RideMonkey How To Series: Throwing a Tantrum in Public
Some do. but we don't play there. We have a choice. Not everybody is a crook
The interesting thing about this is, it depends entirely on how many people enter. Right? If there are 5 quality entries, they all get something, and probably more biz afterward. Sure, there will be some shit entries. I don't feel bad about those people working for free. They probably need the practice.
But I will feel bad that I don't have more bikes to use more different graphics. Who knows, I might amend the agreement to allow a different design on a future model. Or at least put that in the agreement that if I DO use it in the future, they retroactively win. hmmmm
Why is that aggressive?? I'm fine with not everyone loving me, especially on the web. And trying to shoot an idea down. that's what forums are for. I didn't event that people are resistant to change, did I? Were you around when suspension first came out? Good thing the internet wasn't around then. You'd've thought we were raising satan.
And then , disc brakes, what a bunch of BS and snake oil. You can see this same kind of discussion happening on that 15-18 years ago. Some of them with me involved.
It doesn't surprise me that Hugh's bike is easier to understand. It IS easier to understand. And measure in conventional terms. Ground breaking enough? Not really. People have been playing with high pivots with chain torque modification for decades. I had a high derailleur with a jockey wheel so I could shift it in the 90's. So, he has his own take on it based on what he wants as a rider.
The Missing Link is different. Nobody has attempted or achieved this before. It is difficult to understand. I have to reiterate aspects to myself to keep it all in my head. It's not a trivial problem to analyze or design. So, if you (or an engineer) doesn't understand it, or is making an error in analysis, I will correct that. Aggressive?? ok.
As for input from other engineers, it's kinda hard to tell who is who, but I don't think too many engineers have delved in too deeply here, just based on the comments.
An engineering discussion is open minded. It is necessary to remove as many pre-conceived notions as you can. In the end, whenever anyone has tried to bring up an engineering point, I will answer in the best way I can, with an engineering answer. And sorry, AS and LR are such a tiny part of it. They're like catch phrases everyone likes to sling around.
But mostly, i get things lik,e "that can't happen" " you're a liar" " new psuedo physics". Whatever, those aren't really engineering discussions. It reminds of a patent examiner that told me one of my damper patents was not physically possible. I mentioned that I had a working model and volunteered to fly to DC and demonstrate it. They granted the patent.
I've asked guys to publish their analysis. This includes the starting inputs. Nothing. One guy posted really really bad LR and AS curve that I've discussed at length. About 40% of his graph was off the charts. When I mention things like rising rate springs taking over for an initially falling and then linear LR, nobody makes a comment. When I talk about forces on the Missing Link and how they are input into the suspension and actually show that in my video, nobody offers up a calculation to dispute it, they just say I made that up, and my video is bogus because I pulled a bolt out to show forces independently. Like I was trying to deceive people into thinking the links moved independently.
I'm sure plenty of engineers hate me. have you met us?? (engineers). I have no problem with that. But there are a high number of professional engineers that have looked at the design and get it. Period. If you want to get, you will. If you don't, you won't. Is that an insult?? No. It's just true. I can post all the numbers you want, but if you can't believe it could be possible, it won't matter, right?
This one is easy to answer. I just cut and pasted my response to westy a few pages back:
In the video, at the bottom of the climb is a pretty good g-out. You come blasting down a hill, across a bridge and try to hit the bottom with all the speed you can, while simultaneously grabbing a handful of gears for the effort at the top. You have to hit it fast or you won't make the climb (at least I won't).
Also, the bike doesn't use as much travel as it appears. It's a little deceiving to look at, as the last 15 mm of shaft or so are not visible due to the shock being sunk into the frame. The amount of travel the Tantrum uses there is about the same as every other bike I've ridden there for the past 15 years.
When you hit shit fast going DH? Smooth, plush, bottomless. Fun. I recently did some shuttle runs at Big Bear with a 260 lb former DH pro. Put 220 psi in and sent him. Super plush, bottomless with good reserve.
because they are shit, and you really shouldn't be designing an entire bike to work in mediocre fashion in concert with a specific spring. We would tell you that, but you'd post another overly defensive diatribe on how right you are and how wrong virtually everybody else designing and riding bikes is wrong.
You should design it to work well, in spite of any shock that may be attached. Air shock are constantly being refined to mimic coil springs. Are you setting your enduro bike up to be run with a decade old small canister air shock? Besides all that, why the hell would you want a falling rate in the first third of travel? That's simply bad design.
Wait, norbar, are you reading this engineering discussion?? "because they are shit". Let's see, if we calculate it out.....because they are shit, and you really shouldn't be designing an entire bike to work in mediocre fashion in concert with a specific spring. We would tell you that, but you'd post another overly defensive diatribe on how right you are and how wrong virtually everybody else designing and riding bikes is wrong.
