Home > Other Fun Stuff > Prototypes & Concepts

Tuned Mass Dampers for Skyscrapers, Rockets, F1 and… Mountain Bikes?

rimpact tuned mass damper mtb mountain biking prototype
36 Comments
Support us! Bikerumor may earn a small commission from affiliate links in this article. Learn More

Rimpact, a UK-based manufacturer of high-end tire inserts, is developing a Tuned Mass Damper (TMD) for mountain biking. Suspending a Tungsten weight between two coil springs, inside a package that slots neatly inside the fork steerer tube, the TMD is strategically positioned to damp vibrations induced by bumps and compressions experienced on the trail.

A first-of-its-kind for mountain biking, this chassis-stabilizing component is still very much under development, but the accelerometer data collected by the engineers at Rimpact are showing promising trends. And, more importantly, they say it makes the bike feel better on the trail, while making riders faster at the same time – that’s from blinded back-to-back testing versus placebo, for anyone choking on their morning coffee.

Here’s the backstory, and how the development process is going so far.

rimpact tuned mass damper prototype
Rimpact’s Tuned Mass Damper lives inside the steerer tube. With the headset top cap threading into its upper portion, it replaces the star nut and removes play from the headset with a brace plate at the base of the steerer – much like the OneUp EDC Tool installation.

Rimpact is Developing a Tuned Mass Damper for Mountain Bikes

First up, it’s pertinent to answer the following question….What is a Tuned Mass Damper?

In essence, it is a weight suspended between springs, that is positioned inside a dynamic structure in order to damp that structure’s movement or oscillations. As the structure moves, the weight moves out of phase with it, removing energy from the system and bringing it back to a more neutral state earlier on. You may also see it referred to as a harmonic absorber or seismic damper, the latter conjuring up images of the famed devices found inside the Taipei 101 or Shanghai Tower, that have both become something of a tourist attraction.

The 660 metric tonne tuned mass damper inside the Taipei 101 tower is the world’s largest and heaviest example. Credit: Zach Overholt

What on earth does that have to do with mountain biking? I’m getting there, but first it is interesting to look at the use of Tuned Mass Dampers in motorsport.

While TMDs in skyscrapers serve to reduce the tower’s maximum amplitude, or how much they sway during tremors or high winds, the TMDs used in motorsport applications are designed to improve the dynamic stability of the car when it hits bumps on the road, and to hold it in a more aerodynamically favorable position thereafter. Vertically positioned on the car’s chassis, right between the two wheels, the TMD acts to bring the nose back down quickly if it is deflected up by a bump, or raised up under rapid acceleration.

renault f1 car alonso tuned mass damper banned by fia
Alonso Renault F1 Car benefiting from a Tuned Mass Damper. Credit: David Acosta Allely / Shutterstock.com

We are informed that the TMD implemented very successfully by Renault offered such an advantage to Alonso that in 2006, the FIA issued a technical bulletin declaring the mass damper illegal on the grounds that it was a moveable aerodynamic device. It was this application of the Mass Damper that caught Rimpact founder, Matt Shearn’s attention.

Matt thought to himself, “if it’s good enough for them [F1 drivers], then perhaps it could be good enough for us [mountain bikers]”. And so, for the last 2.5 years, Matt has been quietly working away on a TMD for mountain bikes.

The Rimpact TMD Prototype

The Tuned Mass Damper under development by Rimpact looks much more like the F1 TMD than it does the examples used in the skyscrapers that are sub-optimally located in earthquake-vulnerable geographies. That’s because it is designed to stabilize movement through a single plane (up and down), rather than the 360° movement exhibited by a tower.

rimpact tuned mass damper prototypes early stage development
Early stage prototypes of the Rimpact Tuned Mass Damper

Importantly, it proposes to offer similar advantages – less so in regard to aerodynamics of course, but certainly in the way of chassis stability, and subsequent ease of handling.

“I’ve been trying to decipher whether there would be any use in mountain biking – first of all trying to work out how the thing works for one – and if it did work, how would it change the way we ride bikes – whether it would make the bike better in any way, or whether it would hinder it”

Matt Shearn, Founder of Rimpact.
rimpact tuned mass damper internals prototyping components
A small sample of the prototype parts used in the development of Rimpact’s Tuned Mass Damper

After much thought, he concluded there was at least value in building a prototype to see what it did. The first prototype was as basic as it gets; a couple of “random springs” suspending some putty inside a clear acrylic tube. Matt strapped it onto his bike and slammed the front wheel into the ground, just to see the putty weight oscillating between the springs. Holding onto the bars, he was interested to see if he could feel any difference with or without the contraption.

