Um, I know you know your stuff..But can u put that into English for dumb bike store owners...lol.
When the mass slides one direction, the spring backing it in the direction it slides sees increase in force while the spring on the other side sees a decrease. If the spring rates are the same, the one spring force increases the same amount that the other spring force decreases. As a result, the net force is double what it would be with that displacement and a single spring.
A numeric example with easy numbers would be two springs with a 50 lb/in rate preloaded to 100 lbs each. When the mass is translated 1” to one side, one spring is now applying 150 lbs to the mass and the other is applying 50 lbs for a net force of 100 lbs. So in that 1” displacement the net force changes by 100 lbs which is a 100 lb/in effective spring rate.
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
Yeah I think you are right - I realised I hadn't thought that through enough and once I sat down to work through the numbers that seems to check out. I'll try work out some more precise numbers and repeat the test, hopefully find a TMD arrangement where the frequency is too high to work properly as well as too low. Maybe some potentiometers on the tyre & mass to see how much displacement each is going through as well....
Some dumb questions now that I'm catching up on this thread:
1. If the swingarm mounted TMD and the frame mounted TMD damp different frequencies (big impacts vs. tire bounce), would there be a benefit in running both simultaneously? Or would the two TMD's fight each other and you have a three-body problem?
2. Dak said there's hidden tech, and they're mounting their rear TMD to the rear axle. What if the hidden component is inside the fork, but mounted to the unsprung mass? It could be inside the fork lowers mounted at the bottom, as opposed to the sprung mass dampers we've seen from Countershox and Rimpact that are mounted to the top of the fork or in the steerer tube?
3. How long until someone in this thread buys a shakeweight and bolts it to their bike? Just a matter of time.
Some dumb questions now that I'm catching up on this thread:1. If the swingarm mounted TMD and the frame mounted TMD damp different frequencies (big impacts...
Some dumb questions now that I'm catching up on this thread:
1. If the swingarm mounted TMD and the frame mounted TMD damp different frequencies (big impacts vs. tire bounce), would there be a benefit in running both simultaneously? Or would the two TMD's fight each other and you have a three-body problem?
2. Dak said there's hidden tech, and they're mounting their rear TMD to the rear axle. What if the hidden component is inside the fork, but mounted to the unsprung mass? It could be inside the fork lowers mounted at the bottom, as opposed to the sprung mass dampers we've seen from Countershox and Rimpact that are mounted to the top of the fork or in the steerer tube?
3. How long until someone in this thread buys a shakeweight and bolts it to their bike? Just a matter of time.
I don’t see a reason why you couldn't mount to frame and axle besides asking yourself how much do you want your bike to weigh?
I had a Commencal V5 that was 43lb, session was 41lb with the same parts. I can’t really imagine adding more than 1-2lb to that.
I feel like Mondraker might be using one in steerer tube. But that limits the mount of weight and damping you can have. I don’t see how there would be room inside a fork upper/lower because you need room for the fork to compress into itself.
I did see this photo of Commencal testing something on the lower. Not sure if it’s Tmd or vorsprungs secus.
I don’t see a reason why you couldn't mount to frame and axle besides asking yourself how much do you want your bike to weigh? I had...
I don’t see a reason why you couldn't mount to frame and axle besides asking yourself how much do you want your bike to weigh?
I had a Commencal V5 that was 43lb, session was 41lb with the same parts. I can’t really imagine adding more than 1-2lb to that.
I feel like Mondraker might be using one in steerer tube. But that limits the mount of weight and damping you can have. I don’t see how there would be room inside a fork upper/lower because you need room for the fork to compress into itself.
I did see this photo of Commencal testing something on the lower. Not sure if it’s Tmd or vorsprungs secus.
