# DW LINK vs. VPP? Same or is one better?



## MicroHuck (Jan 31, 2005)

They seem like they should act the same seeing as they both accomplish the same task.

Only difference being on uses a swing arm (VPP) to the shock mount and the other uses a rocker arm to the shock (DW-Link).

I would think DW-Ling has an advantage of having the weight of the shock lower.

Both companies claim the same results. More efficiency while maintaining perfect sensitivity to bumps.

Which one has the advantage? The DW-Link Iron horse frames are cheaper though, right? Is the only difference, PRICE?
Here's what the DW-LINK looks like on the 7point7 frame...

















VPP


----------



## Steve from JH (Dec 30, 2003)

On the DW link the upper link rotates clockwise along with the lower link. On the VPP the upper link rotates counter clockwise. That makes for very different effects.


----------



## .WestCoastHucker. (Jan 14, 2004)

the DW link looks more like a modified walking beam...... (kona with a urt)


----------



## The Kadvang (Jul 25, 2004)

.WestCoastHucker. said:


> the DW link looks more like a modified walking beam...... (kona with a urt)


its definitly not a urt


----------



## .WestCoastHucker. (Jan 14, 2004)

The Kadvang said:


> its definitly not a urt


looks like a unified rear triangle to me, the rear triangle is all one piece right? i don't see any pivots except for the links...


----------



## WheelieMan (Jan 19, 2004)

.WestCoastHucker. said:


> looks like a unified rear triangle to me, the rear triangle is all one piece right? i don't see any pivots except for the links...


No, a URT design has the bb attached to the swingarm.


----------



## sriracha (Jun 23, 2004)

looks like a cross between a VPP and a Canfield.


----------



## .WestCoastHucker. (Jan 14, 2004)

WheelieMan said:


> No, a URT design has the bb attached to the swingarm.


either way, still similar to the walking beam, the one piece rear would act as the seatstays and the links would act like very short chainstays......


----------



## The Kadvang (Jul 25, 2004)

.WestCoastHucker. said:


> looks like a unified rear triangle to me, the rear triangle is all one piece right? i don't see any pivots except for the links...


on a URT the BB pivots on/with the swingarm,


----------



## .WestCoastHucker. (Jan 14, 2004)

The Kadvang said:


> on a URT the BB pivots on/with the swingarm,


look up a couple of posts, bonehead....


----------



## binary visions (Jan 18, 2004)

None of the above, really. They both have a solid rear triangle connected by two links, but they have very different approaches to the same goal (pedal efficiency).

You should really try to ride both to see for yourself. The VPP theory is that an S-shaped axle path causes chain tension to be constantly pulling the suspension towards one point in the travel.

DW claims his system tries to counter-act the forces and weight that the rider imparts on the suspension - so, it doesn't just pedal well, it actually resists your weight acting on the suspension. I believe Go-Ride mapped the suspension path as moving back and up, then fairly straight up, then a bit forwards towards the end of the travel. Never seen that any other place, though.

That's the theory, anyway! The reviews from the DW-link bikes thus far have been absolutely glowing (at least, I haven't read a bad one). VPP seems to be a love or hate thing - either the riders love it, or they hate the dead feeling of the suspension.

Hopefully DW will correct me if I'm wrong but that's what I've been reading


----------



## .WestCoastHucker. (Jan 14, 2004)

binary visions said:


> ...... it (the DW link) actually resists your weight acting on the suspension......


doesn't the spring do the same thing?


----------



## Speedub.Nate (Dec 31, 2003)

.WestCoastHucker. said:


> doesn't the spring do the same thing?


I wouldn't say the dw-link resists weight -- that incorrectly imparts that pedaling forces act counter to suspension compression.

Instead, it is very neutral to rider input throughout the range of travel. Unlike VPP, which stiffens under hard pedaling, the rider's pedaling efforts are mostly "invisible" to the dw-link: suspension compliance is unchanged regardless if the bike is coasting or being mashed furiously.

The net effect is the dw-link has exceptional small bump compliance, has zero appreciable pedal feedback (no interruption to spin as the suspension cycles), and is extremely resistant to bob without relying on platform valving.


----------



## MicroHuck (Jan 31, 2005)

Speedub.Nate said:


> I wouldn't say the dw-link resists weight -- that incorrectly imparts that pedaling forces act counter to suspension compression.
> 
> Instead, it is very neutral to rider input throughout the range of travel. Unlike VPP, which stiffens under hard pedaling, the rider's pedaling efforts are mostly "invisible" to the dw-link: suspension compliance is unchanged regardless if the bike is coasting or being mashed furiously.
> 
> The net effect is the dw-link has exceptional small bump compliance, has zero appreciable pedal feedback (no interruption to spin as the suspension cycles), and is extremely resistant to bob without relying on platform valving.


...Thus, DW > VPP?...

Maybe the DW has more advantages than I thought. Sounds pretty sweet. Funny how we don't hear much about the Iron Horse frames, even though the DW may be way better than other similar priced frames out there.

Anyone know where/how to get Iron horse frames (only)? I can't seem to find any frames for sale, or even how much they go for...


----------



## The Kadvang (Jul 25, 2004)

go-ride has the sunday and 7. framsets for sale


----------



## Speedub.Nate (Dec 31, 2003)

MicroHuck said:


> ...Thus, DW > VPP?...


That's my firm belief on a Hollowpont vs. Blur level, but I haven't ridden the 7Point or Sunday to make the comparison of the big-travel bikes.

My understanding is that the characteristics of the dw-link bikes remain constant throughout the lineup (the Sunday uses an even further refined dw-linkage), but I don't know what characteristics of the VPP bikes change when we get into 6-8" of travel.

AFAIK, the IH framesets available are the Sunday Factory (US built) and pretty soon the Azure Factory (XC race version of the dw-link). I didn't know about that 7Point at Go-Ride.

To get [/B]my MkIII frame[/B], I bought a complete bike and parted it out. A bit of work, but a more economical way to build to my own spec.


----------



## TheSherpa (Jan 15, 2004)

I had a Blur, and ride a V10. I'd take DWlink anyday.


----------



## Speedub.Nate (Dec 31, 2003)

MicroHuck said:


> Funny how we don't hear much about the Iron Horse frames, even though the DW may be way better than other similar priced frames out there.


I think a lot of it boils down to marketing and advertising budgets.

The dw-link on the Hollowpoint remained essentially unchanged from mid-2002 through 2004. The MkIII frame is such a radically changed frame that it had to generate some buzz, but although the dw-link on that bike has been tweaked in some subtle and not-so-subtle ways, I don't expect it to perform dramatically differently than my Hollowpoint (i.e. other than the stiffer construction, my butt may not be able to tell the difference).

The version that showed up on the Indy Fab Tungsten Electrode is a somewhat similar short-travel version of what we're seeing on the Sunday.

I think the fact that Giant replicated the dw-link so closely with its Maestro suspension, it's bound to give the dw-link some needed credibility, and hopefully a extra-large dose of karma -- it's apparant Dave Weagle has been working on this design for a long time!

My guess is, with four bikes featuring the dw-link this season, covering XC, all-mountain, freeride and downhill, IH is going to get noticed and the bikes will speak for themselves. We'll see, though -- the bigger marketing budget often trumps the superior technology, and not just in the bike industry.


----------



## DeJean (Feb 4, 2005)

I believe we're missing the point here
VPP is not only designed to pedal well. 
It's also -and primarily- designed around the axle path.

