They're an honest company. The tech isn't expensive at all. As @TheSuspensionLabNZ noted, you could McGyver one with an Ohlins green spring, a 600g mass and a...
They're an honest company. The tech isn't expensive at all.
As @TheSuspensionLabNZ noted, you could McGyver one with an Ohlins green spring, a 600g mass and a tube and some rubber for vibrations, forget a mountain bracket just zip tie that sucker on.
Charging $500 just means someone else will move in and undercut you and make you look like an idiot and lose all sales.
There's a lot more to the CounterShox than going to a hardware store and picking up parts. Think about the millions of combinations of springs and...
There's a lot more to the CounterShox than going to a hardware store and picking up parts. Think about the millions of combinations of springs and weights, rattle noises, fork mounts, ect. I suspect there's more going on with their product than springs and weights.
I've tried it on a motocross bike and DH bike and was really surprised/happy with the results. I think the price isn't for everyone and the added weight isn't for everyone. I bought them because I'm interested in trying new parts, but it's going to be hard to ride without them now.
The only part of your bike thats truly unsuspended is the contact patch of your tires, so putting one of these puppies literally anywhere else can yield benefits in different ways.
They have been used successfully for years in Moto.
My question is whats the difference between this and just added weights? Mass simply attached to the frame will reduce vibrations and make suspension work at a wider range of frequencies.
Finally, I first proposed in the main tech rumors channel that you could reuse the weight of ebike components for something like this (it also proves that added mass alone makes a big difference in ride quality). Imagine a battery with 2-3 mm of suspended movement in several different axis.
So TLDR: The only part of your bike thats truly unsuspended is the contact patch of your tires, so putting one of these puppies literally anywhere else...
So TLDR:
The only part of your bike thats truly unsuspended is the contact patch of your tires, so putting one of these puppies literally anywhere else can yield benefits in different ways.
They have been used successfully for years in Moto.
My question is whats the difference between this and just added weights? Mass simply attached to the frame will reduce vibrations and make suspension work at a wider range of frequencies.
Finally, I first proposed in the main tech rumors channel that you could reuse the weight of ebike components for something like this (it also proves that added mass alone makes a big difference in ride quality). Imagine a battery with 2-3 mm of suspended movement in several different axis.
I filmed some video of my sketchy TMD attached to just a wheel this morning. Specfically tested it with the weights still attached but deactivated, as well as different amounts of weight and different tyre pressure. And yeah it makes a huuuuge difference having the correctly tuned TMD vs just adding weight. Just got to stitch the clips together and I'll post them up
And yes the tyre contact patch is the only "true" unsprung mass - not to say controlling the wheel relative to the frame isn't important, but its ideal if you can reduce unnecessary vibration from transmitting that far. You can still using a device on the bike of some sort but it won't be able to control those tiny high frequency fluctuations at the tyre
This is one thing I’ve been wondering about. To get say 1lb to have a natural frequency in the realm of braking bumps you need stupidly...
This is one thing I’ve been wondering about. To get say 1lb to have a natural frequency in the realm of braking bumps you need stupidly stiff springs. So stiff they are a little hard to find with meaningful amounts of deflection.
Just give your weight "HBO" pistons on either side. 🤪
I tried to get some info out of Dak when we podcasted yesterday, but he was pretty tight lipped about everything. He still gave some insight into why he is running a TMD on the swingarm. It also sounds like he'll be adding one to his fork in the future.
Counterscycle for MTB is up on their website, sadly not a lot of info there. Thinking of pulling the trigger on one, even while sitting on the other side of the pond…
It’s already in his fork… has anyone said that already? He said they’ve been hidden in bikes for some time and the way he said “if” he had a second sounds like yeah there is a second you just can’t see it. Probably the exact unit that’s in the fork bolts on to the rear. Looks to be the right diameter to fit in a fork…
It’s already in his fork… has anyone said that already? He said they’ve been hidden in bikes for some time and the way he said “if”...
It’s already in his fork… has anyone said that already? He said they’ve been hidden in bikes for some time and the way he said “if” he had a second sounds like yeah there is a second you just can’t see it. Probably the exact unit that’s in the fork bolts on to the rear. Looks to be the right diameter to fit in a fork…
Maybe inside the steerer tube, but I can‘t see where you could put in inside the fork, then you would have to take away a quite significant part from either the airspring or damper. How I understood him in the pod he really doesn‘t have a second one, and I think I saw a pic somewhere in the pit bits with one mounted to Ronan‘s fork, so if they had the tech inside the fork why would he have one on the outside.
It’s already in his fork… has anyone said that already? He said they’ve been hidden in bikes for some time and the way he said “if”...
It’s already in his fork… has anyone said that already? He said they’ve been hidden in bikes for some time and the way he said “if” he had a second sounds like yeah there is a second you just can’t see it. Probably the exact unit that’s in the fork bolts on to the rear. Looks to be the right diameter to fit in a fork…
If you put a tmd on the unsprung swingarm you could modulate the speed of the beginning of the compression and the beginning of the rebound. Dak seems to like damping and there is only so much you can control in the shock, but with an external device like this you could really fine tune initial stroke feel and how fast that rebound comes on. I guess this would totally change how the suspension feels as it’s rapidly cycling between compression and rebound, allowing for the shock and tmd to have different tunes to optimize for different forces? You could run super fast rebound and a slightly lighter compression tune where the tmd could provide a bit of control/calming at the front of compression and at the front of rebound… I dunno is this making any sense?