You should design it to work well, in spite of any shock that may be attached. Air shock are constantly being refined to mimic coil springs. Are you setting your enduro bike up to be run with a decade old small canister air shock? Besides all that, why the hell would you want a falling rate in the first third of travel? That's simply bad design.
You are correct, you shouldn't be designing a bike to work in mediocre fashion in concert with a specific spring. Of course not. So I didn't. One specific spring? You do realize it's an air shock with a pretty wide range of spring rates, right? And how, exactly, is that different than every other bike? Every suspension designer out there makes some effort to match their design with the shock. Many fail, which is why you see plenty of reviews adding or subtracting volume spacers, etc.
BTW, I NEVER said other bikes, suspension, etc, is wrong. On the contrary, it's hard to find a bad bike these days. We've reached a kind of plateau of development. Most brands are pretty settled on their platform and content to do minor tweaks. There are exceptions, but this is moslly true. Is my design RIGHT? depends on if you value increased pedaling performance, climbing geometry, bump absorption and descending geometry in exchange for a few extra bearings and a unique appearance. Many won't. They like a simple single pivot bike. It's not wrong, I like them too.
When I am telling people they are wrong is when the present data that they purport to be an accurate analysis. I tell them it is wrong, because it is.
No suspension will work optimally well with random shock changes. Some shocks aren't that good!! but why do I need to design my suspension to work with shocks designed for other suspensions. That doesn't make any sense. I've been designing shocks for 30 years, I do believe I can spec a valving and rate that is optimal for my design. And do without such nonsense as "pedaling platforms" and other "developments" that just make shocks worse over bumps.
You say "why the hell would you want a falling rate in the first third of travel? That's simply bad design." How do you not that without combining all of the effects from all the forces?? You can't say, because I've ridden bikes with falling rates like that. For one, there is a MEGAHUGE range of what a falling rate even means. Secondly, those bikes you may hav ridden did not have the same force management capability as the Missing Link. They cannot possible act the same, even if their falling rates were identical. So you can't possibly know that "that's simply bad design".
I chose a falling rate for that part of the travel because that is the area of travel that I want the wheel to move as fast as possible when it hits the bump. On a conventional suspension, you cannot get away with this. For all of the reasons you are thinking of. On this design, I can, due to the force management thru the Missing Link. It let's the wheel respond quickly. The falling rate on compression also translates to a rising rate in the rebound direction. This gives the wheel quicker rebound response in mid travel to keep it from wallowing, with a slower rebound as it approaches topout. This helps avoid any kind of pitching forward, for example on a jump.
And what, exactly is wrong with a nice smooth progressive rising rate air spring? Well, when paired with the typical rising rate LR, there's too much rise. That's why the availability of large cans.Funny thing is, they spec these large cans and fill them up with volume spacers. Why? because large can is IN.
Those graphics were based on the "scare the air" theory of aerodynamics. I pioneered that during my time in car racing
Ok here's the thing you just don't get.
On this forum (and others), not only are there actual mechanical engineers, but there are bike company owners and designers who post here. None of them attack or relentlessly defend their products with long winded, condescending diatribes. If you are really trying to grow a business, the last thing you want to do is insult and alienate your potential customer base.
People on the internet are going to make ridiculous comments no matter what is being discussed. When you start replying to all of them you just make yourself look like an insecure ass with way too much time on your hands. Try spending more energy growing your company, than arguing with strangers online.
On another forum, the company designer of the bike I ride, posts regularly and is not only gracious, but supportive and professional. This is one of the reasons said company has a cult like following of hardcore riders. Customer service is everything to maintaining a solid reputation and to continue to grow.
All you have done is tell people they're stupid and can't possibly understand what your brilliant mind has conceived. The way you conduct yourself on a forum is a pretty good indicator of what your customer service will be like. And quite frankly, I and probably a lot of others on here, would never buy a bike from you solely because of that.
Let that sink in for a minute before you rattle off a 400 word retort.
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I don't understand why you're even building frames.
Why not just license it to brands who have fanboi's that buy whatever they schlep?
Of course, that requires interest from The Industry. (capitalized for DW dramatic effect)
In this competitive market full of licensed designs, groundbreaking technology would be adopted immediately.
If it's worth a damn, that is.
Why not just license it to brands who have fanboi's that buy whatever they schlep?
Of course, that requires interest from The Industry. (capitalized for DW dramatic effect)
In this competitive market full of licensed designs, groundbreaking technology would be adopted immediately.
If it's worth a damn, that is.
i've designed and gotten houses thru building and safety for items plenty of times, bikes included...
nobody is taking advantage of anyone. if you don't think it's worth your time, don't do shit then...
nobody is taking advantage of anyone. if you don't think it's worth your time, don't do shit then...
