieve the same mass. It also won’t be as compact and will struggle to fit in the small and usually unused area of a head tube.

Tuned mass dampers work by creating a vibrating mass that moves out of phase, opposite to an outside force. So if you were to ride into a root, the front end would be shifted upwards, whereas the mass in the tuned mass damper would lower in its unit and vice-versa – thus absorbing targeted frequencies of vibration. The spring rate dictates which frequencies are targeted and we’re told that when it’s brought to market, Rimpact’s Tuned Mass Damper will come with three spring rates but more on that later.

Otherwise, Rimpact’s tuned mass damper for mountain biking takes the place of a star-fangled nut in the steerer tube and fits a bike identically to OneUp’s EDC Tool and Threadless Carrier, among other head tube stored things. It then weighs 420g.

The early prototypes didn’t work…

With an idea inspired by Formula One, Matt began testing crude prototypes of a tuned mass damper designed to sit within a mountain bike head tube. However, those prototypes showed no real value or made any positive effect on a bike’s ride and its ability to dampen vibrations. Matt, however, was convinced he could get it to function, particularly due to the industry's use of tuned mass dampers in precision tooling by NASA and buildings constructed in earthquake zones.

“We made some crappy prototypes and none of them worked. We made some more prototypes and none of them really worked but we were still driven by this idea that it’s so useful in lots of other industries.”

How does a tuned mass damper affect a mountain bike?

Although Rimpact’s Tuned Mass Damper isn’t designed to hold up mega-towers, mountain biking and vibration go hand in hand and vibration is a contributing factor to why we feel fatigued in our arms and shoulders long into extended descents. The whole idea of this damper is to reduce harsh vibrations to allow the rider to ride faster for longer. 

“There have been tonnes of studies into vibration in mountain biking. There was a thesis that unearthed a lot of information that the vibrations that a downhill rider feels can be many times greater than what a road worker would feel when operating a jackhammer. Vibration has been proven in the medical field to be pretty negative and can really be detrimental to your health.

So although we weren't ever looking at it from the health perspective it was very clear that vibration affects mountain bikes and as with everything if something is vibrating, it isn’t stable, it’s harder to control, it’s hard to focus and your brain doesn’t work as well when it’s trying to damp something.

If you can rob all of that energy from a system and make something smoother, you’ll be able to pilot it better. You’ll be fresher when you ride the bike, etc.

So that’s what we’re focusing on, can we design a mass damper and tune it to the particular frequencies that happen in an advantageous way to make a bike better.”

How is the tuned mass damper different from simply adding weight to a bike?

Adding weight to a bike is common among the elite downhill circuit where riders eke out extra suspension performance from their bikes by increasing unsprung mass. Weighing short of half a kilo, Rimpact’s technology looks to do a similar thing but is designed to do more.

“If you add weight to a bike you will improve the sprung-to-unsprung weight ratio of the bike and that will make the suspension work better, effectively, and stabilise the whole system but the bike will still feel vibration. The vibrations that we’re referring to are not high-energy, low-frequency vibrations – the kind that compress your fork.

These are the frequencies that vibrate so fast (hundreds of times per second) and travel up the fork material and through the steerer tube and then the handlebar, through your hands, and eventually shake your eyeballs around in such a way that you don’t notice it’s happening but you can feel it.

So just adding weight to a bike will improve its stability and, to some extent, dampen some vibrations. However, a mechanical device that is both heavy (to do that part of the job) but has an extra mechanical advantage can be tuned directly to those frequencies and will give you double the benefit.”

This tuned mass damper adds a bit of weight, so the bike will benefit from more weight but because it’s damped, it sorts out a greater range of vibrations as well.

“Yes, and to add to that, it’s also in the steerer tube which is on your steering axis so it’s adding weight in an area that doesn’t really affect the handling of the bike, so to speak. Pitching the bike left and right isn’t going to feel any different. The bike will just feel more controllable.” 

Mountain biking is seeing a focus on carbon handlebars that are being built to absorb vibrations. How does a tuned mass damper do this differently?

The harsh reality of cockpit-based vibrations isn’t something that hasn't been addressed in the industry as there are already loads of brands attempting to tackle fatigue. Many focus on handlebars with brands such as OneUp Components designing handlebars that flex vertically while providing stiffness along the steering plane. Another brand is Fasst Company with the Flexx bar that utilises elastomers to absorb vibrations by adding damped travel to the ends of the bar. 

“When you’re designing something like a carbon handlebar to be compliant and absorb vibration, you can certainly try to tune towards to certain area of vibration that you want to target, like a buzz but intrinsically with that material, you can only do so much to the handlebar’s flex before it has negative implications on the way the bike handles.

With the tuned mass damper, the world’s our oyster. It can move as much as you want and it can weigh as much or as little as you want and it can target a very specific field of vibration.

If you were to measure it on a graph, you would see a large spectrum of different vibrations that the bike will see and you can target one specifically which is a lot harder to do with physical material. You have to think about the structural integrity of the handlebar, and so on.

But we’re not saying that you should run an alloy bar to get the benefit [of the damper]. They’re two different things. Do everything you can in one package, so run inserts that’ll dampen some vibrations. Spank offers some vibrocore things that help. ButterCups on certain forks and a carbon handlebar, in conjunction with this [tuned mass damper] you’ll be getting a really smooth bike which means you can focus and ride better.”

The tuned mass damper will come with different spring rates, how do they focus towards different levels of impacts?

A lot of mountain biking technologies provide performance based on a rider’s weight and riding style. Volume spacers, coil shock spring rates, and air suspension require setting up to account for weight and riding style. But that’s not the case for the Tuned Mass Damper which is another hurdle to clear.

Instead, Rimpact’s motorsports-inspired tech is something that’s to be tuned to the trail that the rider is riding, rather than the rider themself.

“We haven’t exactly dialled in how they’re going to be advertised in terms of ‘will spring A, B or C be for a certain type of riding or a certain impact level'. The tuned mass damper is more focussed towards certain frequencies that you see and different types of riding that’ll see different levels of this frequency occur.

I’m currently looking at it that the lightest springs that this will ship with will let the system oscillate more freely, which means it's easier to excite. This means that less intense vibrations excite it easier, and those are the ones that’ll be cut out. Then those that are more intense will move the mass in a greater way but it’ll be less effective for the higher frequency vibrations as it’s not tuned for that.

On the flip side, the heavier tuned springs that’ll ship with the damper will be tuned towards heavier impacts.

So certain trails, such as a flowy blue trail with nothing major on it, the rider will benefit from the lighter spring rate. A downhill track with big hits and high speeds might benefit from a heavier spring rate. But that’s by no means the set rule because in testing we found the opposite some tracks are different from others and there might be a certain section of that track where one spring is favourable over another, and all we can do is offer that tunability to the user

As long as the spring rate and the mass pair together to create a total outcome that’s in the right region, it’ll work. So we just have to dial it into that area.”

So it’s more specific to the trail than it is anything else?

"Yes, so the user doesn’t make any difference. The speed in which you hit things does, so you can say that the user makes a difference but the weight or the ride style of the user doesn’t change things much. It’s more the actual physical inputs in the front wheel from the trail that make the difference.”

• www.rimpactmtb.com

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