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and 26psi, the 18psi gave the best result. Using parts on hand like some springs around 11.8 N/mm, a 250g mass and a 600g(250+350) mass. (*edit using the 2 opposing springs halves the rate so more like 6 N/mm) The wheel alone is about 1800g so total system about 2.4kg
Tyre rates are roughly 35N/mm @ 18psi and 44N/mm at 26psi BUT they are slightly progressive in the first few mm plus I trimmed the knobs off as they made the first few mm even softer again. So the actual rates are probably lower but that gives a natural frequencya bit under 20Hz at 18psi and 22hz at 26
The 250g mass TMD is roughly 25Hz and the 600g mass about 16Hz. The lighter mass @ 25Hz had barely any effect but the 16Hz damped out the bounce super quickly! At 26psi the bounces were less but not quite as effective as at 18psi. My numbers were worked out pretty roughly and things like the tyre rates are hard to get accurate for such small displacement tests, so will try some more weight/lower frequency next time around but the effect is pretty clear IMO.
*edit - something wasn't adding up with my calculations and results in my head, and figured out it was due to the 2 opposing springs on the TMD effectively halves the rate which lowers the natural frequency (not by half, but enough to make the outcome more consistent with what I expected)
Im not even going to read the write up. Is this like adding a shake weight to the rear of my bike? Ok, so after thinking...
Im not even going to read the write up. Is this like adding a shake weight to the rear of my bike?
Ok, so after thinking about this a bit more (im not an engineer, my job is essentially playing with crayons) I would imagine that Loris's setup is much better than the mondraker one? Having something be on the complete back end of your bike would really mess with your rear shock.... right?
Ah crap read the other thread and I'm not even original. Lots of shake weight comments allready.
I am not an expert by any means and haven’t read everything that others have said. However I wonder if it is to control oscillation coming from the wheel its self in which case the placement would be ideal.
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and...
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and 26psi, the 18psi gave the best result. Using parts on hand like some springs around 11.8 N/mm, a 250g mass and a 600g(250+350) mass. (*edit using the 2 opposing springs halves the rate so more like 6 N/mm) The wheel alone is about 1800g so total system about 2.4kg
Tyre rates are roughly 35N/mm @ 18psi and 44N/mm at 26psi BUT they are slightly progressive in the first few mm plus I trimmed the knobs off as they made the first few mm even softer again. So the actual rates are probably lower but that gives a natural frequencya bit under 20Hz at 18psi and 22hz at 26
The 250g mass TMD is roughly 25Hz and the 600g mass about 16Hz. The lighter mass @ 25Hz had barely any effect but the 16Hz damped out the bounce super quickly! At 26psi the bounces were less but not quite as effective as at 18psi. My numbers were worked out pretty roughly and things like the tyre rates are hard to get accurate for such small displacement tests, so will try some more weight/lower frequency next time around but the effect is pretty clear IMO.
*edit - something wasn't adding up with my calculations and results in my head, and figured out it was due to the 2 opposing springs on the TMD effectively halves the rate which lowers the natural frequency (not by half, but enough to make the outcome more consistent with what I expected)
Awesome work mate! Love the video comparison
I was reading more on Tapei 101, and this is exactly how their TMD works. Its really actually quite simple when you think of it conceptually as the mass is just absorbing energy by moving a lot, meaning the body moves less. (watch how much the weight on the right tyre moves in absolute values, i.e add up all the upwards movement and downwards movement together).
Now were onto the interesting part, what does the rider feel when adding it to the frame, vs sprung mass?
I still cant figure out a big part of the system though is that a bike is somewhat like a reverse pendulum as the rider can also weight and absorb force through arms and legs, and how the total system interacts.
Awesome work mate! Love the video comparisonI was reading more on Tapei 101, and this is exactly how their TMD works. Its really actually quite simple...
Awesome work mate! Love the video comparison
I was reading more on Tapei 101, and this is exactly how their TMD works. Its really actually quite simple when you think of it conceptually as the mass is just absorbing energy by moving a lot, meaning the body moves less. (watch how much the weight on the right tyre moves in absolute values, i.e add up all the upwards movement and downwards movement together).
Now were onto the interesting part, what does the rider feel when adding it to the frame, vs sprung mass?
I still cant figure out a big part of the system though is that a bike is somewhat like a reverse pendulum as the rider can also weight and absorb force through arms and legs, and how the total system interacts.
Yup thats why I think a frame mounted TMD would be much harder to implement as the weight distribution changes a lot and the rider can absorb those transient movements anyway (unless you had a big mass on the rider like that backpack!). If you looked at the bike as a seperate system on its own you could come up with a way to absorb vibration with a TMD, but the maths would be a bit trickier and much more variable between frames and riders
So I watched Jason’s discussion with Dak on these and understandably he’s being a bit cagey (and possibly doesn’t actually know much about them besides that they make him faster haha). Luckily, Fox Factory’s patent application pretty much lays out exactly what the potential benefits are.
If mounted on the unsprung mass (like we saw on Dak’s bike last weekend), the TMD can serve to improve the tire’s contact with the ground. This is more or less what SuspensionLabNZ’s video demo above is demonstrating – awesome work on that btw.
