[monkeyfcuker]

Has anyone read this article in the May issue of Dirt mag? It's the first one in a series looking at the specifics of DH bikes, this months began looking at the differences and similarities between F1 cars and the DH bikes we ride. Got to admit I found it really interesting and can't wait to read the next article, just wondered what people on here thought about it especially the more techie guys, (DW, Socket etc) anything you disagree with?

Cheers Mike.

 

[Rhubarb]

I miss Dirt mag.

 

[SPDR]

I've been sceptical about the whole K9 thing since the start but enough people seem to love what they're doing for me to give them another chance. Lets just say, I'm interested to read what he writes.

I'm also interested to learn what dw has to say about what he writes. (If he would ever be drawn to comment) I'm certainly interested to see what he'd have to say on the K9 LW link patent

 

[klunky]

Im sceptical too. Having read posts on other forums (not by Luis) but others from K9 I dont think I would want to have anything to do with them.
LA link? haha

 

[TKCastle]

So when is the KERS system going to be available for my dh bike?

 

[iRider]

Dave has a fanboy!!!!!!!!!!!!! :biggrin:

 

[w00dy]

K9 LW link patent

Looks like a forward arc to me. Nothing you couldn't achieve with a low single pivot.

 

[BKQuill]

So when is the KERS system going to be available for my dh bike?

Or the dual diffusers

 

[ebarker9]

So when is the KERS system going to be available for my dh bike?

The question is...are you willing to become anorexic enough to offset the weight difference?

 

[Steve M]

I've been sceptical about the whole K9 thing since the start but enough people seem to love what they're doing for me to give them another chance. Lets just say, I'm interested to read what he writes.

I'm also interested to learn what dw has to say about what he writes. (If he would ever be drawn to comment) I'm certainly interested to see what he'd have to say on the K9 LW link patent

Link doesn't work?

Anyway I spoke to Luis for a little while at Fort William in 07... some of his theories were off the mark back then, though he did seem very interested and involved in doing real world testing on a lot of stuff, so I'd be interested to see what he actually wrote. We don't get Dirt till like 2 months late down here, anyone wanna scan the article and email it to me? steve at rotorburn.com if you can. For anyone worrying about copyright issues, I won't redistribute, and I buy every issue of the mag anyway so they won't be losing sales

 

[Gridds]

For those that the link doesn't work, The patent page says this:

Abstract:
A suspension system for a bicycle comprising a rear wheel mounting member (4), a chassis member (2), an upper linkage (6) pivotally connected to the rear wheel mounting member and the chassis member at first (Pl) and second (P2) pivot points respectively and a lower linkage (8) pivotally connected to the rear wheel mounting member and the chassis member at third (P3) and fourth (P4) pivot points respectively thereby forming a four-bar linkage system, characterised in that the length of the upper linkage (6) between the first and second pivot point and the length of the lower linkage (8) between the third and fourth pivot points are both are greater than the separation between the second and fourth pivot points. An embodiment includes a jockey wheel or idler pulley which provides a tensioned portion of chain which passes through the instant centre of rotation (IC).

So as I understand it, if the jockey wheel or idler pulley passes through the instant centre of rotation then, yeah - a single pivot should do the same job in terms of axle path? Yes, no??

 

[Pslide]

Have spoken with someone who has ridden one of the prototype bikes in anger, and who is unbiased, and he was pretty blown away with the quality of the suspension. Over medium sized hits and chatter it felt unbelievably good. Could be down to the F1 style shock tuning they've probably done on it (sorry, not sure which shock was on it), but nonetheless, this guy seems to know a thing or two about making suspension work!

 

[dw]

I've been sceptical about the whole K9 thing since the start but enough people seem to love what they're doing for me to give them another chance. Lets just say, I'm interested to read what he writes.

I'm also interested to learn what dw has to say about what he writes. (If he would ever be drawn to comment) I'm certainly interested to see what he'd have to say on the K9 LW link patent

Given that the same basic layout, including the idler wheel is shown and discussed in the already granted dw-link patents, I find it hard to believe that the LA design will get anywhere beyond "pending" in the patent office. I'm not too concerned about it either way..

 

[dw]

Link doesn't work?