Hi dan-o. Why am I building frames? To increase the value of the IP. I have been and will continue to talk to various brands. But, they are all on a minimum 2 year product development cycle. Most are stuck into carbon mold costs for 3 years to amortize the costs. There is a strong likelihood that you will see at least one, maybe more brands licensing for 2018. Those are ones NOT locked in to a current design. i had one company wanting it so bad they were drooling. Then they did the math of redoing all 9 of their carbon bikes. The PM called me almost crying. They didn't have the money. This particular company sells a nice range of horst link bikes, old hat. But, they're nice, and dialed and they're selling,
There are a few guys waiting to see what happens. For example, when the PB review hit, the phone rang from a couple PM's that day. Then it's not just me saying it works great. It's known and trusted sources that most of these guys have known for a long time. As the bikes filter into the hands of customers, the word will spread. This will make other brands hungry for it. I will also have demo rides at Eurobike and Interbike, so PM's can get a back to back picture. As I've said here many times, no proof like the riding, until then, it's just talk.
When I did the Magic Link Bike, I sold them the idea and gave them an exclusive. It worked pretty well, but I wanted to try something different this time. This thing works. So, I am kinda calling this the horst leitner plan. Start a little bike company. License it to everyone. Or, sell my bikes and have fun. I don't need to get rich. I just want people to get to ride my bike and enjoy my work. AND racing my own brand at the Sea Otter Enduro was just plain cool.
Call it a reallly cool, fun thing that I'm lucky I get to do.
Unless it's someone that I know, I don't pay attention to any magazine reviews, they usually tend to say everything is great, when sometimes it's 180 degrees in the opposite direction. Things like bump absorption, pedaling, chassis stability, user-serviceability, and so on. They are way too afraid to point out the actual differences between bikes and try to rate them on a semi-objective scale. F-them.
One of my primary goals with i-track has been to provide a factual resource about suspension theory and design, to try and counteract the sea of false claims and misinformation that exists elsewhere on the topic.
Suspension theory isn't for everyone; the majority of riders aren't that interested in it, let alone understand it.
People buy bikes for any number of reasons: colour, style, weight, status, suspension performance. Each to their own.
What bothers me, is when someone hands over some hard-earned $$ to buy a bike because they have been led to believe that the suspension will perform better than others, when it won't.
Since you're not selling bikes yet, you haven't crossed this line. But I urge you to re-consider some of what you think you know, so you can provide some more truthful information to your potential customers.
As for an engineering discussion, here are some well-established facts, and subsequent conclusions based on those facts.
Anti-Squat:
Fact 1. On your bike, the axle path is determined by a 6-bar linkage. All links and pivots are required in this system to constrain the axle path to 1dof.
Fact 2. For this arrangement, like the majority of other bike suspension designs (BB on front triangle, with conventional drivetrain) the axle path determines whether the suspension will exhibit an extension or compression (or zero) force when pedalling.
If the axle path is perfectly perpendicular to the propulsion force at the axle, then there is zero extension or compression force exhibited in the suspension when pedalling.
If the axle path is slightly rearward of perpendicular, then there will be an extension force in the suspension when pedalling, therefore positive AS value. (more rearward = more AS).
If the axle path is slightly forward of perpendicular, then there will be a compression force in the suspension when pedalling, therefore negative AS value. (more forward = less AS).
Fact 3. In a 1dof planar linkage, there is an Instant Centre (IC) between any two links. For bike suspension analysis, we are interested in the IC of the 'wheel link' relative to the 'front triangle' link. This IC defines the axle path. Once this IC is located, there is no need to consider the free-body forces on individual links (unless you're doing a structural analysis on a particular link). That is why engineers always go on about Instant Centres. Because they tell us exactly what the linkage is doing, without having to perform a time-consuming free-body analysis.
Fact 4. There is a graphical method for determining the ICs of any planar linkage, and it produces the same result as a free-body analysis, with much less work. It's amazing how a graphical method can perform calculations without having to actually calculate anything. This is not new technology, it's been around for a while. Try googling Kennedy's theorem.
Most people around here know how to locate the IC for a 4-bar linkage (by intersecting the lines through the two intermediate links).
Few people know how to locate the IC for a 6-bar linkage. Two seconds of googling yields a PDF of how real engineers locate the IC of a 6-bar linkage using Kennedy's theorem. Click this link:
Note, the small circle diagram is used to determine the algorithm required to locate the unknown ICs using the graphical method. On this circle diagram, the numbers around the outside represent the links, and the lines between the numbers represent ICs between that pair of links.
This circle diagram can be used to develop the appropriate graphical method algorithm for ANY 1dof planar linkage.
This is really really really powerful stuff, and I suggest that you take some time understanding how it works. Start with a 4-bar.
Linkage software uses this exact process to develop the appropriate algorithm for determining ICs for 4-bar, 6-bar and more complex linkages. I'm confident it is applied correctly in the software.
Fact 5: In terms of pedalling performance, there is absolutely nothing going on in your suspension that isn't described by the IC path.
Given that up until two weeks ago, you were adamant that your system was a 5-bar linkage, and that you also mentioned somewhere that you hadn't used Linkage software, I wonder how you think you have located the IC for your suspension system? Did you try and use the 4-bar graphical method, if so, it won't give you the correct answer. Did you use the appropriate method based on Kennedy's theorem? I doubt it.