If mounted on the sprung mass, it seems like it would likely serve more to reduce rider experienced vibrations. See what Countershox is doing as an example.
Fox’s application goes a bit beyond what’s I’ve seen discussed here actually, as it in part focuses on ways to dynamically adjust the spring rate and/or damping of the TMD to react to the actual biker/rider system by way of sensors. (That’s pretty much exactly the novelty what I was imagining when I first started seeing pics and discussion of these, so that’s pretty solid confirmation that the big dogs are already working on this and I should just leave it to them.)
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires down and let the sidewalls do their work. It would also damp the tire rebound as well?!?
But the thing is, with a damped setup the springs and dampers currently suspending the tyres already achieve a lot of what a TMD does.
Drop a fully rigid bike onto the ground, now drop a DH bike, it already bounces less, and that's exactly what suspension is for (it's just over sprung as there isn't the rider mass, just the frame mass).
But if you tune the suspension to JUST the frame weight, you can achieve exactly what @TheSuspensionLabNZ got in his test above.
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires...
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires down and let the sidewalls do their work. It would also damp the tire rebound as well?!?
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce higher than the size of the bump, which will unload the tyre more and you lose grip. Without it there are 2 possibilites -
The bump is too fast for the suspension to react - so is transmitted to the rider
The suspension does absorb it, but the damper speeds are higher, which equals more compression damping forces and more feedback to the rider. The tyre still unweights more than you want it too and you have reduced grip
While its maybe "resisting" the beginning of the stroke - that doesn't matter, as long as the tyre stays stuck to the ground its a good thing to make the suspension work less!
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires...
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires down and let the sidewalls do their work. It would also damp the tire rebound as well?!?
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce...
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce higher than the size of the bump, which will unload the tyre more and you lose grip. Without it there are 2 possibilites -
The bump is too fast for the suspension to react - so is transmitted to the rider
The suspension does absorb it, but the damper speeds are higher, which equals more compression damping forces and more feedback to the rider. The tyre still unweights more than you want it too and you have reduced grip
While its maybe "resisting" the beginning of the stroke - that doesn't matter, as long as the tyre stays stuck to the ground its a good thing to make the suspension work less!
Yes absolutely. As soon as I saw your vids it clicked!
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires...
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires down and let the sidewalls do their work. It would also damp the tire rebound as well?!?
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce...
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce higher than the size of the bump, which will unload the tyre more and you lose grip. Without it there are 2 possibilites -
The bump is too fast for the suspension to react - so is transmitted to the rider
The suspension does absorb it, but the damper speeds are higher, which equals more compression damping forces and more feedback to the rider. The tyre still unweights more than you want it too and you have reduced grip
While its maybe "resisting" the beginning of the stroke - that doesn't matter, as long as the tyre stays stuck to the ground its a good thing to make the suspension work less!
Also, I would assume that putting the damper before any linkage assembly means the damper is more effective. You aren’t depending on the linkage to faithfully transmit these small bumps to the shock, where they might instead be lost to friction or general inefficiency/anti-squat/whatever else is happening along the way. A lot of the vibration and force is probably not always even getting to the shock, but instead being sent through the frame. If you can limit how much that unsprung mass moves on this smaller scale you can probably cut out a ton of noise from the system.
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires...
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires down and let the sidewalls do their work. It would also damp the tire rebound as well?!?
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce...
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce higher than the size of the bump, which will unload the tyre more and you lose grip. Without it there are 2 possibilites -
The bump is too fast for the suspension to react - so is transmitted to the rider
The suspension does absorb it, but the damper speeds are higher, which equals more compression damping forces and more feedback to the rider. The tyre still unweights more than you want it too and you have reduced grip
While its maybe "resisting" the beginning of the stroke - that doesn't matter, as long as the tyre stays stuck to the ground its a good thing to make the suspension work less!
Also, I would assume that putting the damper before any linkage assembly means the damper is more effective. You aren’t depending on the linkage to faithfully...
Also, I would assume that putting the damper before any linkage assembly means the damper is more effective. You aren’t depending on the linkage to faithfully transmit these small bumps to the shock, where they might instead be lost to friction or general inefficiency/anti-squat/whatever else is happening along the way. A lot of the vibration and force is probably not always even getting to the shock, but instead being sent through the frame. If you can limit how much that unsprung mass moves on this smaller scale you can probably cut out a ton of noise from the system.
Yup thats exactly it - I've read a few papers about modelling car suspension systems, and friction in the linkages cause the biggest problems with correlating model data and shaker rig tests, where they measure the acceleration at several points in the chain
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and...
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and 26psi, the 18psi gave the best result. Using parts on hand like some springs around 11.8 N/mm, a 250g mass and a 600g(250+350) mass. (*edit using the 2 opposing springs halves the rate so more like 6 N/mm) The wheel alone is about 1800g so total system about 2.4kg
Tyre rates are roughly 35N/mm @ 18psi and 44N/mm at 26psi BUT they are slightly progressive in the first few mm plus I trimmed the knobs off as they made the first few mm even softer again. So the actual rates are probably lower but that gives a natural frequencya bit under 20Hz at 18psi and 22hz at 26
The 250g mass TMD is roughly 25Hz and the 600g mass about 16Hz. The lighter mass @ 25Hz had barely any effect but the 16Hz damped out the bounce super quickly! At 26psi the bounces were less but not quite as effective as at 18psi. My numbers were worked out pretty roughly and things like the tyre rates are hard to get accurate for such small displacement tests, so will try some more weight/lower frequency next time around but the effect is pretty clear IMO.