Anyway I spoke to Luis for a little while at Fort William in 07... some of his theories were off the mark back then, though he did seem very interested and involved in doing real world testing on a lot of stuff, so I'd be interested to see what he actually wrote. We don't get Dirt till like 2 months late down here, anyone wanna scan the article and email it to me? steve at rotorburn.com if you can. For anyone worrying about copyright issues, I won't redistribute, and I buy every issue of the mag anyway so they won't be losing sales

Any time I read anything about chainlines passing through instant centers, the credibility meter definitely pegs somewhere around zero..

 

[Gridds]

Hmm. Interesting. Forgive my ignorance but can you explain what an 'instant centre' actually is please Dave or anyone? Is it the 'virtual pivot point' or what? Cheers

 

[dw]

Hmm. Interesting. Forgive my ignorance but can you explain what an 'instant centre' actually is please Dave or anyone? Is it the 'virtual pivot point' or what? Cheers

hit the search function, I've written ad-nauseum on the subject on this board. You could also read one of the dw-link patents 7128329 would give you a detailed breakdown.

 

[djamgils]

Some info on K9
http://dirtmag.co.uk/news/category/dirt-team/k-nine-industries-global-exclusive/dirt-1234738.html

For me it seems like it that people use Instant Center, Instant Force Center and Virtual Rotation Point as a different name for the same things. Or are there differences between them? simply put I thought it was the crossing of the 2 lines that go trough the 2 linkages. (that is defined as point 24 "instant force center" in DW's patent)

Any time I read anything about chainlines passing through instant centers, the credibility meter definitely pegs somewhere around zero..

whats wrong with chainlines passing trough instant centers? Isn't it just semantics/definitions? My interpretation is that the try to have point 24 and 26 close to each other.
For me it seems that with the placement of the pulley you can change point 26 "chain force vector and driving force vector intersection point" and thus change the amount of anti squat.

for reference

 

[MMike]

Will dw take the bait?

Let's wait and watch!

 

[xy9ine]

who actually does the patent illustrations, and why do they all look like they were drawn in 1892?

 

[Steve M]

Any time I read anything about chainlines passing through instant centers, the credibility meter definitely pegs somewhere around zero..

While I'm inclined to agree from a technical standpoint, thorough real world testing with real world data acquisition equipment has plenty of potential to net you a bike that rides as well or better than a bike that was designed entirely based on theoretical calculations without the real-world data to support it. Might not be perfect, but some of the nicest-riding bikes have come from technically "flawed"/imperfect designs too. The same can DEFINITELY be said of suspension tuning... some dampers are great on paper but suck on the track, some (like Motion Control) are hideously crude but actually work quite well.

 

[Steve M]

Some info on K9
http://dirtmag.co.uk/news/category/dirt-team/k-nine-industries-global-exclusive/dirt-1234738.html

For me it seems like it that people use Instant Center, Instant Force Center and Virtual Rotation Point as a different name for the same things. Or are there differences between them? simply put I thought it was the crossing of the 2 lines that go trough the 2 linkages. (that is defined as point 24 "instant force center" in DW's patent)


whats wrong with chainlines passing trough instant centers? Isn't it just semantics/definitions? My interpretation is that the try to have point 24 and 26 close to each other.
For me it seems that with the placement of the pulley you can change point 26 "chain force vector and driving force vector intersection point" and thus change the amount of anti squat.

for reference

Chainlines passing through instant centres doesn't mean anything; I think you're getting confused between the IC and the centre of curvature (which is linked to the IC and its movement), which isn't point 26 on that drawing. Point 26 is the intersection of the chain force line and the impulsion force line.

 

[dw]

While I'm inclined to agree from a technical standpoint, thorough real world testing with real world data acquisition equipment has plenty of potential to net you a bike that rides as well or better than a bike that was designed entirely based on theoretical calculations without the real-world data to support it. Might not be perfect, but some of the nicest-riding bikes have come from technically "flawed"/imperfect designs too. The same can DEFINITELY be said of suspension tuning... some dampers are great on paper but suck on the track, some (like Motion Control) are hideously crude but actually work quite well.