I had an M1 prior to my M3. And yes it pedals better, but the main improvement is in how much faster it rolls. The rougher the terrain, the mor the M3 excels. As the wheel arches to the back a bit, the bike and rider can keep more of their momentum when going through a hit. 
This effect is real, very noticeable and very effective. I get to pedal on sections where I used to hang on. So forget the internet jibjab: it DOES NOT stiffen when pedalling. See Pic below for an example of the sort of terrain i'm talking about

The CoG of the M3 is the lowest I've ever felt on a bike. The shock is right on top of the BB and leaning forward, I don't believe it can sit much lower without hanging it under the down tube.
I never tested a DWlink bike, so I can't judge.

this is the sort of terrain i'm talking about:


----------



## COmtbiker12 (Jan 12, 2004)

MicroHuck said:


> ...Thus, DW > VPP?...
> 
> Maybe the DW has more advantages than I thought. Sounds pretty sweet. Funny how we don't hear much about the Iron Horse frames, even though the DW may be way better than other similar priced frames out there.
> 
> Anyone know where/how to get Iron horse frames (only)? I can't seem to find any frames for sale, or even how much they go for...


I think the point is... DW = Different than VPP. They each have their own advantages. (I haven't had the privilege of riding a DW yet though.  )


----------



## binary visions (Jan 18, 2004)

.WestCoastHucker. said:


> doesn't the spring do the same thing?


Yes, but wouldn't you rather not have to over-spring your bike so that the suspension is free to do its thing (absorbing bumps) rather than relying on a heavier spring to counteract pedalling/went transfer?



Speedub.Nate said:


> I wouldn't say the dw-link resists weight -- that incorrectly imparts that pedaling forces act counter to suspension compression.


After you said that, I went back to look at DW's old posts.


_dw said:


> Plain and simple, dw-link counteracts mass transfer and pedaling forces during acceleration so that your rear suspension can freely absorb small and large bumps, while at the same time giving very little pedal feedback, and having excellent braking charateristics.





_dw said:


> In comparison to your Blur (which is still a very nice bike), the dw-link will also have more anti-squat, just enough to totally counteract mass transfer, but not enough to cause suspension extension.


Does "counteracts mass transfer" mean something else than what I understand it to mean? I understand it to mean that when you pedal, it resists the weight transfer of the rider compressing the suspension.


----------



## flymybike (Jan 6, 2004)

binary visions said:


> Does "counteracts mass transfer" mean something else than what I understand it to mean? I understand it to mean that when you pedal, it resists the weight transfer of the rider compressing the suspension.


Spot on.


----------



## jtc (Feb 3, 2004)

*Here's some great info!!!*

I haven't ridden the VPP or the Iron Horse, but I have a Karpiel Disco Volante (love it!) and I've ridden two different Canfield models (sooo sweeet!) Heres some info that pre-dates the VPP and the DW-Link both by at least two years if not three.
http://www.canfieldbrothers.com/Suspension.htm


----------



## binary visions (Jan 18, 2004)

flymybike said:


> Spot on.


 I wish they had the :thumb: smilie here.

So pedalling forces do, to a certain extent, counter suspension compression. I guess the trick is to make it resistant enough to keep your weight from compressing it, but not so resistant to keep it from absorbing bumps, eh? Which would allow you to run a lighter spring, which allows the bike to be super compliant on small bumps.

MicroHuck, if you review _dw's posting history, there's a lot of suspension discussion.

http://forums.mtbr.com/showthread.php?t=4575
http://forums.mtbr.com/showthread.php?t=57727

All good, educational reading


----------



## zedro (Jan 12, 2004)

binary visions said:


> So pedalling forces do, to a certain extent, counter suspension compression.


 the magic word is 'anti-squat'. Its the same basic principal why low single pivots like to squat through every stroke, and high single pivots want to extend or jack (called 'axle-hop' in car terms). This extension can also be used to counteract the bodies downward forve on the bike through the pedal stroke as well, which is what he's talking about. The acceleration of the rear wheel vs the frame and how the two interact via the linkage is the major contributor to 'bob' performance.

So its a combination of anti-squat, chain tensions through the travel, IPs, suspension tuning etc that make the bike pedal and behave over bumps. Every suspension type will have different combinations, so yes, the links do matter.

And they are nothing like walking beams...


----------



## binary visions (Jan 18, 2004)

zedro said:


> the magic word is 'anti-squat'.


Right, I actually knew what the term was (believe it or not ), just didn't want to chuck one more term into the mix.

I forgot to mention, but there's an extremely good description of what exactly the VPP design does and why it's different from DW-link in that first thread link I posted.


----------



## bighitboy (May 16, 2004)

there is a great article on suspension types in the newest MBA magazine, but its mba so i dont know how much of it is true?  dave weagle knows his stuff, i am looking forward to getting a IH sunday


----------



## TheSherpa (Jan 15, 2004)

bighitboy said:


> there is a great article on suspension types in the newest MBA magazine, but its mba so i dont know how much of it is true?  dave weagle knows his stuff, i am looking forward to getting a IH sunday


Its all BS.


----------



## Speedub.Nate (Dec 31, 2003)

binary visions said:


> I forgot to mention, but there's an extremely good description of what exactly the VPP design does and why it's different from DW-link in that first thread link I posted.


Thanks for pulling those posts up. I'm hoping Dave Weagle jumps in and posts some comments.

In that first post you linked to, Dave wrote: _"The Hollowpoint's dw-link setup develops a tuned amount of anti-squat starting as soon as the suspension begins to compress. At 0 inches of travel through 2 inches of travel, the bikes basically develop 100% anti squat through a wide range of gears. *This means that as you accelerate, the suspension action is left unimpeded to react to to terrain*."_

This is what I'd like him to clarify. My interpretation of this, and other stuff he's written (not to mention two years riding a Hollowpoint) is that 100% anti-squat is another way of saying the pedaling input forces have zero impact on the suspension -- it is neither compressive nor extending, just neutral.


----------



## Speedub.Nate (Dec 31, 2003)

bighitboy said:


> there is a great article on suspension types in the newest MBA magazine, but its mba so i dont know how much of it is true?  dave weagle knows his stuff, i am looking forward to getting a IH sunday


I don't trust MBA for much in the way of technical writing. They'll rehash whatever marketing speak they can muster, but they've botched too many writeups and talked out of both sides of their mouths too often to be taken seriously.

There also appears to be some bad blood between MBA and either IH or DW. The other mags have given IH a fairer shake, but unfortunately they aren't great technical reviewers, either.

I know, I know, I sound like a conspiracy theorist. Bring on the German bike mags.


----------



## Steve from JH (Dec 30, 2003)

*100% antisquat*



Speedub.Nate said:


> Thanks for pulling those posts up. I'm hoping Dave Weagle jumps in and posts some comments.
> 
> In that first post you linked to, Dave wrote: _"The Hollowpoint's dw-link setup develops a tuned amount of anti-squat starting as soon as the suspension begins to compress. At 0 inches of travel through 2 inches of travel, the bikes basically develop 100% anti squat through a wide range of gears. *This means that as you accelerate, the suspension action is left unimpeded to react to to terrain*."_
> 
> This is what I'd like him to clarify. My interpretation of this, and other stuff he's written (not to mention two years riding a Hollowpoint) is that 100% anti-squat is another way of saying the pedaling input forces have zero impact on the suspension -- it is neither compressive nor extending, just neutral.


As I understand it, in the motorsports industry the standard opinion is about dead opposite to DW's. The suspension will be "unimpeded to react to the terrain" when you have 0% antisquat. Antisquat is an extending torque that combats the tendency of the vehicle to squat in the rear when accelerating. Having both a compressing and an extending force acting on the rear suspension at once (100% antisquat does just that) binds up and restricts the rear suspension.

I've attached a diagram of a motorcycle with more than 100% antisquat. I don't have a good one stored with exactly 100%. If the point identified as P of M, where the chain line intersects the swingarm line, were to lie on the lower of the two slanted lines running forward from the rear contact point, then you would have 100% antisquat.