*edit - something wasn't adding up with my calculations and results in my head, and figured out it was due to the 2 opposing springs on the TMD effectively halves the rate which lowers the natural frequency (not by half, but enough to make the outcome more consistent with what I expected)
This video is awesome and you did it so quick in response to this thread!
I’ve been using the CounterShox that was designed for moto (about 2 lb) and I’ve found that I can use it in a way to dampen small chatter like washboard bumps and sharp square braking bumps/rocks. Say something that is less than 6inches in height.. With the countershox removing the feel of those bumps from my hands, I’m able to run my LSC slightly stiffer and my HSC much stiffer than normal. This is giving me a more chassis stability and less pitching on and off brakes. Also the big single hits like front wheel into a hole or off a rock into the flats aren’t blowing through the travel because I’m now stiffer HSC.
The point I’m trying to make is that if you mount to chassis or mount to axle it’s going to dampen some feel or vibration but in a different way. Either route you can use this in conjunction with you fork, shock, frame compliance to give you the most comfortable ride.
Your video shows that it works, there’s something to this. I think the question is how to package the device, what frequency and how do you now set up your suspension when using it.
Awesome work mate! Love the video comparisonI was reading more on Tapei 101, and this is exactly how their TMD works. Its really actually quite simple...
Awesome work mate! Love the video comparison
I was reading more on Tapei 101, and this is exactly how their TMD works. Its really actually quite simple when you think of it conceptually as the mass is just absorbing energy by moving a lot, meaning the body moves less. (watch how much the weight on the right tyre moves in absolute values, i.e add up all the upwards movement and downwards movement together).
Now were onto the interesting part, what does the rider feel when adding it to the frame, vs sprung mass?
I still cant figure out a big part of the system though is that a bike is somewhat like a reverse pendulum as the rider can also weight and absorb force through arms and legs, and how the total system interacts.
Yup thats why I think a frame mounted TMD would be much harder to implement as the weight distribution changes a lot and the rider can...
Yup thats why I think a frame mounted TMD would be much harder to implement as the weight distribution changes a lot and the rider can absorb those transient movements anyway (unless you had a big mass on the rider like that backpack!). If you looked at the bike as a seperate system on its own you could come up with a way to absorb vibration with a TMD, but the maths would be a bit trickier and much more variable between frames and riders
(preface this by saying superb work on the video, love seeing some actual applied science being done!)
In the podcast Dak suggested that TMDs were primarily being mounted to frames to eliminate higher frequency vibrations to aid in rider comfort - and I don't think this is meant in a trivial sense, it's genuinely something that can help the rider at high speeds. To paraphrase him "the speeds that we're going at your eyeballs start to rattle in your skull".
I don't disagree that the mobile nature of the riders mass will have a large impact on certain natural frequencies (I guess the lower ones), but all structures will have multiple modes of deformation with their own natural frequencies that excite a lower or higher percentage of the mass of the structure. Generally designers only care about the first and lowest frequency mode that excites the largest percentage of the mass, but that doesn't mean there aren't other modal frequencies that are having an impact on the rider.
I'm fairly certain the TMDs being strapped to frames are an attempt to reduce the accelerations/mass participation factors in those higher frequency modes. As carolinojoevideo points out with his, it makes a difference on the washboardy/chattery stuff.
As you've very elegantly demonstrated, placing a TMD on a wheel axle is a very different purpose and is about reducing the acceleration due to wheel rebound. Dak suggested the intent is increasing grip and calming the ride down. Perhaps the inherent friction in all shock seals prevents them from being able to react fast enough to effectively damp super high frequency oscillations, and this is what the mondraker guys are concerned with as they've identified they can impact grip? And maybe the overall effect is much more pronounced at the rear wheel due to the leverage it has on the shock via the linkage and the mass transfer of the rider as the axle moves along it's path through the travel? Interested to see where this all leads.
Maybe an unpopular opinion but my feelings on inserts, o-chain, tmd...
Not saying they don't work or there isn't a benefit, but have we really exhausted improvements to the underlying system yet? Only two teams have a gearbox, are DH tires and wheels really as light as they could be, no other team has suspension that looks as good as specialized, etc, etc...
Maybe an unpopular opinion but my feelings on inserts, o-chain, tmd...Not saying they don't work or there isn't a benefit, but have we really exhausted improvements...
Maybe an unpopular opinion but my feelings on inserts, o-chain, tmd...
Not saying they don't work or there isn't a benefit, but have we really exhausted improvements to the underlying system yet? Only two teams have a gearbox, are DH tires and wheels really as light as they could be, no other team has suspension that looks as good as specialized, etc, etc...
$$$. Sponsors pay big bucks, and so teams will be limited to how those companies want to play with their components. Drivetrains are the biggest impacted here. With all the improvements in carbon and alloy and rim construction people stick with classics, and I’m assuming good reason?