It’s about as un-scientific as it gets, but you have to start somewhere, right? With his interest piqued, it was time to get serious with a more robust prototype and some accelerometer data.

Fast forward to around March/April of this year, and Rimpact had a working prototype, the influence of which on ride feel was unmistakable.

Does a Tuned Mass Damper actually work for MTB?

That’s still to be confirmed, but based on their experiences so far, Matt Shearn and the team at Rimpact are quietly confident.

“We all felt like it was making a difference, and our Strava results suggested it was making a difference. But, it was totally anecdotal but there wasn’t enough scientific rigor there to prove that it was actually working”.

Matt Shearn

With the TMD device in a jig, Rimpact have been able to corroborate with the use of accelerometers that they see a reduced amplitude of force at the handlebar with the device installed, as compared to control. At least in this very specific scenario, that arguably isn’t super relevant to trail riding conditions, it undoubtedly is having an effect.

rimpact tuned mass damper testing in jig
Rimpact repurposed their tire insert test jig to test the effect of the Tuned Mass Damper on the g-force felt on the fork crown and handlebar

Matt explains, “If you were to somehow be able to visualize the vibrations that pass through the bike during the rising of your handlebars [when the front wheel hits a bump], the vibration is travelling up through the bike and oscillating at a really high hertz, but the mass is offsetting some of those vibrations so you’re feeling them less. It is both bringing the total amplitude of force down, but also reducing the noise from vibrations coming up through the bike”.

At this stage, we want to see actual data from the trail.

rimpact tuned mass damper accelerometer data graphs

The above graph shows the total measured force through the handlebar, as recorded by accelerometers, over a three minute trail. The Y axis is G force and the X axis is time. Data from Run 3 is without the TMD, and Run 4 is with the TMD – with Rimpact’s “Medium” springs fitted.

Matt explains, “It’s hard to see visually what is happening here but Run 4 measures 19% less total G forces recorded compared to Run 3 when normalized to the same time frame (as the run took less time to complete, we removed this excess data from the slower run to more accurately compare the readouts). Run 4 took less time to complete which is evident by the force spikes on the graph running out of sync and points to a system that works to help the rider go faster. Whilst this is just one graph the results across the day of testing and other tests we’ve performed yield similar results. Currently we are conducting many hundreds of test runs to validate this analysis”.

On top of the accelerometer data, Rimpact also have a bank of more subjectively captured data in the form of rider feedback. Matt tells us that anyone who rides the TMD is able to feel a difference in the bike’s handling. They say the difference is subtle, but they feel like they ride better, that they carry more pace through corners, and they don’t feel the spikes of compression through the fork when they hit big roots. They don’t get those harsh feelings through the bike and they simply prefer riding with it, versus riding with the placebo version.

tungsten versus steel tuned mass damper prototyping
Finding the right material for the suspended weight was key; on the right is a 79 gram steel weight, and on the left is a 204 gram Tungsten weight of the same dimensions.

When can I buy one?

Alas, that is also to be confirmed. Matt is clear that he wants to prove the Rimpact TMD has a beneficial impact for mountain bike riders before he sticks it on the market. He currently has a number of TMDs out in the wild, with test riders conducting blinded back-to-back testing of the real thing versus a placebo tube.

He hopes to amass a large database of evidence – whether it is evidence in favor of the TMD or against it – from a multitude of different riders across a multitude of trails.

If the data proves favorable, and the Rimpact team can show that their Tuned Mass Damper is improving ride feel, helping riders go faster, or even simply reducing fatigue, they will certainly bring it to market.

Matt is considering offering a variety of spring rates that will each perform best over a set range of G-forces that are experienced on different terrain, but the details of that are still being figured out.

rimpact tuned mass damper mtb mountain biking prototype
The current working prototype weighs around 310 grams

Thoughts on the Rimpact Tuned Mass Damper

Personally, I think this device is absolutely fascinating. Many brands across the cycling industry are waking up to the benefits of damping vibrations – whether its Spank putting Vibrocore into their rims and handlebars, OneUp engineering flex into theirs, RockShox putting ButterCups into suspension, RevGrips with their suspended grips, or indeed the vast array of tire inserts that also claim to reduce vibrations.