I'm not totally sure what your response had to do with my post, but I agree with you. For sure, empirical testing can definitely net good results. I'd guess that the vast majority of the suspension bikes on the market have been developed through empirical testing only. It just takes forever, and you are never really sure what you are going to get, or how to improve it. I prefer math + testing.

 

[MMike]

I'm not totally sure what your response had to do with my post, but for sure, empirical testing can definitely net good results. I'd guess that the vast majority of the suspension bikes on the market have been developed through empirical testing only.

"These aren't the droids you're looking for"
"These aren't the droids we're looking for"

 

[dw]

who actually does the patent illustrations, and why do they all look like they were drawn in 1892?

There is a "code" of how patent illustrations are supposed to look.

 

[dw]

lots of words and a picture

I think Steve basically summed it up.

It's been inaccurately suggested many times by many people that somehow if you align the chain force line with the instant center, you achieve some sort of magically awesome performance.

I've written about the hows and whys of this in detail on Ridemonkey and MTBR between 2000 and 2005, less recently, why keep repeating myself. I am sure you can find the info through a search.

 

[MMike]

I've written about the hows and whys of this in detail on Ridemonkey and MTBR between 2000 and 2005, less recently, why keep repeating myself. I am sure you can find the info through a search.

And how IS that book coming along?

 

[jonKranked]

That drawing was probably done by an orangutan on PCP.

 

[dw]

And how IS that book coming along?

I kind of gave up on it a few years ago, it's just so time consuming to finish something that long and technical, and also, I decided that there are things that I would really like to include, but that I don't want to share with other people quite yet.

 

[SPDR]

Given that the same basic layout, including the idler wheel is shown and discussed in the already granted dw-link patents, I find it hard to believe that the LA design will get anywhere beyond "pending" in the patent office. I'm not too concerned about it either way..

Are you saying (which is what I've thought all along) that the "LA Link" is essentially using dw link technology but making it work with a rearward axle path and therefore needs an idler?

Oh and I have suspected that the awesome ride and grip are more to do with the axle path and (mostly) the CCDB than any inherent genius in the execution.

Just seems like rich kids playing the old "bullsh1t baffles brains" game to me.
But then I know nothing and a lot of people seem to think Luis is a genius and the bike rides amazingly. They certainly seem to be trying to put something into the sport and for that they should be applauded.

 

[Arkayne]

 

[dw]

Are you saying (which is what I've thought all along) that the "LA Link" is essentially using dw link technology but making it work with a rearward axle path and therefore needs an idler?

Oh and I have suspected that the awesome ride and grip are more to do with the axle path and (mostly) the CCDB than any inherent genius in the execution.

Just seems like rich kids playing the old "bullsh1t baffles brains" game to me.
But then I know nothing and a lot of people seem to think Luis is a genius and the bike rides amazingly. They certainly seem to be trying to put something into the sport and for that they should be applauded.

The only thing that I'm saying is that if you read the dw-link portfolio, the use of a swingarm mounted idler on a short four bar design is clearly discussed, and that the granting dw-link portfolio predates that application date by a long time.

 

[Spokompton]

There is a "code" of how patent illustrations are supposed to look.

Not really. Most of the standards are set to make sure that it copies well, and is easy to read. Other than that, there are MANY ways to draw a patent figure.

Here's what they require. I'm sure you've seen this before.
No where does it mention, must be drawn in 1905 patent style!

http://www.uspto.gov/web/offices/pac/doc/general/drawing.htm

 

[gemini2k]

While I'm inclined to agree from a technical standpoint, thorough real world testing with real world data acquisition equipment has plenty of potential to net you a bike that rides as well or better than a bike that was designed entirely based on theoretical calculations without the real-world data to support it.

"Theory doesn't matter, only experimental results" -Shuji Nakamura

 

[MobileChernobyl]

Cool another rearward axle path for people to drool over lol, and an idler to increase the length of the chain as well.

The axle path doesn't change the shape of the wheel hitting the rock.

 

[dirtdigger]

Cool another rearward axle path for people to drool over lol, and an idler to increase the length of the chain as well.

The axle path doesn't change the shape of the wheel hitting the rock.

yes your right about the shape of the wheel but what does change is the distance the main frame has traveled buy the time the wheel has got over the rock.

 

[RayB]

I prefer math + testing.

Words to live by.

