[OGRipper]

The dw-link website has the following quote: "Squat is the result of internal chassis forces that can cause a rear suspension to stiffen, extend, or compress during acceleration."

Is it true that squat can result from a rear suspension extending? Got an example? I thought squat was a force that causes compression...?

And forgive me, but the axle path curve on the dw-link website seems awfully similar to a single pivot - a constant gradual arc. Is that just an over-simplified rendering and is the axle path a different shape (e.g., more like a vpp design)?

Been hearing good things about the new iron horse dw bikes and just checking it out. Thanks.

 

[Jm_]

Jack= extending of suspension, effectively raises the spring weight because bumps must overcome the force of the jacking

squat=squatting of suspension, suspension "sags" far into it's travel and bumps are not longer absorbed well due to the higher spring rate at that point in the travel.

 

[zedro]

in car speak, isnt the opposite of squat (as far as accelerating) called 'hop'?

i find the DW-Link explanation about axle paths to be a bit strange considering dw has vocalized on here that axle path is a very minor aspect. I believe the main MO about the linkage is how it translates the rear axle acceleration into the chassis, keeping it stable, and less to do with the consequential axle path of the linkage.

 

[dw]

Squat is a generic term that relates to suspension movement under acceleration. Pro-squat for example, is a term used to describe forced suspension compression. Anti-squat is a term that is used to describe some suspension system's resistance to suspension compression under powered acceleration.

RE: Axle path,
Axle path by itself is useless to know. Axle path in realtion to key components and the environment is critical.


The dw-link.com site is in the middle of a major overhaul and the new site includes a glossary. Yeeehaaaahh!!

Later on

Dave

 

[dw]

And forgive me, but the axle path curve on the dw-link website seems awfully similar to a single pivot - a constant gradual arc. Is that just an over-simplified rendering and is the axle path a different shape (e.g., more like a vpp design)?

Been hearing good things about the new iron horse dw bikes and just checking it out. Thanks.

Noo need to ask for forgivness!

The picture on the dw-link website, and all diagrams were made in adobe illustrator. They arent really accurate representations of the actual system.

A single pivot would have a constant arc. The dw-link, unlike many other 4-bar type systems, has a varying radius axle path. The arc of the axle path is not constant at all, therefore very different than a single pivot. Tuning this unique axle path in relation to the chassis and environment allows me to develop suspension frames that acclerate incredibly efficiently, much more so than any other frames that we are aware of. Proof is in the pudding though! So far the prototypes have podiumed all but 1 World Cup and Norba mens DH this year. Thats a pretty damn accomplished record for a bike that has not even been shown to the public yet. So far so good I guess!

Dave

 

[dropmachine]

You sexy bastard I love it when you talk dirty.

 

[OGRipper]

Now these are the kind of responses that makes RM such a great resource. Thanks Zedro and DW!

DW, what do you mean by tuning in relation to the environment?

And maybe you've explained this before, but other than the linkage configuration, how is the dw design different from vpp? Both seem to use a full rear triangle and two links to provide a varied axle path and a tuneable shock rate. Am I opening a big can of worms here?

 

[dw]

You can find a TON of information on this in the archives on this site. Its been explained quite a few times by yours truly.

In actuality, dw-link and VPP are about as far opposite to each other as is possible for 2 suspension designs. Just about the only similarity between the 2 systems is that the typical arrangements use somewhat short links and a triangulated coupler link.

Once all patents are issued there will be a lot more talking abou this. Until then I have to be a little guarded about what I can say.

Dave

 

[dw]

You sexy bastard I love it when you talk dirty.

:love:

LOL!

 

[dw]

in car speak, isnt the opposite of squat (as far as accelerating) called 'hop'?

i find the DW-Link explanation about axle paths to be a bit strange considering dw has vocalized on here that axle path is a very minor aspect. I believe the main MO about the linkage is how it translates the rear axle acceleration into the chassis, keeping it stable, and less to do with the consequential axle path of the linkage.

The terms are identical and well documented in automotive vehicle dynamics, but generally automotive systems are typically much simpler to analyze and refine.