----------



## Andrewpalooza (Dec 7, 2004)

Speedub.Nate said:


> I don't trust MBA for much in the way of technical writing. They'll rehash whatever marketing speak they can muster, but they've botched too many writeups and talked out of both sides of their mouths too often to be taken seriously.
> 
> There also appears to be some bad blood between MBA and either IH or DW. The other mags have given IH a fairer shake, but unfortunately they aren't great technical reviewers, either.
> 
> I know, I know, I sound like a conspiracy theorist. Bring on the German bike mags.


I've seen MBA contradict itself in the same issue before. The issue at hand was lockout. At first they said pedal bob wasn't that bad, lockout was for idiots, then they sung its praises 30 pages later.

Their article about FSR/VPP/DW/Lawill all being the same did bring up a good point though -- they all have a similar design. The axle and brakes are mounted on a bar that is seperated from the frame by other links. All of those have at least that in common.

Personally I have my favorites:

FSR for XC
Single Pivot for DH/FR

In both cases, I just like the feel of the bike. FSR pedals really well too.


----------



## Steve from JH (Dec 30, 2003)

*More on anti-squat*

There are other theoretical problems with setting up a bike with 100% anti-squat. The percentage calculation is based on the assumption that the bike is accelerating steadily from a constant force. That never happens in cycling. Instead we have a sine-wave pattern of fluctuating force. At the beginning of a pedal stroke, when the force begins to increase, the bike is still decelerating. What happens is that the curve of the deceleration changes, going from increasing to decreasing. At this stage 100% anti-squat is way too much for efficiency.

And speaking of efficiency, the motorcycle text from which I got the diagram in my previous post says that maximum energy efficiency does not occur with 100% anti-squat (even assuming a steady acceleration). That's because the load shift will raise the front while leaving the rear unchanged. The net effect is that the center of mass is raised. If you have just enough squat in the rear to counter the raising of the front so that the center of mass stays level, then you have maximum energy efficiency.

Another consideration is traction. Because the anti-squat takes effect before the weight shift to the rear from acceleration occurs, the rear wheel is pushed down into the ground. This gives good bite, but it amounts to stiffening the spring, so it's bad for bump compliance. It's probably best to have around 100% anti-squat when climbing the very steepest stuff. But the DW-link bikes are set up with 100% in the middle gears. They have way more down in the granny with the largest cogs. On the other hand Horst type bikes like the Turners have about 100% when in their lowest gears.


----------



## _dw (Jan 20, 2004)

Steve from JH said:


> As I understand it, in the motorsports industry the standard opinion is about dead opposite to DW's.


Without getting into another classic "dw suspension tutorial" I can assure you that that is an incorrect statement. The analysis that I use, and infomation used to describe the systems is 100% accurate, and agreed upon by the common text and people that I have dealt with in the motorcycle industry. I had the great opportunity to sit with Tony Foale last fall, and his analysis and nomenclature agree with mine fully.



Steve from JH said:


> The suspension will be "unimpeded to react to the terrain" when you have 0% antisquat.


incorrect statement, actually the reverse is true. since squat of any type only occurs under acceleration (positive or negative) 0% anti squat would allow the suspension to compress, therefore loading the suspension. I think that it is pretty obvious to any rider that your suspension will absorb small bumps easier when the suspension is not compressed versus compressed. Its gets deeper than that, but you should be able to see the reality of it.



Steve from JH said:


> Antisquat is an extending torque that combats the tendency of the vehicle to squat in the rear when accelerating.


correct statement, sort of. Anti squat is not a toque, its a resultant force, otherwise correct.



Steve from JH said:


> Having both a compressing and an extending force acting on the rear suspension at once (100% antisquat does just that) binds up and restricts the rear suspension.


incorrect statement



Steve from JH said:


> I've attached a diagram of a motorcycle with more than 100% antisquat. I don't have a good one stored with exactly 100%. If the point identified as P of M, where the chain line intersects the swingarm line, were to lie on the lower of the two slanted lines running forward from the rear contact point, then you would have 100% antisquat.


yes, you would, at that instantaneous point in the suspension travel. The anti squat amount will drop rapidly in this suspension layout.

Hope this clears some things up


----------



## _dw (Jan 20, 2004)

Steve from JH said:


> There are other theoretical problems with setting up a bike with 100% anti-squat.


I agree somewhat. Thats why I invented dw-link. The flip side to consider is that a suspension using a constant 100% anti-squat will outperform one using a constant 0% anti-squat no matter what.



Steve from JH said:


> The percentage calculation is based on the assumption that the bike is accelerating steadily from a constant force. That never happens in cycling. Instead we have a sine-wave pattern of fluctuating force. At the beginning of a pedal stroke, when the force begins to increase, the bike is still decelerating. What happens is that the curve of the deceleration changes, going from increasing to decreasing. At this stage 100% anti-squat is way too much for efficiency.


Squat is a function of acceleration. As the acceleration varies, the squat amount varies. Its a non-issue.



Steve from JH said:


> And speaking of efficiency, the motorcycle text from which I got the diagram in my previous post says that maximum energy efficiency does not occur with 100% anti-squat (even assuming a steady acceleration). That's because the load shift will raise the front while leaving the rear unchanged. The net effect is that the center of mass is raised. If you have just enough squat in the rear to counter the raising of the front so that the center of mass stays level, then you have maximum energy efficiency.


You are misinterpreting your text.



Steve from JH said:


> Another consideration is traction. Because the anti-squat takes effect before the weight shift to the rear from acceleration occurs, the rear wheel is pushed down into the ground. This gives good bite, but it amounts to stiffening the spring, so it's bad for bump compliance.


No, not really. I see what you are thinking, but you are missing a key point. Perform a simple dynamic analysis and you will see how the ofrces actaully lay out. The wheel force is the same either way, just the suspension ride height and actuation force changes.



Steve from JH said:


> It's probably best to have around 100% anti-squat when climbing the very steepest stuff. But the DW-link bikes are set up with 100% in the middle gears. They have way more down in the granny with the largest cogs. On the other hand Horst type bikes like the Turners have about 100% when in their lowest gears.


I can tell for sure that you have not mapped out the dw-link bikes, or you are not understanding how they work. These statements are just not true for any of these bikes. Sorry to call you out, its not my intention to make you look bad or anything like that, I just have to be honest.

All the best

Dave


----------



## -bb- (Feb 3, 2005)

TheSherpa said:


> I had a Blur, and ride a V10. I'd take DWlink anyday.


For what it is worth....

1st I had a VPP. THen I bought a DW link, giving me one of each.
When I needed a new bike, having owned one of each, I bought another DW link, not a VPP.


----------



## Steve from JH (Dec 30, 2003)

How to prove what the common opinion of suspension experts is? Obviously readers of MBTR are more likely to believe you than me. And I don't even count myself as a suspension expert.

For what it's worth I just typed in "anti-squat" at the top of my screen and got a response from AOL's search engine. Choosing the first entry that looked helpful on the first page I found the following statement:So to answer the question as to what increasing anti-squat will do. It can assist in incautiously creating forward bite. But just for an instant, and then will go away. This might seem like it will help rear grip, and is some specific cases it will. However, this instantaneous transfer (geometric stiffening) comes at a cost of decreasing the rear compliance of the car which in the long run , can often hurt rear bite.​ That "geometric stiffening" is what I was talking about. With 0% the spring remains unstiffened. Now if it compressed a lot from the acceleration, not much travel would be left, and the shock rate might be higher, and those would be undesirable results. But the small movement produced by puny human acceleration should leave the spring free to react the same under power as coasting.