I suspect that you haven't actually located the IC, and therefore can't have properly quantified the anti-squat characteristics. Yet you have voracity to tell @Vrock that "He's wrong" and uses "poor analysis".
The only thing 'wrong' about @Vrock 's analysis would come from inaccuracies due to modelling off a photograph, which he has do because you are not prepared to provide some simple pivot locations that anyone with half a brain could measure off one of your bikes once they are available.
Until you provide more accurate info, @Vrock's analysis is the most accurate assessment available. Why? Because it's based on these facts above.
Leverage Ratio:
Fact 6. Leverage Ratio (LR) is defined as the ratio of Vertical Wheel Travel (VWT) to Shock Compression, at a given point in travel. This ratio generally varies throughout suspension travel.
Fact 7. LR wholly describes the relationship between wheel travel and shock travel (and therefore wheel force and shock force). This is the only function by which the wheel movement 'communicates' to the shock. Just because the shock eye happens to be at the same location as the pivot between two links, does not make this suspension any different.
In one of your videos, you disconnect the linkage and demonstrate how a bit of chain tension pulls the chainstay forward, which rotates the 'missing link' and applies extension force to the shock. The implication being that this is what happens when riding.
What you are ignoring, is that when the rest of the linkage is connected, it opposes that extension force on the shock. E.g. forward force on the axle puts the seat stay link in compression, rotating the upper rocker link forwards, pushing down on the link that connects the rocker to the shock, therefore applying a compressive force to the shock (almost completely counteracting the extension force on the shock by the 'missing link').
If you apply a force at the axle that is perpendicular to the axle path, then there is no resultant force on the shock.
With your system, because of the axle path, there is a slight overall extension force on the shock due to pedalling, especially near top out. The magnitude of this force is dependent on the axle path, which is reflected in Anti-Squat calculations already discussed above.
Please don't simply respond by saying "you don't understand" or "but this suspension is different". I happen to have a pretty good grasp on this topic, and I can assure you there is absolutely nothing going on in your suspension kinematics that is beyond the AS and LR facts listed above. The laws of physics still apply.
I hope you take the time to read and understand the theory behind planar linkages. As you say, it's not simple. But it really does make a lot of sense when you fully understand it.
Furthermore once you start coming round (hopefully) to understanding the theory a bit better, you will recognise that our obsession with AS and LR (and AR) is justified, as these parameters fully describe the kinematics of a suspension system.
If you're not prepared to open your mind to the many well-informed people trying to explain it to you, then I give up. It's clear that you're set in your ways and not prepared to learn something new. Hopefully that's not true.
Regards,
Hugh McLeay
Suspension theory isn't for everyone; the majority of riders aren't that interested in it, let alone understand it.
People buy bikes for any number of reasons: colour, style, weight, status, suspension performance. Each to their own.
What bothers me, is when someone hands over some hard-earned $$ to buy a bike because they have been led to believe that the suspension will perform better than others, when it won't.
Since you're not selling bikes yet, you haven't crossed this line. But I urge you to re-consider some of what you think you know, so you can provide some more truthful information to your potential customers.
As for an engineering discussion, here are some well-established facts, and subsequent conclusions based on those facts.
Anti-Squat:
Fact 1. On your bike, the axle path is determined by a 6-bar linkage. All links and pivots are required in this system to constrain the axle path to 1dof.
Fact 2. For this arrangement, like the majority of other bike suspension designs (BB on front triangle, with conventional drivetrain) the axle path determines whether the suspension will exhibit an extension or compression (or zero) force when pedalling.
If the axle path is perfectly perpendicular to the propulsion force at the axle, then there is zero extension or compression force exhibited in the suspension when pedalling.
If the axle path is slightly rearward of perpendicular, then there will be an extension force in the suspension when pedalling, therefore positive AS value. (more rearward = more AS).
If the axle path is slightly forward of perpendicular, then there will be a compression force in the suspension when pedalling, therefore negative AS value. (more forward = less AS).
Fact 3. In a 1dof planar linkage, there is an Instant Centre (IC) between any two links. For bike suspension analysis, we are interested in the IC of the 'wheel link' relative to the 'front triangle' link. This IC defines the axle path. Once this IC is located, there is no need to consider the free-body forces on individual links (unless you're doing a structural analysis on a particular link). That is why engineers always go on about Instant Centres. Because they tell us exactly what the linkage is doing, without having to perform a time-consuming free-body analysis.
Fact 4. There is a graphical method for determining the ICs of any planar linkage, and it produces the same result as a free-body analysis, with much less work. It's amazing how a graphical method can perform calculations without having to actually calculate anything. This is not new technology, it's been around for a while. Try googling Kennedy's theorem.
Most people around here know how to locate the IC for a 4-bar linkage (by intersecting the lines through the two intermediate links).
