[rbx]

Analyzing the current suspension types like DW and Maestro, and noticed that the percentage of anti-squat doesnt tapper off after sag point!?

What would be point in keeping a high anti-squat percentage after the sag point when youre no longer pedalling!?

It just leads to more pedal feedback and in my book not necessary or maybe i'm missing something here

 

[dhkid]

i have not looked at them my self, but there might be some errors involved with the linkage programme (assuming you are using linkage)?

secondly, i remember dw saying a while back it was not so much the degree of chain stretch, but the rate of change of chain stretch with travel. there can be still a large amount of chain stretch later in the travel, but it may not be felt by the rider. its only the rapid increase in chain stretch (higher gradients/rate of change) which will be felt as pedal feedback.

edit: another thing to consider is that the dw link was designed with traction in mind, and it just so happens that rearward axle paths improves how the bike pedals/more anti squat and makes it work better on square edge bumps.

you have to remember that suspension design has to cater to many different aspect, braking, bumps, pedaling. the end result is a blend of all the features that make a good suspension design.

ie, the anti squat may not be needed anymore later in the travel, but if you discretely drop the anti squat to zero after the sag point you are going to end up with (approximately) a very forward axle path which will be rubbish for the bigger bumps.

hope this makes sense.

 

[fluider]

Steady antisquat can be useful/desired far beyond SAG. Just imagine Dh race and sprints in every possible straight. Then a pedal clearance may become the only limit.

 

[Steve M]

Also allows for a wider range of sag before you make the bike pedal like crap.

 

[rbx]

Steady antisquat can be useful/desired far beyond SAG. Just imagine Dh race and sprints in every possible straight. Then a pedal clearance may become the only limit.

Depends on how you ride..

I usually keep pedalling in rock gardens but there usually on a straight or slight decline.

When youre starting to hit bigger rocks that are sending you above say the 40% sag limit by then i dont think your thinking about pedalling anymore..

Thats the way i see it but i may be wrong

 

[rbx]

Also allows for a wider range of sag before you make the bike pedal like crap.

But you can still optimise to have the right amount of anti-squat in a range ie 30-40% and then tapper off.

Also by tapering off, you can have a more neutral braking suspension.

 

[Slater]

I lot of it most likely has to do with tradeoffs. Obviously DW doesn't care about anti-squat at full bottomout. But to get it in an acceptable range around the sag point there might be wonky numbers outside that area. This is why you see really high anti-squat numbers from topout to the sagpoint on many DW link bikes. Its just a byproduct of the fact that you have to make compromises with everything.

Also look at the IC migration, and the axle path. the axle path is damn near spot on with a SP of certain location, as the CC doesn't migrate hardly at all (Sunday for example). The Anti-Squat change (or lack thereof) is really just a factor of the migration of the IC. Many of them have significant chain growth because of the axle path, but DW makes some stuff up about the rate of change being the most important. I find it funny because his rate of change in chain growth on the DH bikes using DW links is near identical to all other DH bikes with respectable axle paths.

 

[The Breaker Man]

My boy Slater's wicked smart.....

 

[FlipFantasia]

nerds

 

[rbx]

I lot of it most likely has to do with tradeoffs. Obviously DW doesn't care about anti-squat at full bottomout. But to get it in an acceptable range around the sag point there might be wonky numbers outside that area. This is why you see really high anti-squat numbers from topout to the sagpoint on many DW link bikes. Its just a byproduct of the fact that you have to make compromises with everything.

Well using the linkage program as a reference it seems that DW links does infact care about anti-squat values later in the travel.(looking at the 08 sunday with 36t-15t combo)

 

[monkeyfcuker]

While you're all on the subject would someone mind explaining the differences that a 32-34/38-40 tooth front chainring would make compared to a 36t on my Sunday, I've never actually ran anything but a 36 tooth before.