----------



## TheSherpa (Jan 15, 2004)

Steve from JH said:


> How to prove what the common opinion of suspension experts is? Obviously readers of MBTR are more likely to believe you than me. And I don't even count myself as a suspension expert.
> 
> For what it's worth I just typed in "anti-squat" at the top of my screen and got a response from AOL's search engine. Choosing the first entry that looked helpful on the first page I found the following statement:So to answer the question as to what increasing anti-squat will do. It can assist in incautiously creating forward bite. But just for an instant, and then will go away. This might seem like it will help rear grip, and is some specific cases it will. However, this instantaneous transfer (geometric stiffening) comes at a cost of decreasing the rear compliance of the car which in the long run , can often hurt rear bite.​ That "geometric stiffening" is what I was talking about. With 0% the spring remains unstiffened. Now if it compressed a lot from the acceleration, not much travel would be left, and the shock rate might be higher, and those would be undesirable results. But the small movement produced by puny human acceleration should leave the spring free to react the same under power as coasting.


Comparing apples to oranges?

You need to get off your high-horse and quit disagreeing with dw, who obviously understands this far more than you do.


----------



## Steve from JH (Dec 30, 2003)

_dw said:


> Squat is a function of acceleration. As the acceleration varies, the squat amount varies. Its a non-issue.


During pedaling there is alternate negative and positive acceleration. The negative acceleration can be thought of as acting at the center of mass and therefore produces no load shift either way. The pedal stroke starts increasing in force while the bike is still decelerating and there is no squat or jack from the deceleration.. So the extending anti-squat force initially has no accelerational load shift to work against.



> You are misinterpreting your text.


 Here is the text:We can imagine a particular case in which there is zero jacking; this would only come about when the front end extension is exactly equal to the rear end compression, or rather, to state this in scientific terms, when the two axes have equal vertical stiffness in opposition to the force of traction.​This would give rise to a rotation of the motorcycle around its center of gravity without any variation in center of gravity height.​ The course described by the center of gravity when the motorcycle is under acceleration will be practically horizontal in this case, *which means minimum waste of energy.*​


> I can tell for sure that you have not mapped out the dw-link bikes, or you are not understanding how they work. These statements are just not true for any of these bikes. Sorry to call you out, its not my intention to make you look bad or anything like that, I just have to be honest.


It's hard to map using my primitive Linkage freeware and not knowing exactly where the pivots are. The best I can come up with is that the Mark III, in both middle and small ring, at a sag of either 30 or 40 mm, keeps the chain line running through the center of curvature throughout the first half or so of travel. That's an interesting achievement but I don't understand how it's an advantage any more than keeping the chainline through the IC a la Ellsworth.

I calculate the anti-squat at about 135% using a center of mass at 1 meter high. That's about where my crotch is when I'm sitting on my bike. To get 100% anti-squat the CM would have to be up by my chest.

I'm not worried about being made to look bad. I'm old enough to be your grandfather and nothing much bothers me and I couldn't look much worse.


----------



## Steve from JH (Dec 30, 2003)

TheSherpa said:


> Comparing apples to oranges?
> 
> You need to get off your high-horse and quit disagreeing with dw, who obviously understands this far more than you do.


Are you referring to the high BB on my Id?

What I was just doing was quoting people who disagree with DW.

By the way I would definitely choose a dw-link over a vpp.


----------



## TheSherpa (Jan 15, 2004)

Steve from JH said:


> Are you referring to the high BB on my Id?
> 
> What I was just doing was quoting people who disagree with DW.
> 
> By the way I would definitely choose a dw-link over a vpp.


No, motorcycles and cars to bikes. It seems every single DW thread that pops up, either here or on RM, you have something negative to say or some disagreement that always gets shot down by DW or zedro.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> Having both a compressing and an extending force acting on the rear suspension at once (100% antisquat does just that) binds up and restricts the rear suspension.


I haven't been following the suspension debates like I used to but this statement doesn't make any sense to me.

If you have 100% antisquat, acceleration induced squat is exactly countered by the linkage geometry and the net force due to acceleration at the rear wheel is zero. Now add in a bump force and the net is exactly equal to that bump force. This is the situation where the suspension is most free to react to the trail under acceleration conditions.

With more than 100% antisquat, the bump force would have to be greater than the net excess antisquat to activate the suspension. With less than 100% antisquat, the spring is effectively preloaded and again less free to react to bumps. In this case, you'd increase the spring rate to keep the bike from riding too low in its travel, making the bike less compliant even while coasting.

I think this is what _dw is saying. Are you saying there is another contributing force that i'm neglecting?


----------



## andy f (Jan 13, 2004)

TheSherpa said:


> You need to get off your high-horse and quit disagreeing with dw, who obviously understands this far more than you do.


That's an idiotic statement. Progress is made only when people have the courage to challenge conventional wisdom. Steve might not be correct in this case but telling him to simply defer to authority is wrong. It's a good thing Galileo didn't listen to the naysayers when he came to the conclusion that the sun was the center of the solar system. Steve's no Galileo nor does he claim to be but he is sincere in his desire to understand suspension dynamics and is not on any sort of stupid crusade to discredit _dw.


----------



## jzt (Apr 20, 2004)

DeJean said:


> I believe we're missing the point here
> VPP is not only designed to pedal well.
> It's also -and primarily- designed around the axle path.
> 
> ...


hi i've been following this discussion in earnest, and hearing all this impressive physics & mechanics stuff. I'm just wondering though, if DW provides the same benefits as VPP as stated by DeJean? (That is, the backward-ish arc of the rear wheel goign thru its travel, which provides a smoother ride over big square-edged bumps) And if so, to a greater/lesser extent, or pretty much the same? Thanks!


----------



## Steve from JH (Dec 30, 2003)

andy f said:


> I haven't been following the suspension debates like I used to but this statement doesn't make any sense to me.
> 
> If you have 100% antisquat, acceleration induced squat is exactly countered by the linkage geometry and the net force due to acceleration at the rear wheel is zero. Now add in a bump force and the net is exactly equal to that bump force. This is the situation where the suspension is most free to react to the trail under acceleration conditions.
> 
> ...


What I'm saying is the same argument used to justify floating brakes. Typically a monopivot will have close to 100% anti-lift, which is the same thing as 100% anti-squat but with the forces reversed. It's calculated the same way but of course there's no chain line to consider. The position of the actual pivot or of the IC is used.

So with a typical monopivot when you apply only the rear brake, the load shift to the front from deceleration is more or less countered by the compressing resultant force from the brake torque. This is supposed to make the rear end less compliant to bumps. Hence the desirability of a floating brake which can lower the anti-lift percentage down to near zero. The rear end will then extend and many people confuse this with brake "jacking". But because the shock is freely reacting to forces acting only on the center of mass and not to forces created by the geometry of the linkage, traction is supposed to be better.

Turn this around and it should apply equally to pedal acceleration.

In any case none of these arguments are mine. They're standard, regardless of what DW says.

I posted this and some other stuff over on the What Bike to Buy forum in the thread where you were asking about the dw-link.


----------



## TheSherpa (Jan 15, 2004)

andy f said:


> That's an idiotic statement. Progress is made only when people have the courage to challenge conventional wisdom. Steve might not be correct in this case but telling him to simply defer to authority is wrong. It's a good thing Galileo didn't listen to the naysayers when he came to the conclusion that the sun was the center of the solar system. Steve's no Galileo nor does he claim to be but he is sincere in his desire to understand suspension dynamics and is not on any sort of stupid crusade to discredit _dw.


Your the idiot and obviously didn't understand what i was saying. This whole dw vs. VPP gets brought up ALL THE TIME, here and RM. Steve always comes in and says something negative about DW-link all the time. Oh and i think Copernicus was better than Galileo.