Yeah, I thought about that, but you could conceivably fit one inside a 40mm stanchion, which means you could also be crazy and have one mounted to the bottom of the fork lower and have your stanchion compress around it as your fork bottoms out. Kinda wild, but there's room to do it. You wouldn't want to lose that precious real estate on a spring side, but you could do that on the damper side and run a shorter damper. In fact, if you were in a hurry, you could even borrow and mininimally adapt a damper out of a 190mm Zeb or 180mm Fox 38 and run it on top of the internal TMD. Remember the extended stanchion Greg or someone was running, that had an extra 10-15mm of gold Kashima stanchion threaded onto the top of one of the fork legs? That could also help buy you extra real estate for an internal TMD and a damper in your fork leg.
It would be waaaaaay easier to just zip tie it to the fork lowers though! Maybe that's what we see in the Commencal/Muc-Off image you linked above.
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…
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have everything smash as you get deep in the travel?
Air side I couldn’t see it working because then your neg/pos air chamber ratio is mixed up.
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have...
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have everything smash as you get deep in the travel?
Air side I couldn’t see it working because then your neg/pos air chamber ratio is mixed up.
Could a small tmd replace the area where the volume reducers sit in the positive air chamber? I think a 200mm Fox 40 can handle up to 5, so theoretically it could fit and maybe clip onto the air cap in the same way.
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have...
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have everything smash as you get deep in the travel?
Air side I couldn’t see it working because then your neg/pos air chamber ratio is mixed up.
It would be hard to handle rebound at the bottom of the damper with a TMD in the way.
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have...
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have everything smash as you get deep in the travel?
Air side I couldn’t see it working because then your neg/pos air chamber ratio is mixed up.
Could a small tmd replace the area where the volume reducers sit in the positive air chamber? I think a 200mm Fox 40 can handle up...
Could a small tmd replace the area where the volume reducers sit in the positive air chamber? I think a 200mm Fox 40 can handle up to 5, so theoretically it could fit and maybe clip onto the air cap in the same way.
100% agree it could fit there. But then you are stuck with a progressive air spring. So it would be a trade off if you want to dampen frequency or have volume spacers. Also it was mounted to the “crown of the fork” where the volume spacers sit, it would be unsprung, so you might as well mount on the outside of fork like Trek is doing.
You’d need to mount on or inside the fork lower to have it work like the Mondraker rear axle TMD
100% agree it could fit there. But then you are stuck with a progressive air spring. So it would be a trade off if you want...
100% agree it could fit there. But then you are stuck with a progressive air spring. So it would be a trade off if you want to dampen frequency or have volume spacers. Also it was mounted to the “crown of the fork” where the volume spacers sit, it would be unsprung, so you might as well mount on the outside of fork like Trek is doing.
You’d need to mount on or inside the fork lower to have it work like the Mondraker rear axle TMD
If you’re TMD is sprung with coils, you could leave it open via a hole in the side somewhere and then the volume difference would be only the volume of the solids.
100% agree it could fit there. But then you are stuck with a progressive air spring. So it would be a trade off if you want...
100% agree it could fit there. But then you are stuck with a progressive air spring. So it would be a trade off if you want to dampen frequency or have volume spacers. Also it was mounted to the “crown of the fork” where the volume spacers sit, it would be unsprung, so you might as well mount on the outside of fork like Trek is doing.
You’d need to mount on or inside the fork lower to have it work like the Mondraker rear axle TMD
If you’re TMD is sprung with coils, you could leave it open via a hole in the side somewhere and then the volume difference would be...
If you’re TMD is sprung with coils, you could leave it open via a hole in the side somewhere and then the volume difference would be only the volume of the solids.
I mean, it’s 100% inside of the forks at this point. Sprung, unsprung, spring side, damper side. There are different solutions and different applications and different benefits/compromises but regardless of the debate, they’re in there.
Question: will they ever feature on a consumer fork? Is this going to be a vorsprung-level aftermarket bit? Or a ultimate-level “buttercup” type bit?