I’m also curious about your phrasing of “underlying system.” The system is interconnnected and there is a lot to be gained from these smaller parts that will have benefits across that system. The TMD will keep the tires on the ground which will make them work better and will also probably lead to changes in tire design (as the TMD will lead to a very different “casing feel” and increased traction could lead to changes in tread design preferences…) ochain seems small but can free up suspension design in that some undesirable forces can be kept out of the riders feet.
It might seem overwhelming that so many weird little details are being obsessed over and integrated, but these are part of the true underlying system that you’re alluding to, a system of seemingly disparate elements that add up to a very different feeling and performing bicycle.
Dak mentioned using the TMD differently in Andorra versus how he thought he might use it in Loudenvielle. And maybe the SuspensionLabNZ video shows us that the TMD helps with tire bounce more when the tire is at a higher pressure. Andorra was a very fast track, so maybe they were trying to use the TMD to allow them to run higher pressures for better rolling resistance, while the TMD helped to calm down the bouncing of the tire over the chatter.
Someone can maybe say that more eloquently...higher speeds, more chatter, wants higher tire psi to roll faster, it starts feeling rough, TMD calms it back down, win-win
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and...
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and 26psi, the 18psi gave the best result. Using parts on hand like some springs around 11.8 N/mm, a 250g mass and a 600g(250+350) mass. (*edit using the 2 opposing springs halves the rate so more like 6 N/mm) The wheel alone is about 1800g so total system about 2.4kg
Tyre rates are roughly 35N/mm @ 18psi and 44N/mm at 26psi BUT they are slightly progressive in the first few mm plus I trimmed the knobs off as they made the first few mm even softer again. So the actual rates are probably lower but that gives a natural frequencya bit under 20Hz at 18psi and 22hz at 26
The 250g mass TMD is roughly 25Hz and the 600g mass about 16Hz. The lighter mass @ 25Hz had barely any effect but the 16Hz damped out the bounce super quickly! At 26psi the bounces were less but not quite as effective as at 18psi. My numbers were worked out pretty roughly and things like the tyre rates are hard to get accurate for such small displacement tests, so will try some more weight/lower frequency next time around but the effect is pretty clear IMO.
*edit - something wasn't adding up with my calculations and results in my head, and figured out it was due to the 2 opposing springs on the TMD effectively halves the rate which lowers the natural frequency (not by half, but enough to make the outcome more consistent with what I expected)
This video is awesome and you did it so quick in response to this thread!I’ve been using the CounterShox that was designed for moto (about 2...
This video is awesome and you did it so quick in response to this thread!
I’ve been using the CounterShox that was designed for moto (about 2 lb) and I’ve found that I can use it in a way to dampen small chatter like washboard bumps and sharp square braking bumps/rocks. Say something that is less than 6inches in height.. With the countershox removing the feel of those bumps from my hands, I’m able to run my LSC slightly stiffer and my HSC much stiffer than normal. This is giving me a more chassis stability and less pitching on and off brakes. Also the big single hits like front wheel into a hole or off a rock into the flats aren’t blowing through the travel because I’m now stiffer HSC.
The point I’m trying to make is that if you mount to chassis or mount to axle it’s going to dampen some feel or vibration but in a different way. Either route you can use this in conjunction with you fork, shock, frame compliance to give you the most comfortable ride.
Your video shows that it works, there’s something to this. I think the question is how to package the device, what frequency and how do you now set up your suspension when using it.
Yup that makes sense - I can picture the frame mounted system working that way, like proper bumps which would normally upset the bike, where as teh hub mounted ones deal with small corrugations that the suspension would normally struggle to react to. Each quite separate types of bumps so should be able to work together in the same bike.
*also I edited some of the notes on that video - something wasn't correlating properly with the maths and I realised it was because I calculated the frequency of the TMD using a single spring but having 2 opposing springs effectively halves the rate. Doesn't halve the frequency but lowers it enough to make the outcome more in line with what the maths says
(preface this by saying superb work on the video, love seeing some actual applied science being done!)In the podcast Dak suggested that TMDs were primarily being...
(preface this by saying superb work on the video, love seeing some actual applied science being done!)
In the podcast Dak suggested that TMDs were primarily being mounted to frames to eliminate higher frequency vibrations to aid in rider comfort - and I don't think this is meant in a trivial sense, it's genuinely something that can help the rider at high speeds. To paraphrase him "the speeds that we're going at your eyeballs start to rattle in your skull".
I don't disagree that the mobile nature of the riders mass will have a large impact on certain natural frequencies (I guess the lower ones), but all structures will have multiple modes of deformation with their own natural frequencies that excite a lower or higher percentage of the mass of the structure. Generally designers only care about the first and lowest frequency mode that excites the largest percentage of the mass, but that doesn't mean there aren't other modal frequencies that are having an impact on the rider.
I'm fairly certain the TMDs being strapped to frames are an attempt to reduce the accelerations/mass participation factors in those higher frequency modes. As carolinojoevideo points out with his, it makes a difference on the washboardy/chattery stuff.
As you've very elegantly demonstrated, placing a TMD on a wheel axle is a very different purpose and is about reducing the acceleration due to wheel rebound. Dak suggested the intent is increasing grip and calming the ride down. Perhaps the inherent friction in all shock seals prevents them from being able to react fast enough to effectively damp super high frequency oscillations, and this is what the mondraker guys are concerned with as they've identified they can impact grip? And maybe the overall effect is much more pronounced at the rear wheel due to the leverage it has on the shock via the linkage and the mass transfer of the rider as the axle moves along it's path through the travel? Interested to see where this all leads.