----------



## derby (Jan 12, 2004)

*There is no "industry standard"*



Steve from JH said:


> What I'm saying is the same argument used to justify floating brakes. Typically a monopivot will have close to 100% anti-lift, which is the same thing as 100% anti-squat but with the forces reversed. It's calculated the same way but of course there's no chain line to consider. The position of the actual pivot or of the IC is used.
> 
> So with a typical monopivot when you apply only the rear brake, the load shift to the front from deceleration is more or less countered by the compressing resultant force from the brake torque. This is supposed to make the rear end less compliant to bumps. Hence the desirability of a floating brake which can lower the anti-lift percentage down to near zero. The rear end will then extend and many people confuse this with brake "jacking". But because the shock is freely reacting to forces acting only on the center of mass and not to forces created by the geometry of the linkage, traction is supposed to be better.
> 
> ...


Don't believe everything you read.

Even the great designer, engineer, racer, and writer Tony Foele may have a great following and respect. Not he nor any other popular writer of vehicle dynamic theory is an "industry standard". There are no formal classes, schools, degrees, or government regulations in vehicle dynamic theory (except government crash test ratings). There is no industry standard. There are many theories.

The implementation and testing of theory is what best confirms a theory and establishes practice. And correction and improvements to established practice still evolves with greater experience.

Go test ride a DW-Link, VPP and any other examples of theory put to practice. I have. And DW's suspension clearly works best in the widest range of travel, seated and standing, in smooth or rough terrain. If his knowledge, theory, and language is whacky then his designs are very lucky, because they work noticeably better than any other bicycle suspension designs.

BTW, for shorter travel, less than 5-inch travel, a classic Horst AMP style design link works second best. For more than 5 inches VPP likely works second best to DW's designs.

Monopivots and similar pedaling ICT's, or I-drives, Mavericks, NRS, and other design fashions have more losses in overall balance in efficiencies. Although platform damping or falling rate damping greatly improves the pedaling imbalances for most of them.

- ray


----------



## Steve from JH (Dec 30, 2003)

derby said:


> There is no industry standard. There are many theories.


I simply meant that the theory "more anti-squat = less rear compliance" is a commonplace. To prove this, as I posted above, I basically chose at random an article from a search for "anti-squat" that contained the following:So to answer the question as to what increasing anti-squat will do. It can assist in incautiously creating forward bite. But just for an instant, and then will go away. This might seem like it will help rear grip, and is some specific cases it will. However, this instantaneous transfer (geometric stiffening) comes at a cost of *decreasing the rear compliance* of the car which in the long run , can often hurt rear bite.​So I was one for one in finding confirmatory theories.



> Go test ride a DW-Link, VPP and any other examples of theory put to practice. I have. And DW's suspension clearly works best in the widest range of travel, seated and standing, in smooth or rough terrain. If his knowledge, theory, and language is whacky then his designs are very lucky, because they work noticeably better than any other bicycle suspension designs.


The only problem here is that I have heard your reviews of the Truth and Id, among others, and I don't agree with a word of them.


----------



## zedro (Jan 12, 2004)

Steve from JH said:


> I simply meant that the theory "more anti-squat = less rear compliance" is a commonplace. To prove this, as I posted above, I basically chose at random an article from a search for "anti-squat" that contained the following:....


 yeah, articles always know what they are talking about, especially magazines like MBA for example......

besides, you may not even be interpreting the article correctly anyways, because if you were using much higher than 100% anti-squat (ie. "more"), of course it would intefere with compliance (notice they mentioned tire bite? that sorta alludes to that scenario).

There was a time when you actually took out a physics book Steve and looked at the little arrows instead of falling into apparent dogma. If we replaced the missleading term '100% anti-squat' with 'neutral' or 'forces at equilibrium', i doubt we'd be having this conversation. Or to put it another way, do you really believe making the bike consistantly squat under each power stroke makes the suspension more compliant? i think the answers obvious to anyone without throwing equations around.


----------



## sriracha (Jun 23, 2004)

what i keep wondering is, how does the dw link remain pedal effecient without relying on chain tension or a platform shock.
if it does rely on chain tension, then wouldn't it be similar to a vpp design, in terms of bump compliance?
if it doesn't rely on chain tension or spv, then how does it resist pedal induced bob?


----------



## zedro (Jan 12, 2004)

sriracha said:


> what i keep wondering is, how does the dw link remain pedal effecient without relying on chain tension or a platform shock.
> if it does rely on chain tension, then wouldn't it be similar to a vpp design, in terms of bump compliance?
> if it doesn't rely on chain tension or spv, then how does it resist pedal induced bob?


 its the way the linkage transfers the acceleration forces of the wheel to the frame, the same reason suspensions can behave so badly as well


----------



## Steve from JH (Dec 30, 2003)

zedro said:


> yeah, articles always know what they are talking about, especially magazines like MBA for example......
> 
> besides, you may not even be interpreting the article correctly anyways, because if you were using much higher than 100% anti-squat (ie. "more"), of course it would intefere with compliance (notice they mentioned tire bite? that sorta alludes to that scenario).
> 
> There was a time when you actually took out a physics book Steve and looked at the little arrows instead of falling into apparent dogma. If we replaced the missleading term '100% anti-squat' with 'neutral' or 'forces at equilibrium', i doubt we'd be having this conversation. Or to put it another way, do you really believe making the bike consistantly squat under each power stroke makes the suspension more compliant? i think the answers obvious to anyone without throwing equations around.


You like floating brakes, right? What floaters typically do (they can be set up to do just about anything) is reduce the compressing force on the rear that is countering the load shift to the front. Result: the rear extends with each application of the brakes but is supposed to have better compliance.

You can find the notion that any amount of anti-squat above zero will reduce the rear compliance in RACE CAR VEHICLE DYNAMICS by the Millikens. Hardly MBA.


----------



## TheSherpa (Jan 15, 2004)

Steve from JH said:


> I could give you a very long version of this but I won't. *I've argued at length with DW on MTBR and on Ridemonkey. The guy rubs me the wrong way more than Tony Ellsworth ever could. I've given up trying to discuss things with him or to analyze his designs. He intentionally won't publish accurate pictures or diagrams that show where the pivots really are. Nor will he explain his theories. He claims, however, that his bikes are the most efficient (where have I heard that?) and moreover that only he of all people on Earth has actually figured out bicyle kinematics*.
> 
> To show how exasperating it was to argue with him I'll give one sample. On Ridemonkey he stated that if the chainline intersected the swingarm line anywhere ahead of the rear axle the bike would always have extending torque. I countered by saying that if the point of intersection was below the ground (theoretically possible) then the torque would be compressing. I referred to a motorcyle text by Cocco of Aprilia motorcycle company. He responded by citing a page number from that text and saying that a diagram on that page supported his point. Well, I own the book and the diagram indisputably supports my point not his.
> *
> ...


So, in laymans terms, your out to prove Dave wrong with motorcycle textbooks?


----------



## j6105 (Apr 10, 2004)

the cool thing about FSR is that is 100% active all the time which gives crazy performance

Pedaling is good, but not as good as the VPP's i have ridden--- however the pedal feedback and rough sections are noticibly worse on a VPP.

The suspension on a VPP almost doesn't activate over bumps, but that still doesn't make up for the comment above that the M1 is way slower than the M3. I don't really understand that because FSR may feel slower because it moves and sucks up every bump, but in reality it gives you the ability to stay in control going crazy fast. 

What really gets me off is not dissecting this crap on the internet, but riding the bikes and deciding. As of now, specialized demo suspension is the best i have ever felt, but I am more than eager to ride a sunday that is properly set up (NEVER test ride at bike shops, get a bros bike).


----------



## andy f (Jan 13, 2004)

TheSherpa said:


> Your the idiot and obviously didn't understand what i was saying. This whole dw vs. VPP gets brought up ALL THE TIME, here and RM. Steve always comes in and says something negative about DW-link all the time. Oh and i think Copernicus was better than Galileo.


The least you could do is spell "you're" correctly when calling someone an idiot. Also note that I called your statement idiotic, not you. That was intentional.