I still haven’t even hit 40lbs on my alloy enduro bike so I would def drop one of these in the zeb if it was possible, but maybe the size means it’s a 200mm only application? (Unless it’s a strap-on)
It depends on what vibrations you're trying to damp. If you're trying to damp the natural frequency of braking bumps, then I think mounting to the...
It depends on what vibrations you're trying to damp. If you're trying to damp the natural frequency of braking bumps, then I think mounting to the sprung mass is the clear pick. If you're trying to damp the natural frequency of the tires (tires are a largely undamped air spring), then mounting to the unsprung rear triangle would make sense. The seat tube is about 450 cm away from the rear axle, whereas the fork-mounted TMD is sitting almost directly inline with the front axle, so the front mount is in a much better position to damp suspension movement than a rear mount on the seat tube.
If you wanted to use a rear TMD to damp rear suspension movement and sprung mass, you'd almost want to construct an ugly triangular wheelie bar off the back of the bike to mount the TMD to, bolted onto the sprung mass of the main triangle. Obviously that's ugly as hell and no one's ever going to do it, so the Mondraker approach is an interesting alternative. Seems like Mondraker is damping front sprung mass and rear unsprung mass.
one thought - perhaps they're placing it near the BB / cranks as that is near a primary contact point with the rider (feet/pedals)?
I didn’t notice any difference in traction to my feet using flat pedals. But notice more planted feel of the bike in general.
I didn’t notice any difference in traction to my feet using flat pedals. But notice more planted feel of the bike in general.
Would/could a rider on flats be looking for more stable and planted a bottom bracket than a clipless rider?
I've only experienced flats because my brains are dumb, I have a long time riding flats in a past life as a street bmx rider, and I'm still pushing too hard and making dumb mistakes that would be worsened by being clipped in. So I don't really know shit in this department (or many others!).
Is the experience on a DH bike with flats much different than with clipless? I would imagine that a calmer bottom bracket would translate to being easier to stay planted on flat pedals. Some of my riding is poppy and jumpy and wiggly; I can see positives and negatives (only a couple, really) to being more stuck more to the pedals. Is there any time a clipless rider would want a bike to be less planted and more maneuverable/manipulatable via foot movement?
Would/could a rider on flats be looking for more stable and planted a bottom bracket than a clipless rider?I've only experienced flats because my brains are...
Would/could a rider on flats be looking for more stable and planted a bottom bracket than a clipless rider?
I've only experienced flats because my brains are dumb, I have a long time riding flats in a past life as a street bmx rider, and I'm still pushing too hard and making dumb mistakes that would be worsened by being clipped in. So I don't really know shit in this department (or many others!).
Is the experience on a DH bike with flats much different than with clipless? I would imagine that a calmer bottom bracket would translate to being easier to stay planted on flat pedals. Some of my riding is poppy and jumpy and wiggly; I can see positives and negatives (only a couple, really) to being more stuck more to the pedals. Is there any time a clipless rider would want a bike to be less planted and more maneuverable/manipulatable via foot movement?
I've ridden both but predominantly use clips for mountain biking, and used to find if I switched back to flats on the DH bike they could get bounced a little bit on certain bumpy sections, so I imagine it could help with those situations. Its probably exaggerated by being used to clips - if I was riding flats full time it might not be an issue
It took reading four pages of mountain bike discussion, but I just remembered they have giant TMDs inside of skyscrapers to resist wind and earthquakes.
Edit: somehow can‘t upload a photo but it‘s the counterscycle product that‘s seen on Loris (and others) bikes that‘s available to purchase
After all the hype and talk I couldn‘t ressist…
From shaking it in my hand I can feel there‘s a weight in there moving up and down. Without riding the bike I can‘t tell if there‘s anything going on. Looking to take it out to a trail the next weekend. I‘m still thinking about the placement on the fork/steerer area.
Is there a reason to put it right or left? And how much up or down on the fork?
Edit: somehow can‘t upload a photo but it‘s the counterscycle product that‘s seen on Loris (and others) bikes that‘s available to purchaseAfter all the hype and...