Yes on that last part - basically there is a lot of inertia and friction in the wheel and swingarm so getting it to move out of the way very quickly is a big ask. Soaking up that movement at the source is a much better way to deal with it
Yup that makes sense - I can picture the frame mounted system working that way, like proper bumps which would normally upset the bike, where as...
Yup that makes sense - I can picture the frame mounted system working that way, like proper bumps which would normally upset the bike, where as teh hub mounted ones deal with small corrugations that the suspension would normally struggle to react to. Each quite separate types of bumps so should be able to work together in the same bike.
*also I edited some of the notes on that video - something wasn't correlating properly with the maths and I realised it was because I calculated the frequency of the TMD using a single spring but having 2 opposing springs effectively halves the rate. Doesn't halve the frequency but lowers it enough to make the outcome more in line with what the maths says
Two opposing springs doubles the effective rate if I'm not mistaken. Since they experience the same displacement they are springs in parallel. If both springs are preloaded the same amount x1 and have the same rate k, then the combined force on the mass is (k(x1)+kx)-(k(x1)-kx). Preload cancels out and the force on the mass is 2kx. So that would put 600 g at about 32 Hz
Yup that makes sense - I can picture the frame mounted system working that way, like proper bumps which would normally upset the bike, where as...
Yup that makes sense - I can picture the frame mounted system working that way, like proper bumps which would normally upset the bike, where as teh hub mounted ones deal with small corrugations that the suspension would normally struggle to react to. Each quite separate types of bumps so should be able to work together in the same bike.
*also I edited some of the notes on that video - something wasn't correlating properly with the maths and I realised it was because I calculated the frequency of the TMD using a single spring but having 2 opposing springs effectively halves the rate. Doesn't halve the frequency but lowers it enough to make the outcome more in line with what the maths says
Two opposing springs doubles the effective rate if I'm not mistaken. Since they experience the same displacement they are springs in parallel. If both springs are...
Two opposing springs doubles the effective rate if I'm not mistaken. Since they experience the same displacement they are springs in parallel. If both springs are preloaded the same amount x1 and have the same rate k, then the combined force on the mass is (k(x1)+kx)-(k(x1)-kx). Preload cancels out and the force on the mass is 2kx. So that would put 600 g at about 32 Hz
Um, I know you know your stuff..But can u put that into English for dumb bike store owners...lol.
Yes for sure. I guess that’s were patients come into play on a product like this. We will see where they land along with Fox electronic tmd idea.
So TLDR:
The only part of your bike thats truly unsuspended is the contact patch of your tires, so putting one of these puppies literally anywhere else can yield benefits in different ways.
They have been used successfully for years in Moto.
My question is whats the difference between this and just added weights? Mass simply attached to the frame will reduce vibrations and make suspension work at a wider range of frequencies.
Finally, I first proposed in the main tech rumors channel that you could reuse the weight of ebike components for something like this (it also proves that added mass alone makes a big difference in ride quality). Imagine a battery with 2-3 mm of suspended movement in several different axis.
I filmed some video of my sketchy TMD attached to just a wheel this morning. Specfically tested it with the weights still attached but deactivated, as well as different amounts of weight and different tyre pressure. And yeah it makes a huuuuge difference having the correctly tuned TMD vs just adding weight. Just got to stitch the clips together and I'll post them up
And yes the tyre contact patch is the only "true" unsprung mass - not to say controlling the wheel relative to the frame isn't important, but its ideal if you can reduce unnecessary vibration from transmitting that far. You can still using a device on the bike of some sort but it won't be able to control those tiny high frequency fluctuations at the tyre
Just give your weight "HBO" pistons on either side. 🤪
I tried to get some info out of Dak when we podcasted yesterday, but he was pretty tight lipped about everything. He still gave some insight into why he is running a TMD on the swingarm. It also sounds like he'll be adding one to his fork in the future.
https://countershox.com/shop-2/
Counterscycle for MTB is up on their website, sadly not a lot of info there.
Thinking of pulling the trigger on one, even while sitting on the other side of the pond…
It’s already in his fork… has anyone said that already? He said they’ve been hidden in bikes for some time and the way he said “if” he had a second sounds like yeah there is a second you just can’t see it. Probably the exact unit that’s in the fork bolts on to the rear. Looks to be the right diameter to fit in a fork…
Maybe inside the steerer tube, but I can‘t see where you could put in inside the fork, then you would have to take away a quite significant part from either the airspring or damper.
How I understood him in the pod he really doesn‘t have a second one, and I think I saw a pic somewhere in the pit bits with one mounted to Ronan‘s fork, so if they had the tech inside the fork why would he have one on the outside.
If you put a tmd on the unsprung swingarm you could modulate the speed of the beginning of the compression and the beginning of the rebound. Dak seems to like damping and there is only so much you can control in the shock, but with an external device like this you could really fine tune initial stroke feel and how fast that rebound comes on. I guess this would totally change how the suspension feels as it’s rapidly cycling between compression and rebound, allowing for the shock and tmd to have different tunes to optimize for different forces? You could run super fast rebound and a slightly lighter compression tune where the tmd could provide a bit of control/calming at the front of compression and at the front of rebound… I dunno is this making any sense?