Steve isn't saying anything bad about the DW-link for personal reasons. He's just very interested in suspension dynamics and disagrees with the majority consensus around here. If Steve is wrong, his ideas need to be shot down with technical arguments rather than high school cheerleading taunts.


----------



## WheelieMan (Jan 19, 2004)

j6105 said:


> the cool thing about FSR is that is 100% active all the time which gives crazy performance


Define 100% active. I don't think you understand what is even being discussed here.

Specialized's minister of propaganda once again has another victim.


----------



## andy f (Jan 13, 2004)

TheSherpa said:


> So, in laymans terms, your out to prove Dave wrong with motorcycle textbooks?


In this thread _dw refers to his discussion with Tony Foale. It looks like he thinks motorcycle suspension dynamics are relevant as well.


----------



## sriracha (Jun 23, 2004)

zedro said:


> its the way the linkage transfers the acceleration forces of the wheel to the frame, the same reason suspensions can behave so badly as well


so horizontal links resist horizontal forces and vertical links resist vertical forces?


----------



## zedro (Jan 12, 2004)

Steve from JH said:


> You like floating brakes, right? What floaters typically do (they can be set up to do just about anything) is reduce the compressing force on the rear that is countering the load shift to the front. Result: the rear extends with each application of the brakes but is supposed to have better compliance.
> 
> You can find the notion that any amount of anti-squat above zero will reduce the rear compliance in RACE CAR VEHICLE DYNAMICS by the Millikens. Hardly MBA.


 floaters do alot more, half the equations is the mechanics (or relative motions) between the tire and the ground through the travel. Anyways, different topic, and i dont understand the point you are trying to make.

also, race car dynamics and bike dynamics arent the same (nor are the mechanical systems), and it sounds like its meant in our context that anti-squat above 100% reduces compliances, which is obvious if 100% is the ideal. You should ask an F1 driver if they like it if the car squats under acceleration.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> What I'm saying is the same argument used to justify floating brakes. Typically a monopivot will have close to 100% anti-lift, which is the same thing as 100% anti-squat but with the forces reversed. It's calculated the same way but of course there's no chain line to consider. The position of the actual pivot or of the IC is used.
> 
> So with a typical monopivot when you apply only the rear brake, the load shift to the front from deceleration is more or less countered by the compressing resultant force from the brake torque. This is supposed to make the rear end less compliant to bumps. Hence the desirability of a floating brake which can lower the anti-lift percentage down to near zero. The rear end will then extend and many people confuse this with brake "jacking". But because the shock is freely reacting to forces acting only on the center of mass and not to forces created by the geometry of the linkage, traction is supposed to be better.
> 
> ...


There has got to be more going on here because if there is exact cancellation between squat and antisquat (or lift/antilift) the net force is equal to the bump force and any motion of the suspension is going to be due to the bump alone. If that's the only factor at play then _dw and zedro are correct: 100% antisquat is the ideal situation.

If you're correct about 0% antisquat being ideal, you need to find some way to demonstrate that this results in an equilibrium situation in the presence of acceleration forces. Maybe you feel you already have but I don't see it.


----------



## zedro (Jan 12, 2004)

sriracha said:


> so horizontal links resist horizontal forces and vertical links resist vertical forces?


 well with the links by themselves thats effectively the principal in the most basic context mechanically, of course alot more complex when your looking at a multilink suspension system with a body of mass and accelerations and all that. But you have the right idea, its how and where the links transmit the forces, and that depens on their orientation to each other and to the masses and forces.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> You like floating brakes, right? What floaters typically do (they can be set up to do just about anything) is reduce the compressing force on the rear that is countering the load shift to the front. Result: the rear extends with each application of the brakes but is supposed to have better compliance.
> 
> You can find the notion that any amount of anti-squat above zero will reduce the rear compliance in RACE CAR VEHICLE DYNAMICS by the Millikens. Hardly MBA.


So now you've got me looking a suspension dynamics instead of rate adaptation algorithms for wireless communication networks. Great. Next thing you know i'm going to start doing the force diagrams and math.

I just found this excerpt from Tony Foale's book on his website. I may be taking things a bit out of context only having these few pages available but it appears that he's saying 100% antisquat throughout travel is the unrealizable ideal and the best we can do is go for 100% at sag while minimizing the deviation throughout the travel.


----------



## sriracha (Jun 23, 2004)

zedro said:


> well with the links by themselves thats effectively the principal in the most basic context mechanically, of course alot more complex when your looking at a multilink suspension system with a body of mass and accelerations and all that. But you have the right idea, its how and where the links transmit the forces, and that depens on their orientation to each other and to the masses and forces.


ok
so, when we pedal, the vertical force of the leg becomes part horizontal and part verticle, the specific amounts related to acceleration of the total mass. but when we are not pedalling, feet being stationary, our mass becomes a vertical force applied to the bottom bracket.
with the dw link, when the feet are stationary (creating verticle forces) the horizontal links rotate freely and provides supple suspension. and when pedalling the horizontal links resist the horizontal forces, but what happens to the verticle part of the pedalling force? doesn't this create some pedal induced suspension movement?
ahh, my head hurts.
i need to test ride one.


----------



## WheelieMan (Jan 19, 2004)

sriracha said:


> ok
> so, when we pedal, the vertical force of the leg becomes part horizontal and part verticle, the specific amounts related to acceleration of the total mass. but when we are not pedalling, feet being stationary, our mass becomes a vertical force applied to the bottom bracket.
> with the dw link, when the feet are stationary (creating verticle forces) the horizontal links rotate freely and provides supple suspension. and when pedalling the horizontal links resist the horizontal forces, but what happens to the verticle part of the pedalling force? doesn't this create some pedal induced suspension movement?
> ahh, my head hurts.
> i need to test ride one.


Ummm, not quite, you're overthinking.


----------



## Steve from JH (Dec 30, 2003)

andy f said:


> There has got to be more going on here because if there is exact cancellation between squat and antisquat (or lift/antilift) the net force is equal to the bump force and any motion of the suspension is going to be due to the bump alone. If that's the only factor at play then _dw and zedro are correct: 100% antisquat is the ideal situation.
> 
> If you're correct about 0% antisquat being ideal, you need to find some way to demonstrate that this results in an equilibrium situation in the presence of acceleration forces. Maybe you feel you already have but I don't see it.


First, I'm not saying 0% is ideal for designing a bike, I'm saying it's ideal for suspension compliance. By that I mean the suspension will react to the bump the same as if it were not under power.

Acceleration causes squat in exactly the same way scooting your body more to the rear would cause squat. If you hit a bump while coasting and scooting your butt, the shock would react to the bump as well as to the scooting, swallowing it up just as well as if you were not scooting. (Unless you ran clear out of travel.)

Any amount of anti-squat has a stiffening effect as far as compression is concerned. The suspension won't compress as much under power as when coasting. That is, it won't compress as much *from the bump*, not counting the compression from acceleration. The bump therefore will have more effect in blowing the bike off course vertically.


----------



## Steve from JH (Dec 30, 2003)

zedro said:


> floaters do alot more, half the equations is the mechanics (or relative motions) between the tire and the ground through the travel. Anyways, different topic, and i dont understand the point you are trying to make.
> 
> also, race car dynamics and bike dynamics arent the same (nor are the mechanical systems), and it sounds like its meant in our context that anti-squat above 100% reduces compliances, which is obvious if 100% is the ideal. You should ask an F1 driver if they like it if the car squats under acceleration.


What I'm saying about floaters is that 100% anti-lift is exactly analogous to 100% anti-squat except that the forces are in opposite directions. You don't like 100% anti-lift. I know that from reading your posts. You think floaters are a good idea. They reduce the percentage of anti-lift--sometimes clear down to zero.