There is an increasing amount of innovation going on in this space, and it’s really cool to see. It’s interesting not only from a performance perspective, but also from a health perspective, too. Realistically, the vibrations we experience while mountain biking aren’t super kind to the immune system – as demonstrated by Dr Lewis Kirkwood, so anything that can be done to mitigate them without negatively impacting the joy of riding is a good thing.

Clearly, Rimpact still have work to do in proving the efficacy of their Tuned Mass Damper. We’ll be staying in touch to follow its development, and hope to bolt one onto our own bike over the coming months for some blinded back-to-back testing. Stay tuned, folks!

Editor’s Note: Readers keen to learn more about how mass dampers work to reduce maximum amplitude and to mitigate vibrations within a system, I point you in the direction of this peer-reviewed research article, an article that Matt himself digested during his own learning journey toward development of the Rimpact Tuned Mass Damper.

rimpactmtb.com

Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

36 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
Matt Shearn
1 year ago

So cool to talk to Jessie-May about this project after researching and developing it for so long. If you have any follow up questions about this article be sure to leave a comment and we will try and answer it when we can!

– Rimpact Team

sxp
sxp
1 year ago
Reply to  Matt Shearn

It’d be interesting to see how one of these would work in a seat tube, or mounted horizontally in a handlebar.

Anthony Barnes
Anthony Barnes
1 year ago
Reply to  sxp

I developed something similar 30 years ago called a JarBar. Hawked it around at some bike shows and still using an updated version today. Very good at absorbing high frequency oscillations an reinvesting forward energy;),

Matt Shearn
1 year ago
Reply to  Anthony Barnes

Interesting! Mass dampers are an engineering staple so I’m not suprise to hear this. Send us an email, I’d love to see your version and discuss what we’ve both leanred!

Matt Shearn
1 year ago
Reply to  sxp

So are we. Baby steps though. We need to make sure this definitively works firt before spending more resources on development.

Jack77
Jack77
1 year ago
Reply to  Matt Shearn

Are you thinking of progressive coil springs? A mass damper seems like an ideal application for progressive springs. (contrary to classical suspension)

Matt Shearn
1 year ago
Reply to  Jack77

Absolutely, it’s on the cards for future testing as we’ve seen a benefit of the lower rate springs on more chattery terrain and a benefit of higher rate springs on chunkier trails so the possibility of combining these in one package would be great.

Onawalk
Onawalk
1 year ago
Reply to  Matt Shearn

Quite interested,
‘couple questions.
have you come up with a way to damp the dampers movements?
does it have much of an effect while climbing on technical terrain?
how does the blind test work, how are your riders trying it with their eyes covered…..
honestly, if the damper is in a tube, essentially a shake weight in your head tube, how are they swapping back to back without knowing which is which?
id love to give it a try, and provide feedback, willing to pay you for one, along with shipping, just to test it for you.

Matt Shearn
1 year ago
Reply to  Onawalk

We’ve conducted tests with damper fluid and a modified design from the one shown in the article. Currently the prototype we are yeilding best results with however uses air friction to damp the system thanks to it’s sealed design and high tolerance of machining of the mass and outer case. The pictures in the article don’t show the outer case to internals tolerence. We will come back around to damper fluid once we’ve pushed the current design as far as it can go but for now, we are following results.

The blind test works by having two identical units that weigh the same and have no visible components. The images look like the mass is loosely suspended between the springs which is deceiving as it actually takes considerable force to push past the high resistance of the springs. This is how we are achieving a system that operates in the correct Hz range, if it was too light a spring rate the mass would simply bottom out on smaller movements and feel like I suspect most people are imagining when they see the images. To be clear, I can’t quite bottom out the spring when holding the mass and pressing down on it with my hands. As such, unless you shake the shake weight super hard, you can’t discern the difference. We were suprised to learn, after putting sensors on the bar, that the G forces were significantly higher than assumed, so when pluging this into a mathmatical formula for calculating a TMD functionality the spring rate requirement was increased. This then lead us down the path of a much ‘stiffer’ set up that began to yield results on the trail.

Johann
Johann
1 year ago

Haven’t all the intentions to fight vibrations appeared after the 35mm handlebars were “invented”? I think so. Coincidence? I think not.
More seriously this one is interesting and I am very curious to see how it translates in feel on trails.