So it took me way to long to stitch these together and export it properly, but I did this test with the tyre at 18psi and 26psi, the 18psi gave the best result. Using parts on hand like some springs around 11.8 N/mm, a 250g mass and a 600g(250+350) mass. (*edit using the 2 opposing springs halves the rate so more like 6 N/mm) The wheel alone is about 1800g so total system about 2.4kg
Tyre rates are roughly 35N/mm @ 18psi and 44N/mm at 26psi BUT they are slightly progressive in the first few mm plus I trimmed the knobs off as they made the first few mm even softer again. So the actual rates are probably lower but that gives a natural frequencya bit under 20Hz at 18psi and 22hz at 26
The 250g mass TMD is roughly 25Hz and the 600g mass about 16Hz. The lighter mass @ 25Hz had barely any effect but the 16Hz damped out the bounce super quickly! At 26psi the bounces were less but not quite as effective as at 18psi. My numbers were worked out pretty roughly and things like the tyre rates are hard to get accurate for such small displacement tests, so will try some more weight/lower frequency next time around but the effect is pretty clear IMO.
*edit - something wasn't adding up with my calculations and results in my head, and figured out it was due to the 2 opposing springs on the TMD effectively halves the rate which lowers the natural frequency (not by half, but enough to make the outcome more consistent with what I expected)
I am not an expert by any means and haven’t read everything that others have said. However I wonder if it is to control oscillation coming from the wheel its self in which case the placement would be ideal.
Awesome work mate! Love the video comparison
I was reading more on Tapei 101, and this is exactly how their TMD works. Its really actually quite simple when you think of it conceptually as the mass is just absorbing energy by moving a lot, meaning the body moves less. (watch how much the weight on the right tyre moves in absolute values, i.e add up all the upwards movement and downwards movement together).
Now were onto the interesting part, what does the rider feel when adding it to the frame, vs sprung mass?
I still cant figure out a big part of the system though is that a bike is somewhat like a reverse pendulum as the rider can also weight and absorb force through arms and legs, and how the total system interacts.
Yup thats why I think a frame mounted TMD would be much harder to implement as the weight distribution changes a lot and the rider can absorb those transient movements anyway (unless you had a big mass on the rider like that backpack!). If you looked at the bike as a seperate system on its own you could come up with a way to absorb vibration with a TMD, but the maths would be a bit trickier and much more variable between frames and riders
So I watched Jason’s discussion with Dak on these and understandably he’s being a bit cagey (and possibly doesn’t actually know much about them besides that they make him faster haha). Luckily, Fox Factory’s patent application pretty much lays out exactly what the potential benefits are.
If mounted on the unsprung mass (like we saw on Dak’s bike last weekend), the TMD can serve to improve the tire’s contact with the ground. This is more or less what SuspensionLabNZ’s video demo above is demonstrating – awesome work on that btw.
If mounted on the sprung mass, it seems like it would likely serve more to reduce rider experienced vibrations. See what Countershox is doing as an example.
Fox’s application goes a bit beyond what’s I’ve seen discussed here actually, as it in part focuses on ways to dynamically adjust the spring rate and/or damping of the TMD to react to the actual biker/rider system by way of sensors. (That’s pretty much exactly the novelty what I was imagining when I first started seeing pics and discussion of these, so that’s pretty solid confirmation that the big dogs are already working on this and I should just leave it to them.)
Link for anyone interested. They kindly included detailed calculations for the super-nerds among us. TUNED MASS DAMPER - European Patent Office - EP 4403793 A1 (storage.googleapis.com)
I couldn’t figure out why you’d want more resistance at the beginning of the stroke but it seems like it’s just enough to keep the tires down and let the sidewalls do their work. It would also damp the tire rebound as well?!?
But the thing is, with a damped setup the springs and dampers currently suspending the tyres already achieve a lot of what a TMD does.
Drop a fully rigid bike onto the ground, now drop a DH bike, it already bounces less, and that's exactly what suspension is for (it's just over sprung as there isn't the rider mass, just the frame mass).
But if you tune the suspension to JUST the frame weight, you can achieve exactly what @TheSuspensionLabNZ got in his test above.
Yes its damping tyre rebound - I posted the transmissibilty plots earlier to try show how at a certain input frequency a sprung mass will bounce higher than the size of the bump, which will unload the tyre more and you lose grip. Without it there are 2 possibilites -
The bump is too fast for the suspension to react - so is transmitted to the rider
The suspension does absorb it, but the damper speeds are higher, which equals more compression damping forces and more feedback to the rider. The tyre still unweights more than you want it too and you have reduced grip
While its maybe "resisting" the beginning of the stroke - that doesn't matter, as long as the tyre stays stuck to the ground its a good thing to make the suspension work less!
Yes absolutely. As soon as I saw your vids it clicked!
Also, I would assume that putting the damper before any linkage assembly means the damper is more effective. You aren’t depending on the linkage to faithfully transmit these small bumps to the shock, where they might instead be lost to friction or general inefficiency/anti-squat/whatever else is happening along the way. A lot of the vibration and force is probably not always even getting to the shock, but instead being sent through the frame. If you can limit how much that unsprung mass moves on this smaller scale you can probably cut out a ton of noise from the system.
Yup thats exactly it - I've read a few papers about modelling car suspension systems, and friction in the linkages cause the biggest problems with correlating model data and shaker rig tests, where they measure the acceleration at several points in the chain
This video is awesome and you did it so quick in response to this thread!