It's my understanding that F1 cars typically have way less than 100% anti-squat. I received an e-mail from a racing engineer with Toyota back years ago when I first used the term "anti-squat". He said a race car was like a human or a bear--it's got to squat in order to go. He said a car with anywhere near 100% anti-squat would blow loose the rear end when accelerating out of a turn.

My motorcycle book, on the other hand, says racing cycles are often set up with more than 100% in order for the rear end to rise along with the front end. This is to keep the pitch angle of the chassis steady and the steering consistent.


----------



## TheSherpa (Jan 15, 2004)

andy f said:


> The least you could do is spell "you're" correctly when calling someone an idiot. Also note that I called your statement idiotic, not you. That was intentional.
> 
> Steve isn't saying anything bad about the DW-link for personal reasons. He's just very interested in suspension dynamics and disagrees with the majority consensus around here. If Steve is wrong, his ideas need to be shot down with technical arguments rather than high school cheerleading taunts.


Well, uh. 

How much different does the whole pedaling and lightweight being important in bikes skew the ideals of motorcycle tech?


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> First, I'm not saying 0% is ideal for designing a bike, I'm saying it's ideal for suspension compliance. By that I mean the suspension will react to the bump the same as if it were not under power.
> 
> Acceleration causes squat in exactly the same way scooting your body more to the rear would cause squat. If you hit a bump while coasting and scooting your butt, the shock would react to the bump as well as to the scooting, swallowing it up just as well as if you were not scooting. (Unless you ran clear out of travel.)
> 
> Any amount of anti-squat has a stiffening effect as far as compression is concerned. The suspension won't compress as much under power as when coasting. That is, it won't compress as much *from the bump*, not counting the compression from acceleration. The bump therefore will have more effect in blowing the bike off course vertically.


How can anti-squat cause stiffening if it is exactly cancelled by squat force? The net force in the absence of a bump in that case is zero, just as it is while coasting. The only time your statement could be correct is when anti-squat is greater than squat, leaving a net force to be overcome by the bump before it can activate the suspension.


----------



## andy f (Jan 13, 2004)

TheSherpa said:


> Well, uh.
> 
> How much different does the whole pedaling and lightweight being important in bikes skew the ideals of motorcycle tech?


It'll change what you need to do to achieve a good design but the same fundamental physical principles still apply to both.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> He said a car with anywhere near 100% anti-squat would blow loose the rear end when accelerating out of a turn.


Ah, traction. That part makes sense to me but it seems that with the puny amount of power humans generate, a bicycle shouldn't require much less than 100% to provide sufficient traction.


----------



## Steve from JH (Dec 30, 2003)

andy f said:


> How can anti-squat cause stiffening if it is exactly cancelled by squat force? The net force in the absence of a bump in that case is zero, just as it is while coasting. The only time your statement could be correct is when anti-squat is greater than squat, leaving *a net force to be overcome by the bump before it can activate the suspension*.


It's not a question of the bump not activating the suspension, it's a question of how much compression you would get. In the equilibrium condition, squat=anti-squat, the rear end behaves as though you had a heavier rider and a stiffer spring than you actually have. When the actual bump force reacts with the actual mass, the result is less suspension activity.


----------



## j6105 (Apr 10, 2004)

i know you were talking about 100% and 0% squatting crap........... i just stated FSR is 100% active....

do you need to call people out on the internet to make yourself feel better about your miserable existance?

S*** ain't propaganda........ treat yourself and ride a properly set up demo.


----------



## Tracerboy (Oct 13, 2002)

I own an M3, and I was able to ride around a bit on an IH Sunday Team. The IH pedals just as well as my M3 and handles very well. It felt a bit heavy on the front end; it was a bit hard to pull up and manual. Other than that, I felt that the two were comparable. If it's just VPP vs. DW, I don't think you're gonna make a bad decision either way. Just go for the frame that's going to suit your type of riding the best.


----------



## jzt (Apr 20, 2004)

how did the Sunday fare on the bumpy stuff? Was it as smooth as your M3 going over rocks, roots etc? I understand one of the key benefits of VPP is the wheel path where the initial travel sees the back wheel moving rearward when reacting to bumps, which gives a smoother feel as you cruise down rock gardens. Do the DW bikes perform similarly?


----------



## DeJean (Feb 4, 2005)

j6105 said:


> the cool thing about FSR is that is 100% active all the time which gives crazy performance
> 
> Pedaling is good, but not as good as the VPP's i have ridden--- however the pedal feedback and rough sections are noticibly worse on a VPP.
> 
> ...


Suspension not activating on a bump? have you actually ridden one? And was it set up correctly? This is very opposite to my personal experiences. You've seen the picture i posted? I pedal tru that terrain, how would that be possible if the suspension would be disabled?

As I put all parts of my M1 on the M3 and had a worldcup mechanic assist in the setup of the shock on both bikes, I think I can compare. I do not race, so i've not split times to compare.
What i can say is that the m3 handles the rough terrain in a better and more stable way than the M1, with the exact same parts. That it pedals better, specially thrugh the rough stuff. With a pedal induced lockout like you say, it would stutter whil pedalling. It is smoother whil pedalling the rough stuff than the M1 coasting over the same section.
I talked to Claudio Caluori, Ex Team BeOne. He owns an M3 as well and has the exact same findings.

Great that you're happy with your Demo, you made a good choice then. The bike may fit your style better, but I can't really believe your findings. No offense man.
Now back to DW-VPP


----------



## TheSherpa (Jan 15, 2004)

DeJean said:


> Suspension not activating on a bump? have you actually ridden one? And was it set up correctly? This is very opposite to my personal experiences. You've seen the picture i posted? I pedal tru that terrain, how would that be possible if the suspension would be disabled?
> 
> As I put all parts of my M1 on the M3 and had a worldcup mechanic assist in the setup of the shock on both bikes, I think I can compare. I do not race, so i've not split times to compare.
> What i can say is that the m3 handles the rough terrain in a better and more stable way than the M1, with the exact same parts. That it pedals better, specially thrugh the rough stuff. With a pedal induced lockout like you say, it would stutter whil pedalling. It is smoother whil pedalling the rough stuff than the M1 coasting over the same section.
> ...


He's just another child of the Specialized propaganda machine.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> It's not a question of the bump not activating the suspension, it's a question of how much compression you would get. In the equilibrium condition, squat=anti-squat, the rear end behaves as though you had a heavier rider and a stiffer spring than you actually have. When the actual bump force reacts with the actual mass, the result is less suspension activity.


I see no rhyme or reason to the argument you're presenting here. The equilibrium condition while coasting and the equilibrium condition when squat and anti-squat are balanced are exactly equivalent (net force = zero) with respect to how a bump force would activate the suspension unless there are other significant factors at play that you are neglecting to mention in this discussion.


----------



## sriracha (Jun 23, 2004)

sriracha said:


> but what happens to the verticle part of the pedalling force? doesn't this create some pedal induced suspension movement?


oh wait, i bet the vertical placement of the rear shock has something to do with all this.


----------



## WheelieMan (Jan 19, 2004)

j6105 said:


> i know you were talking about 100% and 0% squatting crap........... i just stated FSR is 100% active....
> 
> do you need to call people out on the internet to make yourself feel better about your miserable existance?
> 
> S*** ain't propaganda........ treat yourself and ride a properly set up demo.


Ok then, by that definition, the only bike I can think of that is NOT 100% active is the Specialized Epic. The suspension is designed to be locked out unless the suspension hits a bump.

VPP and DW designs are just as active as your Demo.


----------



## Tracerboy (Oct 13, 2002)

jzt said:


> how did the Sunday fare on the bumpy stuff? Was it as smooth as your M3 going over rocks, roots etc? I understand one of the key benefits of VPP is the wheel path where the initial travel sees the back wheel moving rearward when reacting to bumps, which gives a smoother feel as you cruise down rock gardens. Do the DW bikes perform similarly?


