Mass Dampers in MX?

Does it work on a fundamental level? Yes.

Does it make a difference on dirtbikes? I don't know. I've wanted to try one but they aren't cheap.

I read the info in their web site but still not understanding how it works.

So it has a similar effect as a steering damper?

Is it a spring mass damper inside there thats allowed to move along the long axis of the tube?

The principle is to use a mass inside the tube to counteract the forces felt by the rider. It goes on the forks as a method of reducing bar input pretty much. I dont know what a steering damper is.

Try this:

Stand up straight and hold your arm straight out in front of you.

Now, do a 'bicep curl' and make your arm 90* with it sill out front of you. Your hand should be near your face kinda.

In this position, shake your hand to and from your person fast. You should feel your core muscles engaging to keep your body stable.

Take your other hand and do the exact same thing but opposite of your other hand (when one goes away, one comes to). Your core will relax. You have satisfied Newtons third law.

Now... the mass damper for the dirtbike would undoubtedly need some tuning and sizing for certain bikes. There is no mention of this on the website.. something anyone would put on there if they had done the work - great marketing. So, I'm skeptical. I think it works, but how well is to be determined. If they knew, they would be boasting about it. In another thread about the kawi frame polishing the discussion entails how insanely mental riders can get and how placebo effects are huge in moto. I think that a device like this is probably 60-80% a mental pacifier for riders. I have a ton of "pacifiers" for riding that if not in place I tend to get in my head. I can see how this could be one.

The few offroad riders I know with them say it does make a difference it certain situations. Counterbalancer for the front end

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The inputs would be so vast and different i wouldnt imagine they could isolate some frequency and tune for it but full disclosure I think vibrations as a field is literal black magic and barely passed when i took it so... yeah.

Now, real life probably went something like "add weight til it feel good". Sometimes the steps between ideation and creation can be skipped and still have a great outcome as long as the person designing has a strong intuitive grasp on the concepts and mechanics behind the task. AKA gut feel engineering. Some of the best, and some of the worst. That's why I really would love to try one of these. Could be something special lol.

Kyle Lewis ran a mass damper outdoors in 2003. I've never seen an expert test of one. 

https://www.vitalmx.com/forums/For-Sale-Bazaar,26/SUSPENSION-EXPERTS-2003-era-looking-for-a-little-help-please-INERTIA-DAMPENER-tested-raced-by-Noleen,1378606 

Sure, why not add even more weight to a racing machine? It's not like they're even trying to keep them light anymore. 

Is this similar in principle to the thing some guys used to run on their swingarm?

Was going to mention this as well. I believe he (Kyle) liked it but it just never seemed to catch on.

Seems like if it’s movement is in the same axis as the fork, there isn’t much you can’t accomplish with the spring mass damper that is the forks already. 

First thing I thought of when I saw the installation video "So this is a shake weight for your forks. Weird" lol

I’m familiar with the concept of a tuned mass damper, having an engineering background (civil not mechanical, but still some general critical thinking overlap). That being said I can’t see how they’ve applied it as a one size fits all application without tuning options. Maybe it was through trials and testing and they found a setup that gave some improvement, and there could be even bigger gains through a system that can be tuned? I don’t know, the concept makes sense, but not sure on the application of it myself.

The biggest reason why it is difficult to make work on an MX bike as opposed to a race car is the bike is forced to lean to turn and the dampers affect is then significantly limited in  an MX application. Desert racers who are going more straight and trying to reduce shock from small bumps will se a noticeable result. MX bikes significantly less. Race car also try to limit body/car lean which is why they work in those applications as well.

I created countershox and would be happy to answer your questions. 

Kyle loaned me one of his spares to use at Budds Creek in 2002 and I thought it worked really well. It seemed to calm the kicking up of the rear in braking bumps and off a couple of the jumps that I didn't even realize I was getting until I tried the damper. 

I can definitely see the logic in your thought process. Truth be told. Probably 90% of the hard impacts that you hit are while  riding you are vertical butCountershox also does a great job Keeping the bike settled while turning enabling you to be able to stay in the rut without climbing the sidewalls and pushing wide.

It's really nothing like a steering damper. More like vertical stabilization 

What frequency is it tuned to?

Nate would you be interested in sending out a loaner for testing and an thorough review if I ship it both ways? zero cost to you. I'm so intrigued.

A very high frequency impact would be something in the range of 12-13 Hz . That would be something like a log or a rock. A low frequency impact would be something more like 2-3Hz. Those are the far ends of the spectrum but Most Impacts that You Encounter while riding are in the exact center of that range. For example breaking bumps are a direct result of the average frequency that created those bumps pushing the dirt into piles. So those are greatly attenuated. 

On a hard high frequency hit the the 1.5 pounds can Impact over 30 pounds. So if you had a 90 pound Impact coming through the bars you would only feel 60 of it.

This keeps being call a tuned mass damper but the true scientific definition doesn't have a bottoming component like the countershox has. That aspect of it makes it particularly advantageous In motocross. I hope that clears up some of the questions but feel free to ask more and I will try to be as clear as possible. Thank you 

Some weight Is beneficial for example linkage vs pds for mx