I’ve been using the CounterShox that was designed for moto (about 2 lb) and I’ve found that I can use it in a way to dampen small chatter like washboard bumps and sharp square braking bumps/rocks. Say something that is less than 6inches in height.. With the countershox removing the feel of those bumps from my hands, I’m able to run my LSC slightly stiffer and my HSC much stiffer than normal. This is giving me a more chassis stability and less pitching on and off brakes. Also the big single hits like front wheel into a hole or off a rock into the flats aren’t blowing through the travel because I’m now stiffer HSC.
The point I’m trying to make is that if you mount to chassis or mount to axle it’s going to dampen some feel or vibration but in a different way. Either route you can use this in conjunction with you fork, shock, frame compliance to give you the most comfortable ride.
Your video shows that it works, there’s something to this. I think the question is how to package the device, what frequency and how do you now set up your suspension when using it.
(preface this by saying superb work on the video, love seeing some actual applied science being done!)
In the podcast Dak suggested that TMDs were primarily being mounted to frames to eliminate higher frequency vibrations to aid in rider comfort - and I don't think this is meant in a trivial sense, it's genuinely something that can help the rider at high speeds. To paraphrase him "the speeds that we're going at your eyeballs start to rattle in your skull".
I don't disagree that the mobile nature of the riders mass will have a large impact on certain natural frequencies (I guess the lower ones), but all structures will have multiple modes of deformation with their own natural frequencies that excite a lower or higher percentage of the mass of the structure. Generally designers only care about the first and lowest frequency mode that excites the largest percentage of the mass, but that doesn't mean there aren't other modal frequencies that are having an impact on the rider.
I'm fairly certain the TMDs being strapped to frames are an attempt to reduce the accelerations/mass participation factors in those higher frequency modes. As carolinojoevideo points out with his, it makes a difference on the washboardy/chattery stuff.
As you've very elegantly demonstrated, placing a TMD on a wheel axle is a very different purpose and is about reducing the acceleration due to wheel rebound. Dak suggested the intent is increasing grip and calming the ride down. Perhaps the inherent friction in all shock seals prevents them from being able to react fast enough to effectively damp super high frequency oscillations, and this is what the mondraker guys are concerned with as they've identified they can impact grip? And maybe the overall effect is much more pronounced at the rear wheel due to the leverage it has on the shock via the linkage and the mass transfer of the rider as the axle moves along it's path through the travel? Interested to see where this all leads.
Maybe an unpopular opinion but my feelings on inserts, o-chain, tmd...
Not saying they don't work or there isn't a benefit, but have we really exhausted improvements to the underlying system yet? Only two teams have a gearbox, are DH tires and wheels really as light as they could be, no other team has suspension that looks as good as specialized, etc, etc...
$$$. Sponsors pay big bucks, and so teams will be limited to how those companies want to play with their components. Drivetrains are the biggest impacted here. With all the improvements in carbon and alloy and rim construction people stick with classics, and I’m assuming good reason?
I’m also curious about your phrasing of “underlying system.” The system is interconnnected and there is a lot to be gained from these smaller parts that will have benefits across that system. The TMD will keep the tires on the ground which will make them work better and will also probably lead to changes in tire design (as the TMD will lead to a very different “casing feel” and increased traction could lead to changes in tread design preferences…) ochain seems small but can free up suspension design in that some undesirable forces can be kept out of the riders feet.
It might seem overwhelming that so many weird little details are being obsessed over and integrated, but these are part of the true underlying system that you’re alluding to, a system of seemingly disparate elements that add up to a very different feeling and performing bicycle.
Dak mentioned using the TMD differently in Andorra versus how he thought he might use it in Loudenvielle. And maybe the SuspensionLabNZ video shows us that the TMD helps with tire bounce more when the tire is at a higher pressure. Andorra was a very fast track, so maybe they were trying to use the TMD to allow them to run higher pressures for better rolling resistance, while the TMD helped to calm down the bouncing of the tire over the chatter.
Someone can maybe say that more eloquently...higher speeds, more chatter, wants higher tire psi to roll faster, it starts feeling rough, TMD calms it back down, win-win
Yup that makes sense - I can picture the frame mounted system working that way, like proper bumps which would normally upset the bike, where as teh hub mounted ones deal with small corrugations that the suspension would normally struggle to react to. Each quite separate types of bumps so should be able to work together in the same bike.
*also I edited some of the notes on that video - something wasn't correlating properly with the maths and I realised it was because I calculated the frequency of the TMD using a single spring but having 2 opposing springs effectively halves the rate. Doesn't halve the frequency but lowers it enough to make the outcome more in line with what the maths says
Yes on that last part - basically there is a lot of inertia and friction in the wheel and swingarm so getting it to move out of the way very quickly is a big ask. Soaking up that movement at the source is a much better way to deal with it
Two opposing springs doubles the effective rate if I'm not mistaken. Since they experience the same displacement they are springs in parallel. If both springs are preloaded the same amount x1 and have the same rate k, then the combined force on the mass is (k(x1)+kx)-(k(x1)-kx). Preload cancels out and the force on the mass is 2kx. So that would put 600 g at about 32 Hz
Um, I know you know your stuff..But can u put that into English for dumb bike store owners...lol.
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