Matt Shearn
1 year ago
Reply to  Johann

In some respects yes. I run 31.8mm alu bars and don’t specifically ‘suffer’ from vibration. But that said, smooth is fast. So if this makes me ride faster despite having high end suspension, vibration damping inserts and not particularly suffering from vibration through my hands, I think it’s pertinent to explore this further.

Ry Dude
Ry Dude
1 year ago

The human is the mass damper on a bicycle.

Matt Shearn
1 year ago
Reply to  Ry Dude

It is. And yet I still crash 😀

neil100
neil100
1 year ago

Sounds similar in concept to the Bontrager BuzzKill bar plugs but perhaps more impactful for mountain bikes with a larger mass?

Matt Shearn
1 year ago
Reply to  neil100

The Bzzzkill is a harmonic damper, akin to the handfull you’ll have attached to your car to prevent the engine vibration rattling it apart. It sets out to achieve similar goals of cancelling oscilations but in a lower tech way. It won’t reduce total amplitude of force however and instead act primarily as a ‘deadner’, where as a SDoF damper has multiple capabilities in practice.

Tim Tucker
Tim Tucker
1 year ago

While this is essentially dead weight, I wonder if there’s opportunity for refinement in having the mass be something that’s actually needed.

For example, having a water bottle or the battery in an e-bike mounted in a way that turns it into a mass damper.

Alternately, it makes me wonder just how much keeping an extra 30oz bottle of water in a handlebar bag is already acting as a damper on my bike.

Last edited 1 year ago by Tim Tucker
Onawalk
Onawalk
1 year ago
Reply to  Tim Tucker

That’s not how this works, that’s not how any of this works….
so you start off with a 2lb mass damper water bottle, with no way to control the movement of the fluid inside, and as you ride, you have a damper that is now lighter, and therefore less useful than when you started.
‘you’re on the right track here, strap a half dozen water bottles to your handlebar bag and report back

Tim Tucker
Tim Tucker
1 year ago
Reply to  Onawalk

What about a more consistent weight with more predictable movement like a pair of pruning shears for trail maintenance in a handlebar bag?

Now we’re at about $25 cost and if you use them it improves the riding experience for everyone on the trail, not just you.

Leigh
Leigh
1 year ago
Reply to  Tim Tucker

I think the pruning shears will be less predictable movement, but I agree on the usefulness of them.
You’ll really need to ensure that handlebar bag is quite sturdy, and for heavens sake, dont crash!

Fake Namerton
Fake Namerton
1 year ago

All this gimmickry and mountain bikes are still on antiquated damper rod forks anyway but cost 10 grand lol

Tom
Tom
1 year ago
Reply to  Fake Namerton

except that nobody has developed another concept that is demonstrably superior. So damper rods it is…

Fake Namerton
Fake Namerton
1 year ago
Reply to  Tom

Cartridge anti-cavitation forks have existed since the 80s.

nooner
nooner
1 year ago

@MattShearn, So what am I looking at here? Let’s say this was not a prototype, but a finished product to go into a FOX 38 fork. Would this go in series with the Grip2 damper? You’re not going to control compression and rebound with what I’m looking at here. This looks like it could help cancel or diminish high frequency spikes, similiar to RS buttercups. The elephant in the room is nobody understands what they are looking at here and I’m the only one to call you out.

Andrea Rearte
Andrea Rearte
1 year ago
Reply to  nooner

Tuned Mass dampers work in the way, that the movement of the tuned mass damper counteracts the vibrations of the thing you want to calm down. Think of it this way: In the ideal scenario, the mass moves towards the lower dead spot the same instance the object is moving towards the upper dead spot and thus creates an opposing force to the force that the object is creating.
For that, the weight and the spring have to be tuned to the harmonic frequency of that thing. A damper then dissipates the energy. If done correctly, you can kind of cut away the amplitudes of the ocurring vibration especially when the object starts to resonate (which tells me TMD’s might work better in road/gravel bikes because of the nature of input vibrations). The whole thing is quite complicated and i am not well versed in vibrations and resonance. But there is a lot of info in the interwebz.