 

[Slater]

Well using the linkage program as a reference it seems that DW links does infact care about anti-squat values later in the travel.(looking at the 08 sunday with 36t-15t combo)

Just because the anti-squat doesn't dive after the sagpoint doesn't mean he did it intentionally. It could, but it could also mean that it is simply a function/byproduct of all the other aspects of the design that take priority later in travel.

Also if DW does actually design his linkages to have higher anti-squat numbers later in travel, it could be for an unrelated purpose to the performance of the suspension in general. If you design something different/new, you can patent it. All you have to do is make claims as to why this is better than other available options, and you have yourself a patent. Hell, Santa Cruz just did this with patenting any leverage rate that has an inflection point. This is done quite often in different industries, as a way of limiting competition and is also used as a marketing aid.

 

[Steve M]

But you can still optimise to have the right amount of anti-squat in a range ie 30-40% and then tapper off.

Also by tapering off, you can have a more neutral braking suspension.

The DW-link bikes do have ~100% anti-squat between about 25-45% travel, what other usable range do you want? Anti-squat is not related to braking performance, you can literally have two suspension systems with IDENTICAL anti-squat characteristics with completely opposite braking characteristics. Look at any singlepivot with a floating brake for starters.

I lot of it most likely has to do with tradeoffs. Obviously DW doesn't care about anti-squat at full bottomout. But to get it in an acceptable range around the sag point there might be wonky numbers outside that area. This is why you see really high anti-squat numbers from topout to the sagpoint on many DW link bikes. Its just a byproduct of the fact that you have to make compromises with everything.

Also look at the IC migration, and the axle path. the axle path is damn near spot on with a SP of certain location, as the CC doesn't migrate hardly at all (Sunday for example). The Anti-Squat change (or lack thereof) is really just a factor of the migration of the IC. Many of them have significant chain growth because of the axle path, but DW makes some stuff up about the rate of change being the most important. I find it funny because his rate of change in chain growth on the DH bikes using DW links is near identical to all other DH bikes with respectable axle paths.

Think you might want to check your facts there. The Sunday has a reasonable degree of CC migration, forward and upwards within the sag region in order to keep the anti-squat percentages fairly constant. In actual fact it is possible to have IC migration with no change in anti-squat, IC migration WITH change in anti-squat, or no IC migration with change in anti-squat. In other words, IC migration is unrelated to anti-squat change except insofar as to (graphically) determine the CC migration.

As for pedal feedback... any conventional-chainline bike with reasonable values of anti-squat won't have excessive feedback anyway. For what it's worth, the DW-link concept actually works extremely well on this premise; part of the patent specifies that the IC starts forwards of the lower link and "at a later point in the travel the IC is between the two pivots of the lower link", which indicates a deliberate turning point in axle path radius of curvature, in other words, the radius of curvature increases in order to keep the level of anti-squat somewhat constant, up until a certain point at which the radius of curvature actually begins to decrease in order to tighten up the axle path and reduce chain extension. Not many people seem to understand this aspect of the DW-link but in my opinion it is the most brilliant part of the whole system.

 

[Slater]

Oops, I made a boo boo. I've been working with Anti-rise so much lately I transposed IC and CC in my previous post with regards to IC migration affecting anti-squat. This should have stated that CC migration changes anti-squat, and IC migration changes anti-rise.

Although there is enough CC migration on the Sunday to keep anti-squat relatively high throughout travel, it is not enough to affect the overall arc of the axle path that much.

Also, the CC doesn't double back on itself until about 160mm travel on the Sunday, which doesn't matter for Anti-squat since nobody pedals at that level in travel. Also, it doesn't suck in the axle path significantly at all, as a SP which creates a very similar axle path actually sucks in more in the last 40mm of travel.

Regardless, is there a practical reason why you'd want/need 90% anti-squat at bottom out?

I can't think of one.

 

[Steve M]

Oops, I made a boo boo. I've been working with Anti-rise so much lately I transposed IC and CC in my previous post with regards to IC migration affecting anti-squat. This should have stated that CC migration changes anti-squat, and IC migration changes anti-rise.