Edit: somehow can‘t upload a photo but it‘s the counterscycle product that‘s seen on Loris (and others) bikes that‘s available to purchase
After all the hype and talk I couldn‘t ressist…
From shaking it in my hand I can feel there‘s a weight in there moving up and down. Without riding the bike I can‘t tell if there‘s anything going on. Looking to take it out to a trail the next weekend. I‘m still thinking about the placement on the fork/steerer area.
Is there a reason to put it right or left? And how much up or down on the fork?
Doesn't matter where you place it as long as it doesn't hit anything at full travel. Looks wise I like the front placement as on loris bike but you most likely bought one that mounts on the stanchion so that is out of question now.
Doesn't matter where you place it as long as it doesn't hit anything at full travel. Looks wise I like the front placement as on loris...
Doesn't matter where you place it as long as it doesn't hit anything at full travel. Looks wise I like the front placement as on loris bike but you most likely bought one that mounts on the stanchion so that is out of question now.
Maybe I can put some spacers together to also mount it on the steerer tube to be also able to use it on different bikes
TMD in helmets or on a belt around the waist? A lot of crazy stuff happens when people and bodies get bounced around. What if we calmed the body and let the bike get a little crazy? Or maybe on the fork and waist?
A calm body with shoulders and hips pointed in the right direction certainly does a lot to help riders stay stable. I wonder if calming the front of the bike and calming the rider's center of gravity would absolve some sins committed by the rear triangle? Would there be any benefit to TMD just above the ankles? You'd probably have to be clipped in for that but that might mean the rider can have the most influential calming input on a bike from the most solid contact point.
Also, I don't know anything. I have SOME THOUGHTS, but I'm not able to brains-work the physics of it all right now. And even if I stumbled on a perfect idea I don't know if I'd know enough to know I did. These might all be really dumb ideas but the thoughts of how to use TMDs on-bike or on-rider definitely makes me curious.
Edit: somehow can‘t upload a photo but it‘s the counterscycle product that‘s seen on Loris (and others) bikes that‘s available to purchaseAfter all the hype and...
Edit: somehow can‘t upload a photo but it‘s the counterscycle product that‘s seen on Loris (and others) bikes that‘s available to purchase
After all the hype and talk I couldn‘t ressist…
From shaking it in my hand I can feel there‘s a weight in there moving up and down. Without riding the bike I can‘t tell if there‘s anything going on. Looking to take it out to a trail the next weekend. I‘m still thinking about the placement on the fork/steerer area.
Is there a reason to put it right or left? And how much up or down on the fork?
Doesn’t matter which side or center. The lower you can get it, the less “top” heavy your bike will feel when laying it over from side to side.
I did a test this weekend with and without countershox on the bike. Nothing else was changed besides one on the fork and one on the seattube. The feeling in my hands was night and day more comfortable with Countershox.
I was running data sensors on the bike for suspension, axles, bb and headtube of frame.
This graph is a snippet showing the front axle movement compared to handlebar movement in vertical direction. Red is bars and Yellow is axle.
You can see the bottom graph between big hits the bars are moving vertically much less. The peaks of the bar movement was also decreased.
It’s subtle on graph, but feeling to me was much greater of a change. I also notice more grip and confidence while using the countershox.
When the mass slides one direction, the spring backing it in the direction it slides sees increase in force while the spring on the other side sees a decrease. If the spring rates are the same, the one spring force increases the same amount that the other spring force decreases. As a result, the net force is double what it would be with that displacement and a single spring.
A numeric example with easy numbers would be two springs with a 50 lb/in rate preloaded to 100 lbs each. When the mass is translated 1” to one side, one spring is now applying 150 lbs to the mass and the other is applying 50 lbs for a net force of 100 lbs. So in that 1” displacement the net force changes by 100 lbs which is a 100 lb/in effective spring rate.