Few people know how to locate the IC for a 6-bar linkage. Two seconds of googling yields a PDF of how real engineers locate the IC of a 6-bar linkage using Kennedy's theorem. Click this link:
Note, the small circle diagram is used to determine the algorithm required to locate the unknown ICs using the graphical method. On this circle diagram, the numbers around the outside represent the links, and the lines between the numbers represent ICs between that pair of links.
This circle diagram can be used to develop the appropriate graphical method algorithm for ANY 1dof planar linkage.
This is really really really powerful stuff, and I suggest that you take some time understanding how it works. Start with a 4-bar.
Linkage software uses this exact process to develop the appropriate algorithm for determining ICs for 4-bar, 6-bar and more complex linkages. I'm confident it is applied correctly in the software.
Fact 5: In terms of pedalling performance, there is absolutely nothing going on in your suspension that isn't described by the IC path.
Given that up until two weeks ago, you were adamant that your system was a 5-bar linkage, and that you also mentioned somewhere that you hadn't used Linkage software, I wonder how you think you have located the IC for your suspension system? Did you try and use the 4-bar graphical method, if so, it won't give you the correct answer. Did you use the appropriate method based on Kennedy's theorem? I doubt it.
I suspect that you haven't actually located the IC, and therefore can't have properly quantified the anti-squat characteristics. Yet you have voracity to tell @Vrock that "He's wrong" and uses "poor analysis".
The only thing 'wrong' about @Vrock 's analysis would come from inaccuracies due to modelling off a photograph, which he has do because you are not prepared to provide some simple pivot locations that anyone with half a brain could measure off one of your bikes once they are available.
Until you provide more accurate info, @Vrock's analysis is the most accurate assessment available. Why? Because it's based on these facts above.
Leverage Ratio:
Fact 6. Leverage Ratio (LR) is defined as the ratio of Vertical Wheel Travel (VWT) to Shock Compression, at a given point in travel. This ratio generally varies throughout suspension travel.
Fact 7. LR wholly describes the relationship between wheel travel and shock travel (and therefore wheel force and shock force). This is the only function by which the wheel movement 'communicates' to the shock. Just because the shock eye happens to be at the same location as the pivot between two links, does not make this suspension any different.
In one of your videos, you disconnect the linkage and demonstrate how a bit of chain tension pulls the chainstay forward, which rotates the 'missing link' and applies extension force to the shock. The implication being that this is what happens when riding.
What you are ignoring, is that when the rest of the linkage is connected, it opposes that extension force on the shock. E.g. forward force on the axle puts the seat stay link in compression, rotating the upper rocker link forwards, pushing down on the link that connects the rocker to the shock, therefore applying a compressive force to the shock (almost completely counteracting the extension force on the shock by the 'missing link').
If you apply a force at the axle that is perpendicular to the axle path, then there is no resultant force on the shock.
With your system, because of the axle path, there is a slight overall extension force on the shock due to pedalling, especially near top out. The magnitude of this force is dependent on the axle path, which is reflected in Anti-Squat calculations already discussed above.
Please don't simply respond by saying "you don't understand" or "but this suspension is different". I happen to have a pretty good grasp on this topic, and I can assure you there is absolutely nothing going on in your suspension kinematics that is beyond the AS and LR facts listed above. The laws of physics still apply.
I hope you take the time to read and understand the theory behind planar linkages. As you say, it's not simple. But it really does make a lot of sense when you fully understand it.
Furthermore once you start coming round (hopefully) to understanding the theory a bit better, you will recognise that our obsession with AS and LR (and AR) is justified, as these parameters fully describe the kinematics of a suspension system.
If you're not prepared to open your mind to the many well-informed people trying to explain it to you, then I give up. It's clear that you're set in your ways and not prepared to learn something new. Hopefully that's not true.
Regards,
Hugh McLeay
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Hi Hugh, Haven't heard from you in a while. I thought we covered this before. My god, son, give it a rest with the condescending. I am a degreed mechanical engineer with 30 plus years of suspension development at the highest possible level of sport. I have some patents. I've raced MX for 15 yrs and DH for 10. Ridden bikes for 50.One of my primary goals with i-track has been to provide a factual resource about suspension theory and design, to try and counteract the sea of false claims and misinformation that exists elsewhere on the topic.
Suspension theory isn't for everyone; the majority of riders aren't that interested in it, let alone understand it.
People buy bikes for any number of reasons: colour, style, weight, status, suspension performance. Each to their own.
What bothers me, is when someone hands over some hard-earned $$ to buy a bike because they have been led to believe that the suspension will perform better than others, when it won't.
Since you're not selling bikes yet, you haven't crossed this line. But I urge you to re-consider some of what you think you know, so you can provide some more truthful information to your potential customers.
As for an engineering discussion, here are some well-established facts, and subsequent conclusions based on those facts.