Although there is enough CC migration on the Sunday to keep anti-squat relatively high throughout travel, it is not enough to affect the overall arc of the axle path that much.

Also, the CC doesn't double back on itself until about 160mm travel on the Sunday, which doesn't matter for Anti-squat since nobody pedals at that level in travel. Also, it doesn't suck in the axle path significantly at all, as a SP which creates a very similar axle path actually sucks in more in the last 40mm of travel.

Regardless, is there a practical reason why you'd want/need 90% anti-squat at bottom out?

I can't think of one.

You're right that anti-squat at bottom out isn't exactly the most critical thing in the world, but the point of reversing the radius of curvature growth is still beneficial even BEFORE the turning point, simply because it means the radius of curvature growth is controlled to the point of at least approaching zero. Nobody is pedalling at an AVERAGE displacement of 160mm into the travel, but that's not to say the suspension never reaches that point while you're pedalling - one decent size rut will easily reach that. It doesn't mean there's no other way to make a bike pedal well. As you said before, having relatively high anti-squat values at bottom out is almost certainly a by-product of achieving other characteristics. If I was designing a bike (assuming I wasn't limited by patents or whatever), the anti-squat profile would not be identical to the Sunday, but it'd have some similarities for sure. A SP bike which maintained similar anti-squat values through the typical sag range would have a pivot that was relatively high and far forwards compared to the CC of the Sunday, and would actually have significantly worse chain extension and higher anti-squat than a Sunday towards the end of the travel. There is no getting around this - the CC of the Sunday is within the rear wheel for a significant portion of the travel.

Another advantage of near-constant anti-squat over a wider range of travel is that different gradients (up vs flat vs down for example) load the rear wheel differently. Climbing will always weight the rear wheel significantly more than descending for obvious reasons, meaning the sag will be greater than when descending. Even flat ground vs descents register noticeable differences. Obviously the variation in gradients that you can actually pedal on don't vary as significantly on a DH bike as on say an XC race bike, but regardless, if you CAN do it you might as well.

 

[slowmtb]

No U R

 

[dw]

Analyzing the current suspension types like DW and Maestro, and noticed that the percentage of anti-squat doesnt tapper off after sag point!?

What would be point in keeping a high anti-squat percentage after the sag point when youre no longer pedalling!?

It just leads to more pedal feedback and in my book not necessary or maybe i'm missing something here

I've sporadically read a few points here, and without getting overly complex I have a couple points to make.

1) All of you should read what Steve (Socket) is writing carefully. In my estimation, he's got the best handle on what's going on here of anyone participating in this thread to this point, and he's trying to help.

2) I've done a huge amount of instrumentation and data acquisition, which illustrates unequivocally that just about every rider tested pedals after the sag point, which is typically between 20-40% of travel. Most riders are still pedaling significantly up to 60-70%, and few after 80%.

3) If you are using the "linkage program" to "analyze" suspensions, remind yourself that the data that you are getting is in large part inaccurate, incomplete, and in most cases worthless.

4) The dw-link bikes have significant IC and CC migration, The Maestro bikes do not have significant CC migration. If that type of thing is important to you.

5) The Sunday and all of the other IH bikes are ancient history AFIAC. I designed them between 2002 and early 2004. Take a look at more current dw-link.

6) Some of the anti squat amounts quoted in this thread are so off base it's comical. 90% anti-squat at bottom out??? Not on any dw-link bike.. Refer back to point #3.

7) The dw-link anti-squat profile is 100% tactical. There is no chance to it. I am mathematically characterizing every aspect of the bike's performance and specifically tuning different traits to meet my goals and the goals of my partners.

8) I am stoked that someone (Steve) has picked up on and understood the subtle points of the dw-link axle path and what I'm doing with it to keep pedal feedback managed late travel. Pretty cool, huh? I always thought so, but then again it's my baby.