Yeah I think you are right - I realised I hadn't thought that through enough and once I sat down to work through the numbers that seems to check out. I'll try work out some more precise numbers and repeat the test, hopefully find a TMD arrangement where the frequency is too high to work properly as well as too low. Maybe some potentiometers on the tyre & mass to see how much displacement each is going through as well....
Saw this in PitBits. Looks like the TMD have made it to Enduro racing.
Some dumb questions now that I'm catching up on this thread:
1. If the swingarm mounted TMD and the frame mounted TMD damp different frequencies (big impacts vs. tire bounce), would there be a benefit in running both simultaneously? Or would the two TMD's fight each other and you have a three-body problem?
2. Dak said there's hidden tech, and they're mounting their rear TMD to the rear axle. What if the hidden component is inside the fork, but mounted to the unsprung mass? It could be inside the fork lowers mounted at the bottom, as opposed to the sprung mass dampers we've seen from Countershox and Rimpact that are mounted to the top of the fork or in the steerer tube?
3. How long until someone in this thread buys a shakeweight and bolts it to their bike? Just a matter of time.
I don’t see a reason why you couldn't mount to frame and axle besides asking yourself how much do you want your bike to weigh?
I had a Commencal V5 that was 43lb, session was 41lb with the same parts. I can’t really imagine adding more than 1-2lb to that.
I feel like Mondraker might be using one in steerer tube. But that limits the mount of weight and damping you can have. I don’t see how there would be room inside a fork upper/lower because you need room for the fork to compress into itself.
I did see this photo of Commencal testing something on the lower. Not sure if it’s Tmd or vorsprungs secus.
Yeah, I thought about that, but you could conceivably fit one inside a 40mm stanchion, which means you could also be crazy and have one mounted to the bottom of the fork lower and have your stanchion compress around it as your fork bottoms out. Kinda wild, but there's room to do it. You wouldn't want to lose that precious real estate on a spring side, but you could do that on the damper side and run a shorter damper. In fact, if you were in a hurry, you could even borrow and mininimally adapt a damper out of a 190mm Zeb or 180mm Fox 38 and run it on top of the internal TMD. Remember the extended stanchion Greg or someone was running, that had an extra 10-15mm of gold Kashima stanchion threaded onto the top of one of the fork legs? That could also help buy you extra real estate for an internal TMD and a damper in your fork leg.
It would be waaaaaay easier to just zip tie it to the fork lowers though! Maybe that's what we see in the Commencal/Muc-Off image you linked above.
<3
I just don’t see how you can put it in a fork on the damper side and still have comp and rebound control or not have everything smash as you get deep in the travel?
Air side I couldn’t see it working because then your neg/pos air chamber ratio is mixed up.
Could a small tmd replace the area where the volume reducers sit in the positive air chamber? I think a 200mm Fox 40 can handle up to 5, so theoretically it could fit and maybe clip onto the air cap in the same way.
It would be hard to handle rebound at the bottom of the damper with a TMD in the way.
100% agree it could fit there. But then you are stuck with a progressive air spring. So it would be a trade off if you want to dampen frequency or have volume spacers. Also it was mounted to the “crown of the fork” where the volume spacers sit, it would be unsprung, so you might as well mount on the outside of fork like Trek is doing.
You’d need to mount on or inside the fork lower to have it work like the Mondraker rear axle TMD
If you’re TMD is sprung with coils, you could leave it open via a hole in the side somewhere and then the volume difference would be only the volume of the solids.
I mean, it’s 100% inside of the forks at this point. Sprung, unsprung, spring side, damper side. There are different solutions and different applications and different benefits/compromises but regardless of the debate, they’re in there.
Question: will they ever feature on a consumer fork? Is this going to be a vorsprung-level aftermarket bit? Or a ultimate-level “buttercup” type bit?
I still haven’t even hit 40lbs on my alloy enduro bike so I would def drop one of these in the zeb if it was possible, but maybe the size means it’s a 200mm only application? (Unless it’s a strap-on)
one thought - perhaps they're placing it near the BB / cranks as that is near a primary contact point with the rider (feet/pedals)?