Anti-Squat:
Fact 1. On your bike, the axle path is determined by a 6-bar linkage. All links and pivots are required in this system to constrain the axle path to 1dof.
Fact 2. For this arrangement, like the majority of other bike suspension designs (BB on front triangle, with conventional drivetrain) the axle path determines whether the suspension will exhibit an extension or compression (or zero) force when pedalling.
If the axle path is perfectly perpendicular to the propulsion force at the axle, then there is zero extension or compression force exhibited in the suspension when pedalling.
If the axle path is slightly rearward of perpendicular, then there will be an extension force in the suspension when pedalling, therefore positive AS value. (more rearward = more AS).
If the axle path is slightly forward of perpendicular, then there will be a compression force in the suspension when pedalling, therefore negative AS value. (more forward = less AS).
Fact 3. In a 1dof planar linkage, there is an Instant Centre (IC) between any two links. For bike suspension analysis, we are interested in the IC of the 'wheel link' relative to the 'front triangle' link. This IC defines the axle path. Once this IC is located, there is no need to consider the free-body forces on individual links (unless you're doing a structural analysis on a particular link). That is why engineers always go on about Instant Centres. Because they tell us exactly what the linkage is doing, without having to perform a time-consuming free-body analysis.
Fact 4. There is a graphical method for determining the ICs of any planar linkage, and it produces the same result as a free-body analysis, with much less work. It's amazing how a graphical method can perform calculations without having to actually calculate anything. This is not new technology, it's been around for a while. Try googling Kennedy's theorem.
Most people around here know how to locate the IC for a 4-bar linkage (by intersecting the lines through the two intermediate links).
Few people know how to locate the IC for a 6-bar linkage. Two seconds of googling yields a PDF of how real engineers locate the IC of a 6-bar linkage using Kennedy's theorem. Click this link:
Note, the small circle diagram is used to determine the algorithm required to locate the unknown ICs using the graphical method. On this circle diagram, the numbers around the outside represent the links, and the lines between the numbers represent ICs between that pair of links.
This circle diagram can be used to develop the appropriate graphical method algorithm for ANY 1dof planar linkage.
This is really really really powerful stuff, and I suggest that you take some time understanding how it works. Start with a 4-bar.
Linkage software uses this exact process to develop the appropriate algorithm for determining ICs for 4-bar, 6-bar and more complex linkages. I'm confident it is applied correctly in the software.
Fact 5: In terms of pedalling performance, there is absolutely nothing going on in your suspension that isn't described by the IC path.
Given that up until two weeks ago, you were adamant that your system was a 5-bar linkage, and that you also mentioned somewhere that you hadn't used Linkage software, I wonder how you think you have located the IC for your suspension system? Did you try and use the 4-bar graphical method, if so, it won't give you the correct answer. Did you use the appropriate method based on Kennedy's theorem? I doubt it.
I suspect that you haven't actually located the IC, and therefore can't have properly quantified the anti-squat characteristics. Yet you have voracity to tell @Vrock that "He's wrong" and uses "poor analysis".
The only thing 'wrong' about @Vrock 's analysis would come from inaccuracies due to modelling off a photograph, which he has do because you are not prepared to provide some simple pivot locations that anyone with half a brain could measure off one of your bikes once they are available.
Until you provide more accurate info, @Vrock's analysis is the most accurate assessment available. Why? Because it's based on these facts above.
Leverage Ratio:
Fact 6. Leverage Ratio (LR) is defined as the ratio of Vertical Wheel Travel (VWT) to Shock Compression, at a given point in travel. This ratio generally varies throughout suspension travel.
Fact 7. LR wholly describes the relationship between wheel travel and shock travel (and therefore wheel force and shock force). This is the only function by which the wheel movement 'communicates' to the shock. Just because the shock eye happens to be at the same location as the pivot between two links, does not make this suspension any different.
In one of your videos, you disconnect the linkage and demonstrate how a bit of chain tension pulls the chainstay forward, which rotates the 'missing link' and applies extension force to the shock. The implication being that this is what happens when riding.
What you are ignoring, is that when the rest of the linkage is connected, it opposes that extension force on the shock. E.g. forward force on the axle puts the seat stay link in compression, rotating the upper rocker link forwards, pushing down on the link that connects the rocker to the shock, therefore applying a compressive force to the shock (almost completely counteracting the extension force on the shock by the 'missing link').
If you apply a force at the axle that is perpendicular to the axle path, then there is no resultant force on the shock.
With your system, because of the axle path, there is a slight overall extension force on the shock due to pedalling, especially near top out. The magnitude of this force is dependent on the axle path, which is reflected in Anti-Squat calculations already discussed above.
Please don't simply respond by saying "you don't understand" or "but this suspension is different". I happen to have a pretty good grasp on this topic, and I can assure you there is absolutely nothing going on in your suspension kinematics that is beyond the AS and LR facts listed above. The laws of physics still apply.
