[zedro]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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).

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]

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

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

 

[andy f]

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]

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]

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]

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.