That's an interesting thought.
Does that TMD placement effect someone riding flats differently than someone riding clipless? Are their any patterns to observe currently?
I didn’t notice any difference in traction to my feet using flat pedals. But notice more planted feel of the bike in general.
Would/could a rider on flats be looking for more stable and planted a bottom bracket than a clipless rider?
I've only experienced flats because my brains are dumb, I have a long time riding flats in a past life as a street bmx rider, and I'm still pushing too hard and making dumb mistakes that would be worsened by being clipped in. So I don't really know shit in this department (or many others!).
Is the experience on a DH bike with flats much different than with clipless? I would imagine that a calmer bottom bracket would translate to being easier to stay planted on flat pedals. Some of my riding is poppy and jumpy and wiggly; I can see positives and negatives (only a couple, really) to being more stuck more to the pedals. Is there any time a clipless rider would want a bike to be less planted and more maneuverable/manipulatable via foot movement?
I've ridden both but predominantly use clips for mountain biking, and used to find if I switched back to flats on the DH bike they could get bounced a little bit on certain bumpy sections, so I imagine it could help with those situations. Its probably exaggerated by being used to clips - if I was riding flats full time it might not be an issue
It turns out Fanatik is already way ahead of the curve for all your shake weight tuning....
https://www.youtube.com/watch?v=sesdLpRneHs
I think it will need a stiffer spring for bolting to your bike though!
It took reading four pages of mountain bike discussion, but I just remembered they have giant TMDs inside of skyscrapers to resist wind and earthquakes.
Edit: somehow can‘t upload a photo but it‘s the counterscycle product that‘s seen on Loris (and others) bikes that‘s available to purchase
From shaking it in my hand I can feel there‘s a weight in there moving up and down. Without riding the bike I can‘t tell if there‘s anything going on. Looking to take it out to a trail the next weekend.
I‘m still thinking about the placement on the fork/steerer area.
Is there a reason to put it right or left? And how much up or down on the fork?
Doesn't matter where you place it as long as it doesn't hit anything at full travel. Looks wise I like the front placement as on loris bike but you most likely bought one that mounts on the stanchion so that is out of question now.
Maybe I can put some spacers together to also mount it on the steerer tube to be also able to use it on different bikes
Dumb ideas:
TMD in helmets or on a belt around the waist? A lot of crazy stuff happens when people and bodies get bounced around. What if we calmed the body and let the bike get a little crazy? Or maybe on the fork and waist?
A calm body with shoulders and hips pointed in the right direction certainly does a lot to help riders stay stable. I wonder if calming the front of the bike and calming the rider's center of gravity would absolve some sins committed by the rear triangle? Would there be any benefit to TMD just above the ankles? You'd probably have to be clipped in for that but that might mean the rider can have the most influential calming input on a bike from the most solid contact point.
Also, I don't know anything. I have SOME THOUGHTS, but I'm not able to brains-work the physics of it all right now. And even if I stumbled on a perfect idea I don't know if I'd know enough to know I did. These might all be really dumb ideas but the thoughts of how to use TMDs on-bike or on-rider definitely makes me curious.
Doesn’t matter which side or center. The lower you can get it, the less “top” heavy your bike will feel when laying it over from side to side.
I did a test this weekend with and without countershox on the bike. Nothing else was changed besides one on the fork and one on the seattube. The feeling in my hands was night and day more comfortable with Countershox.
I was running data sensors on the bike for suspension, axles, bb and headtube of frame.
This graph is a snippet showing the front axle movement compared to handlebar movement in vertical direction. Red is bars and Yellow is axle.
You can see the bottom graph between big hits the bars are moving vertically much less. The peaks of the bar movement was also decreased.
It’s subtle on graph, but feeling to me was much greater of a change. I also notice more grip and confidence while using the countershox.
Post a reply to: Tuned Mass Dampers and Mountain Bikes