As far as the explaination of dw-link, I think you are most likely missing/ misunderstanding some parts of the explainations, but thats OK. Like I said before, axle path by itself is pretty meaningless because it is only one parameter of a multi variable equation.

dw

 

[zedro]

As far as the explaination of dw-link, I think you are most likely missing/ misunderstanding some parts of the explainations, but thats OK. Like I said before, axle path by itself is pretty meaningless because it is only one parameter of a multi variable equation.

dw

its just from what i remember, i scanned it a long time ago, was just commenting on what you chose to say. Way to keep things vague

i am aware of the important mechanisms, variables and relationships in linkage design, just not at your level of expertise....

 

[thaflyinfatman]

Like I said before, axle path by itself is pretty meaningless because it is only one parameter of a multi variable equation.

dw

Alright... if you had two bikes with identical axle paths (and identical shock rates/ratios/centres of mass), but the linkages/methods used to get these identicalities (I'm sure that's not a word but you get the drift) were different (eg mounted in a different place, blah blah), could there be any difference in their response under acceleration?

 

[davod]

http://www.tonyfoale.com/

The book on there (motorbike chassis design) was recommended to me by Dave W. After reading it, I can recommend it as well, but with a bit less authority (or assurance that the info is accutate...)
It costs a bit though (US$60 -ish), so it depends if you want to buy it or not.

 

[TWISTED]

Alright... if you had two bikes with identical axle paths (and identical shock rates/ratios/centres of mass), but the linkages/methods used to get these identicalities (I'm sure that's not a word but you get the drift) were different (eg mounted in a different place, blah blah), could there be any difference in their response under acceleration?

I think you are refering to the execution of what DW is doing concerning the acceleration to squat relationship. There have been three different versions of prototype IH DW DH bikes so you know there is plenty of testing and refinement going on before the production versions will be made.

I'm eager to try one out myself and look forward to other DW link bikes soon to come.

 

[OGRipper]

Quote: "Alright... if you had two bikes with identical axle paths (and identical shock rates/ratios/centres of mass), but the linkages/methods used to get these identicalities (I'm sure that's not a word but you get the drift) were different (eg mounted in a different place, blah blah), could there be any difference in their response under acceleration?"

I could be wrong about all or some of this, but the two bikes you describe chould have totally different responses to pedaling (and feedback from bumps, and braking performance, and the shock rates could be completely different). The axle path is only part of the equation. "Acceleration" also depends on the position of the cranks relative to the rear wheel and the linkage configuration.

So for example, you could probably build a bike with an FSR rear end that has the same axle path as a single pivot bike like a Bullit. They would be very different bikes.

 

[Westy]

Squat: What you do when you have to crap
Sag: What happens to double D's over time.
Jack: What you do when you can't get a hold of some fresh double D's.

 

[HRDTLBRO]

Haha!

 

[thaflyinfatman]

Quote: "Alright... if you had two bikes with identical axle paths (and identical shock rates/ratios/centres of mass), but the linkages/methods used to get these identicalities (I'm sure that's not a word but you get the drift) were different (eg mounted in a different place, blah blah), could there be any difference in their response under acceleration?"

I could be wrong about all or some of this, but the two bikes you describe chould have totally different responses to pedaling (and feedback from bumps, and braking performance, and the shock rates could be completely different). The axle path is only part of the equation. "Acceleration" also depends on the position of the cranks relative to the rear wheel and the linkage configuration.

So for example, you could probably build a bike with an FSR rear end that has the same axle path as a single pivot bike like a Bullit. They would be very different bikes.

I mentioned "if the shock rates were identical", and I mean only in positive acceleration (pedalling), ie disregard braking

 

[Nately27]

Regarding Tony Foale and his book. Sport Rider (the motorcycle magazine) used his software in the latest issue to analyze the suspension kinematics of the Honda unit pro-link suspension. I'm bout to put my order in for his book though, and with two references like that, it should be good. With the exchange rates its frickin expensive, 125 shipped to the US. jeez...