I hope you take the time to read and understand the theory behind planar linkages. As you say, it's not simple. But it really does make a lot of sense when you fully understand it.
Furthermore once you start coming round (hopefully) to understanding the theory a bit better, you will recognise that our obsession with AS and LR (and AR) is justified, as these parameters fully describe the kinematics of a suspension system.
If you're not prepared to open your mind to the many well-informed people trying to explain it to you, then I give up. It's clear that you're set in your ways and not prepared to learn something new. Hopefully that's not true.
Regards,
Hugh McLeay
Is this saying I'm great? no, it's me saying I didn't just pull this out of my ass. Why and who would I be fooling?
No, I don't use linkage. Why? I did play with it to see what the buzz was about. It's just a little amateurish and clunky for my personal tastes. I write my own software for each application. I've written finite element code, a linkage program is pretty easy to whip up. This insures absolute accuracy with out worrying about assumptions or built in defaults that a canned program must have. They all do.
You are correct. Once my bikes are available, they will be measured. Competitors can and will buy them. Until then, are you really gonna call vrocks' self admittedly bad approximation facts? Seriously, as an engineer? c'mon now, call them what they are, a pretty iffy guess. No more, no less.
So, you have gone to great length to tell me all my stuff is bunk. Tell me what a very high AS bike rides like. Of the value you and Vrock suggest my bike is. Vrock wrote a very detailed report of how evil it would be. harsh at the top, on and on. Yet, in real life, it does none of that.
Who got it wrong? You, vrock or me? Why doesn't the bike behave the way your analysis predicts? Is it even possible that you're missing something? Vrock told me nothing would surprise him. Do you feel the same? Of course, you do not need to believe me when I say it rides like that. That's why I'm getting everyone to test it, just like you would, right?
Maybe you don't respect RC and his opinion. He's certainly not right about everything, but the man's been around and ridden everything under the sun. Do you think he just can't feel anything when he rides? Or is he just lying. It rides like shit and he wants to fool his readers? He might not be right about everything, but I doubt he would make the bold claims he did if the bike rode anywhere NEAR what you guys claim it should ride like :
“Does the impossible; pedals like a hardtail and delivers a plush ride over the bumps-without levers or electronics”.
”The Missing Link delivers the goods. Compared to the current crop of carbon superbikes, the Tantrum Meltdown performs well on the downs-essential for any 160-millimeter trail bike-and its pedaling action is better than all of them”.
He's not the only one saying this.
In the coming months, there will be more and more of these online and in print. Not to mention demo rides at eurobike and interbike. And then the Tantrum demo tour, sorry, US only this year.
They will all say the same thing. The suspension performs exactly as I claim.
So, where is the disconnect. Am I bending the laws of physics, or are you guys analysis flawed. What are you missing? A couple serious questions:
1) for the amount of AS you claim my bike has, is it possible to fully extend the rear and keep it there, as if solid, until the climb effort decreases?
Vrock has claimed no, it cannot. But yet is does. With no bobbing or relaxing into the travel on the dead spot lik a high AS bike. Why i this. How does your analysis explain this?
2) do you believe, that when in the fully extended position, essentially locked out on smooth ground, that the suspension will instantly react to a bump and immediately go back to full extension? Vrock does not.
But yet, it does. Yes, it does. So where is the hole in the analysis? How is this happening?
These are absolutely serious questions. you are telling me you have facts, but they seem to fly in the face of the actual facts. The bike rides like I say. How is this? One guy actually told me that my bike might do what I say, but not for the reasons I say. Cracked me up. I replied "then I'm the luckiest guy since Newton'.
Like I somehow managed to due a shitload of math and modeling, all completely wrong, but got the right answer.
So, the engineer in you has to say, what am I missing? Let's for a moment, forgot our disagreements about how we analyse linkages ( I will always love free body diagrams. The building blocks of physics). Let's make an engineering assumption that the suspension performs as I say and that videos are not fake.
Are you gong to still trust your analysis, like the engineer that designed the o-rings on the space shuttle:? (it's not rocket surgery), or are you going to be an engineer and figure out which mistake you made? Because even if I don't have a clue, made a complete mess of the math, the bike rides the way me and others describe. When that report keeps getting repeated, how will you respond?
I do appreciate your engineering effort. But your not getting the complete picture by your own math, but still representing absolute fact and authority. Is that engineering?
Oh wait a sec, I'm an engineer, of course it's absolute fact and authority
one review is just that, one review. There are many people that know and trust that reviewer. There will be more. Maybe even somebody you know and trust.
Some of them might be worried about losing ad revenue, there is that theory. I think a contract to that effect might have even surfaced somewhere. But I'm not buying any ads at the moment, have made no promise to.
No, with any commercial organization, websites, magazines, etc, I've noticed for the most part a total lack of objectivity when it comes to bike reviews. Bikes that I have ridden that I know pedal like crap, or the suspension is like a jackhammer, but they downplay it or claim things to the opposite. I expect they will have generally positive things to say, and I don't blame it on some secret conspiracy, but I do find that there really is no objectivity anymore. Literally every bike review comes across claiming that the bike reviewed is the best ever, or has no faults.