Matt Shearn
1 year ago
Reply to  nooner

Andrea explained it well. The problem with your question is that you are viewing a “damper” in your fork as one and the same as the tuned mass “damper” but they are similar in name only, not in purpose or application. So your grip2 damper remains in place and slows the movement of oil through small holes and past flexible shims to change the rate in which your air spring can extend or compress. You’ll still need this as it’s how you make a “spring” feel good to ride on top of, you get grip from the tyre and your body weight is suspended in a controlled manner.

A TMD is not a spring/damper combo that you sit on top of. It is a device that counters movement and offsets it. In this instance it sits within the system (inside your hollow steer tube, not your stanchion) rather than as a connector between to components. When the system is displaced it lags behind the oscillation force and that lag is integral to how it counters that momentum. Whether or not it’s possible to tune this particular design to a place where it exerts enough change on the system that it provides a benefit is where we currently are in terms of testing.

nooner
nooner
1 year ago
Reply to  Matt Shearn

OK, now we are getting somewhere: “In this instance it (TMD) sits within the system (inside your hollow steer tube, not your stanchion)” Any pics or a diagram how this would acually work in practical application?

Matt Shearn
1 year ago
Reply to  nooner

Yep check our instagram for a reel of it being dropped into place (minus the lack of it being fixed in place by the compression washer/bolt).

Gilbert
Gilbert
1 year ago

I think the implications for this are twofold. Jounce control and fatigue reduction.
By controlling jounce, it’s possible to use more aggressive low speed valving and make it less jarring and possibly even complement tires like tacky chan that have more trail feedback.
As someone with carpal tunnel syndrome, the fatigue reduction aspect is of interest to me. 19% reduction in amplitude may not sound much but to put in into context, Rockshox claims 20% reduction on chatter for their Buttercups.

Matt Shearn
1 year ago
Reply to  Gilbert

Jounce – to Jolt and Bounce. Cracking descriptor.

Exactly. This overengineered prototype is garnering a lot of controversy yet some simple elastomer washers with radical claims was praised heavily 😀 (Disclaimer: Love the idea of Buttercups and would imagine they work great but haven’t tried them myself yet). There may, or may not, be a huge opportunity for all sorts of bikers hiding in plain sight with an adapted TMD for biking use. It’s a wasted opportunity not to explore it. The key here is we won’t sell it if we can’t prove beyond doubt that it works.

Gilbert
Gilbert
1 year ago
Reply to  Matt Shearn

Is there any chance that you might also experiment with the rear swing arm just like the TMDs found in motorcycles to prevent high sides and increase grip because stiff tires can be pingy and unpredictable. I don’t think it’s controversial at all since it’s logical to view suspension like an electric circuit where these act as inerters or capacitors. Might be a good idea to experiment with tire insert and TMD combos that give the least amount of overshoots and most amount of control since they both tune out tire jounce.

I think this might solve some problems for high pivot bikes that experience brake squat due to high anti-rise. I recall Trek using harmonic dampers for them.

I think Enduro riders would appreciate this tech to be honest given how much arm pump can be an issue. I mean, riders even use Axxios/Sniptec stickers just to squeeze every marginal comfort they can get.

Gilbert
Gilbert
1 year ago
Reply to  Matt Shearn

Also forgot, I think it would be better to use FFT for your graphs. We use them a lot for tuning FPV drone vibrations and tuning control authority. In as sense, TMDs would be on the Derivative of a PID loop since they are analogous to suspensions.

Maybe for future provide some bike + rider calculator to get the approximate suspended mass + spring combo. We want it tuned after all unlike some elastomers 🙂

Frank
Frank
1 year ago

The concept is not new to cycling, e.g. Time-Sport’s ‘AKTIV’ road forks with mass dampers hidden inside the fork legs. Videos can easily be found online.

marcus
marcus
1 year ago
Reply to  Frank

looks to be the same concept, but applied in a different way. The video of the aktiv demonstrator shows how this sort of thing works really well!

Mehta
Mehta
1 year ago

Looks like the Intrinsic damper Manitou used about 15+ years ago.

Guy
Guy
1 year ago

On the Citroën 2cv inertia shock absorbers 1949 was used.
http://www.citroenet.org.uk/passenger-cars/michelin/2cv/history/1949.html

GIHOSU
GIHOSU
2 months ago

I’d go for a prototype to test, they work on my faster R/C race cars and were outlawed by F1 so there’s something to them.

Subscribe Now

Sign up to receive BikeRumor content direct to your inbox.

Subscribe Now

Sign up to receive BikeRumor content direct to your inbox.