Well, the M3 has like 1-and-a-half inches more travel than the Sunday, so the M3 felt smoother; but the Sunday did feel a bit smoother than my Giant DH, which had 8.25 inches of travel. From my experience riding an M3 for a few months now, I think the real benefit of VPP is the pedalling. The bike "wanting to pedal over bumpy stuff because of the suspension design" is hype, IMO.

Take any given rear suspension design; we'll take VPP. Some will say that it's good and has it's benefits while others will say that VPP is just hype. My opinion.....VPP is a great design for a bike that has a lot of travel, like the M3. It gives great pedalling performance, while still giving you gobs of travel to get over the big stuff.


----------



## Steve from JH (Dec 30, 2003)

*reason and rhyme*



andy f said:


> I see no rhyme or reason to the argument you're presenting here. The equilibrium condition while coasting and the equilibrium condition when squat and anti-squat are balanced are exactly equivalent (net force = zero) with respect to how a bump force would activate the suspension unless there are other significant factors at play that you are neglecting to mention in this discussion.


Well I'm trying to use reason. Let's try it this way:

Imagine for the sake of simplicity that we have steady state acceleration on horizontal terrain with a linear spring shock and a constant leverage.

Now first consider the bike travelling slightly uphill at a constant velocity. The rider deliberately maintains exactly the same posture relative to the bike as if it were going horizontally. The gravitational force can be represented by a vector that unlike the horizontal situation will be slanting slightly to the rear, i.e. not perpendicular to the wheelbase. The weight will be shifted to the rear so that the rear shock will sag more and the front less. The rider decides that he doesn't like this and wants the sag in the rear to be the same as when travelling horizontally. So he increases the spring rate to lessen the sag. Now if the same bump is hit at the same velocity in the two different sagged positions, the response of the shock will be greater in the first case with the softer spring. A stiffer spring gives a harsher ride.

Now consider the horizontally accelerating bike. The combination of the gravitational vector and the inertial vector at the CM in response to the acceleration will produce a vector slanting slightly to the rear. Let's make it the same angle as in the previous case. The shock in the rear will sag more than without acceleration if there is less than 100% anti-squat. If 100% anti-squat is added the sag will remain the same. If again the same bump is hit at the same velocity in the different sagged positions, the shock with more sag and less anti-squat will be in effect softer and will have a greater response to the bump.

So much for reason. As for rhyme, here's a poem that might appeal to an engineer.

MEDITATION ON STATISTICAL METHOD

Plato, despair!
We prove by norms 
How numbers bear
Empiric forms.

How random wrong
Will average right,
If time be long
And error slight.

But in our hearts
Hyperbole
Curves and departs
To infinity.

Error is boundless.
Nor hope nor doubt,
Though both be groundless,
Will average out.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> If again the same bump is hit at the same velocity in the different sagged positions, the shock with more sag and less anti-squat will be in effect softer and will have a greater response to the bump.


I was with you until this sentence. I'm not sure how to explain why without repeating what i've already said so maybe you can elaborate on why you believe this situation results in an effective increase of spring rate?


----------



## Steve from JH (Dec 30, 2003)

andy f said:


> I was with you until this sentence. I'm not sure how to explain why without repeating what i've already said so maybe you can elaborate on why you believe this situation results in an effective increase of spring rate?


Let's say you have an air shock. Increasing the pressure has the effect of increasing the rebound or extending force. The anti-squat, which is proportional to the acceleration, is also a rebound or extending force. The one does the job as well as the other.

Consider another variation of the constantly accelerating bike I described before. This time you set it up with 0% anti-squat and increase the shock air pressure so that the sag is the same as if the bike were coasting with the original air pressure. You have the same forces acting on the bike and the same result as with the 100% case, and you clearly have a stiffened spring. It seems to me the burden is on you or anyone else who doubts what I (and the suspension experts I've read) say to prove that the anti-squat does not in effect stiffen the spring.


----------



## andy f (Jan 13, 2004)

Steve from JH said:


> Let's say you have an air shock. Increasing the pressure has the effect of increasing the rebound or extending force. The anti-squat, which is proportional to the acceleration, is also a rebound or extending force. The one does the job as well as the other.
> 
> Consider another variation of the constantly accelerating bike I described before. This time you set it up with 0% anti-squat and increase the shock air pressure so that the sag is the same as if the bike were coasting with the original air pressure. You have the same forces acting on the bike and the same result as with the 100% case, and you clearly have a stiffened spring. It seems to me the burden is on you or anyone else who doubts what I (and the suspension experts I've read) say to prove that the anti-squat does not in effect stiffen the spring.


I was thinking about this after work last night and I finally think I understand what you're saying. I'm convinced you're wrong.

Your examples demonstate a means of creating the same sag as you would have with 100% anti-squat (via an increased spring rate) but they are completely different in terms of any suspension motion which would occur due to an external input.

Also, with no disrespect intended, I would have to read your suspension references myself to believe that you have the experts on your side. I may actually be able to come up with some expert help in this area soon. My 20 year HS reunion is coming up and one of my good friends from those days is a now a lead chassis engineer for Buell. He might have some interesting things to say.


----------



## Steve from JH (Dec 30, 2003)

andy f said:


> I was thinking about this after work last night and I finally think I understand what you're saying. I'm convinced you're wrong.
> 
> Your examples demonstate a means of creating the same sag as you would have with 100% anti-squat (via an increased spring rate) but they are completely different in terms of any suspension motion which would occur due to an external input.
> 
> Also, with no disrespect intended, I would have to read your suspension references myself to believe that you have the experts on your side. I may actually be able to come up with some expert help in this area soon. My 20 year HS reunion is coming up and one of my good friends from those days is a now a lead chassis engineer for Buell. He might have some interesting things to say.


I first read this theory, I believe, about 5 years ago in RACE CAR VEHICLE DYNAMICS by Milliken and Milliken (father and son). It was called the "bible" by the Toyota engineer who e-mailed me years ago. I had a lot of trouble grasping the concept myself at first. I had the same objections you have.

The source I found at random on a search for "anti-squat" that I mentioned above used the term "geometric stiffening" and they were clearly not referring to more than 100% anti-squat but to anti-squat in general.

Your expert friend needs to keep in mind that we're dealing with the equivalent of solid axle rear suspensions on cars, not independent suspensions.


----------



## Steve from JH (Dec 30, 2003)

*More for Andy*

I realized I could quote you from the motorcycle text I have, MOTORCYCLE DESIGN AND TECHNOLOGY by Gaetano Cocco. So here goes, with the accompanying diagram;The angle formed by the straight line passing from the *PofM* [pole of moments] to the point on the ground P and the surface of the ground, is called the *chain pull angle* and will be indicated by the Greek letter [sigma].​ As we can see from the figure, the _force of traction tends to make the suspension extend, thus lifting the rear end of the motorcycle ; the larger the chain pull angle, the bigger the lift!_​ *In practice [sigma]takes on fundamental importance as a design parameter,* because it determines the bike's attitude when driving force is transmitted to the ground. Small variations in the angle can make the same motorbike handle quite differently, since the rear suspension is heavily affected by its influence.​ Let us see in what way: _a large chain pull angle brings on a big change in the suspension behavior depending on whether the rider is accelerating or not._​ A forceful burst of speed rebounds the suspension, so only a very soft, barely preloaded spring is needed to maintain the attitude and pass over holes in the road.​ When the rider closes down the throttle, the rebound effect on the rear suspension disappears, so the rear end tends to squat a lot.​
Notice there is nothing about 100% anti-squat being some magic neutral spot. If the acceleration and the angle are both greater than zero, then some stiffening effect will occur, allowing for a softer spring on a racing motorcycle that is primarily going to be accelerating.


----------