So where is it, where is the technical explanation for your Wunderwaffe? All you do all the time is dodge and claim you know it all and us peasants know nothing at all.
I call woo.
I haven't been reading the long winded arguments, but I do have a new graphic design. Enjoy!
If there's anybody I trust to be transparent and honest, it's the guy who wrote a two page diatribe on how we should be more accepting of the bike industries' BS minutes before the announcement of SRAM's Eagle 12speed went live. Do you think he got paid per word, or per line?
What I don't get is that you could shut up everyone once and for all by providing the accurate analysis of your suspension design. Why not just do it and put money where your mouth is?
FWIW: the scientific approach is that you deliver facts supporting your hypothesis that others then peer review and try to argue against. If nobody can come up with a good argument against your data then your hypothesis is accepted. And in the science world you have to make all steps of your analysis public. So if you use self written code then you need to provide it as well. I know that you might not want to work scientifically here, but then why bother arguing at all? Just send you demo bikes to MBA and others and you will get glowing reviews and all dentists will buy your bikes.
That and strip the hideous graphics off.
Hi Rider,
First things first. I will not publish any accurate numbers as to the physical location of the various pivots, etc.Who does that, anyway? Nobody that I know of, correct me if I'm wrong. Even as Hugh mentioned above, once they're available, people can and will measure it. Then they will put the coordinates into their analysis and backward engineer what's happening.
What I have done is publish and explain, here and on the website, what is happening and what is felt by the rider. these are the people that want to know what the bike feels like. What were my motives and design goals and how it results in a better ride. From my point of view, "wheel rate" is a much more relevant parameter to the layperson. It is literally, how stiff it is. How much force does it take to compress the suspension. This is what counts.
Who cares what the LR is? Engineers, nobody else. Do you think more than 10-20% of the riding population can even tell you want a LR or AS is? i also like to bring up free body diagrams. They don't like that either. Their physics professors would be ashamed.
The scientific approach that you're referring to is not in play here regarding peer review. I'm not trying to get my article published in a journal on how I invented cold fusion so I can get funding to play at the university. Oh, and by the way, I am WAYYYYY past the hypothesis stage. Right? I'm riding it!!!. This isn't a theoretical argument. Rather the opposite, some of the pundits are hypothesizing and apparently angry that their hypothesis doesn't reflect reality. That's when an engineer goes back to the drawing board and figures out what the missed.
Provide my code? Why don't I just publish the entire solidworkls model? Does ?Ferrari as Chevy for peer review? Does Trek ask DW?
Why am I here? Somebody started a thread and a friend said, "hey, people have questions about your bike", so here I am. What will eventually happen, as has in other forums, is that the people intent on creating their own analysis to bolster their own theory of design. will run out of arguments. There are only so many. of both.
Then a more reasonable logical discussion can ensue, with a little less of the typical internet "you're a liar!!" "Bullshit" and the like. Open minded people, engineers and non engineers alike, can ask questions, get answers, discuss if the advantages are something they would find useful, etc.
Because that's a bigger issue. This bike does things no other bike can do.
Did I accomplish it in a conventional way? of course not!!! That's not possible!
I do kinda like that, but if it wins, you didn't follow the rules. Sorry, you just worked for freeI haven't been reading the long winded arguments, but I do have a new graphic design. Enjoy!
HAHA, that's a whole NOTHER shitstorm....all new graphics for production models
You can start with this www.tantrumcycles.com. It's much easier than digging thru this thread. Give it a read or two. I'll be happy to answer any questions. Oh, the LR is 2.5 to 1 and the AS varies from 0 to 100 (kidding)
That is true. The fact is, while there is a certain tension between journalists and manufactures, we are all in it together. A lot of us have known each other for a long time. So i think there's a little bit of a desire to not be too much of a dick. I think though, they always let it be known when they don't like something, like "it's a little scary going downhill, so it's more for the XC crowd". Like kinda let 'em down easy.
There's a website that sends me reviews of bikes (not this one or the one that did my review, yet). I think they do a decent job. They have a consistent test area and, while they never say a bike is shit, I have seen some come out pretty poorly rated. You know what, the bottom line is, bikes ARE pretty good and I would guess 50% of riders wouldn't be able to appreciate a lot of the extra performance some bikes offer, mine included.
I found what Jm_ said to be true when I was bike shopping recently. Reviewers blow smoke up the asses associated with the hands that feed them. The only way I could differentiate between designs was to hop on them and demo them.
I'd demo a Tantrum and offer my 2 cents on its ride despite my skepticism.
I'd demo a Tantrum and offer my 2 cents on its ride despite my skepticism.
Toshi, (and the rest) not to make you name names, but, are there any mags or sites, you feel ARE more objective?
soon