 

[Steve M]

I'm not totally sure what your response had to do with my post, but I agree with you. For sure, empirical testing can definitely net good results. I'd guess that the vast majority of the suspension bikes on the market have been developed through empirical testing only. It just takes forever, and you are never really sure what you are going to get, or how to improve it. I prefer math + testing.

Sorry, assumed you were aware - the K9 guys are very big on the data acquisition stuff, as well as damper testing and whatnot. That's why it's relevant.

Danny: if you were to define the 4 bar linkage of a bike, kinematically, as having bars labeled 1, 2, 3 and 4, where:
1 = the front triangle, can be modelled as a straight line between whichever two pivots are attached to it
2 = the lower link, modelled as a straight line between the pivot attached to the front triangle, and the pivot attached to the swingarm
3 = the swingarm (or seatstay on an FSR style bike), defined by a TRIANGLE whose vertices (corners) were the two pivots by which it is attached to the two links which join it to the front triangle, and the rear axle
4 = the upper link, which again can be modelled as a straight line between the pivot attaching it to the swingarm, and the pivot attaching it to the front triangle

The shock can be driven between any two of these bars, and has no bearing on the axle path, so we'll ignore that for the moment. A 4 bar linkage has 2 instant centres from the two pairs of links, but only the IC formed by lines drawn through links 2 and 4 is of any interest to us, since we're concerned with axle path relative to front triangle. The IC (fully termed as the Instantaneous Centre of Zero Velocity) is the point about which the entirety of bar 3 (the swingarm) is rotating/moving tangent to at a given time. This means that if you drew motion tangent lines from anywhere on the swingarm, they would always be concentric to the IC (ie normal to a line drawn from whichever point you choose, to the IC). I'm fairly sure you already know this anyway. However, because the IC moves by definition, where it is AT ANY SINGLE POINT in the travel doesn't actually give you any information on the axle path besides a tangent path at an instantaneous point in the movement of the linkage.

If you plot the IC at one point in the travel, then move the axle a minute increment, the IC will have shifted, as will the axle. If you plot a line between the IC and the axle at both these points in the travel, the location where the two lines intersect will approximate your centre of curvature. Mathematically, as the increment of travel/movement decreases to zero, the accuracy of the CC increases - calculus is the only way to obtain an exact location. The CC is different to the IC in three major ways:

1. It is relevant ONLY to one single point on the swingarm (the only point we care about is the axle). The centre of curvature for the axle is not the same as the centre of curvature for any other point on the swingarm.
2. The CC defines a radius of curvature for the axle path, which the IC does not do.
3. For any given axle path, the position and migration path of the CC (which can move, by the way, it is not fixed) will always be identical. The IC positions can vary infinitely along the normal to the axle path, for any given axle path. This is why it's possible to produce two linkages with very different IC locations/movements, that have an identical axle path - such as an FSR bike and an equivalent single pivot (where the IC is fixed at the pivot) for example. By the same token, two bikes can have identical IC locations at one or several points in the travel, yet significantly different axle paths. If the IC migration relative to Bar 1 (as defined above) is zero, then the IC is the CC, and both are fixed.

Hope this clarifies things.

 

[dw]

Sorry, assumed you were aware - the K9 guys are very big on the data acquisition stuff, as well as damper testing and whatnot. That's why it's relevant.

Ah gotcha, no, I haven't paid one bit of attention really.

 

[dw]

Sorry Dave.

The K9 idler is not swingarm mounted, it's on a static frame mount attached to the seat tube

Either way, it's in there. No need to be sorry though!

 

[SPDR]

Just to stir things up a bit, here's a response from an insider at K9 about this thread

"The LA link is fully patented. Therefore it does not infringe on anything that DW has done.
As far as I know, the 4-bar linkage and roller system are both prior art; in other words, they've been around for ages, nobody can really claim to have invented them, nobody can put a patent on them.

And I'm not going to voice my opinions on DW's comment on the matter, or his suspension and bike designs.

Anyone that gets on a K9 will know its not a DW design.

Tambo"

From HERE

I know I'm stirring but it sounds like it could be a real meeting of minds if DW & K9 were to get together. If only there weren't a load of people stood around chanting fight fight, maybe something good could come of it.