I don't have much else to contribute here that I haven't typed 600 times before.

 

[I.van]

The dw-link anti-squat profile is 100% tactical.

If that phrase doesn't become a marketing slogan I am going to be severely dissapointed.

 

[dw]

If that phrase doesn't become a marketing slogan I am going to be severely dissapointed.

haha

unfortunately I've always been a lot better at making actual products than spending my personal time on marketing.. I should probably try to change that, but I probably wont.

 

[MarkDH]

The Sunday and all of the other IH bikes are ancient history AFIAC.

You just made my Sunday cry, like a faithful dog being kicked in the ribs by its master.

 

[dw]

You just made my Sunday cry, like a faithful dog being kicked in the ribs by its master.

Don't get me wrong, they are still super rad and in my opinion lightyears ahead of the vast majority of Brand X 2010 and 2011 models that are being thrown out there as "the latest and greatest" but I've refined my craft over the years and my latest and greatest work is always an attempt to improve over my best work of the past.

 

[Udi]

Yeah, 2x world championship winning ancient history.

 

[freeridefool]

I've sporadically read a few points here, and without getting overly complex I have a couple points to make.

1) All of you should read what Steve (Socket) is writing carefully. In my estimation, he's got the best handle on what's going on here of anyone participating in this thread to this point, and he's trying to help.

2) I've done a huge amount of instrumentation and data acquisition, which illustrates unequivocally that just about every rider tested pedals after the sag point, which is typically between 20-40% of travel. Most riders are still pedaling significantly up to 60-70%, and few after 80%.

3) If you are using the "linkage program" to "analyze" suspensions, remind yourself that the data that you are getting is in large part inaccurate, incomplete, and in most cases worthless.

4) The dw-link bikes have significant IC and CC migration, The Maestro bikes do not have significant CC migration. If that type of thing is important to you.

5) The Sunday and all of the other IH bikes are ancient history AFIAC. I designed them between 2002 and early 2004. Take a look at more current dw-link.

6) Some of the anti squat amounts quoted in this thread are so off base it's comical. 90% anti-squat at bottom out??? Not on any dw-link bike.. Refer back to point #3.

7) The dw-link anti-squat profile is 100% tactical. There is no chance to it. I am mathematically characterizing every aspect of the bike's performance and specifically tuning different traits to meet my goals and the goals of my partners.

8) I am stoked that someone (Steve) has picked up on and understood the subtle points of the dw-link axle path and what I'm doing with it to keep pedal feedback managed late travel. Pretty cool, huh? I always thought so, but then again it's my baby.

I don't have much else to contribute here that I haven't typed 600 times before.

God what does that dw guy even know... Its like he thinks the designs these bikes.

 

[time-bomb]

Its like he thinks the designs these bikes.

 

[IH8Rice]

 

[Sandwich]

 

[time-bomb]

God what does that dw guy even know... Its like he thinks HE designs these bikes.

fixed, now it makes sense. just finished my coffee, i should be able to read between the lines better going forward.

 

[Slater]

Haha and down she goes!

Linkage is useless? Hardly. The physics and functions that determine all but the anti-squat and anti-rise are all elementary. And even so, linkage uses your (DW's) definition of anti-squat. Perhaps it leaves out a few other smaller forces that also contribute, but the major stuff is there. Not to mention the calculation of anti-squat for motorcycles has been well defined for over 25 years, and is virtually identical to that used by linkage.

Saying in essence that you don't have to make any compromises in designing a suspension system is hilarious as well.

Also, if CC migration is so significant on DW bikes, why are the resulting axle paths so similar to a constant arc axle path? We're talking well within single digit percentage differences here.

I know that there are tons of DW fanboys here and this will fall mostly on deaf ears, but I hope one day we can cut through all the BS and marketing that apparently isn't marketing and get to a real conversation about the kinematics themselves.

 

[imp]

+1 on motorcycle suspension, my introduction to the whole thing was Tony Foale's book.

It seems a little defensive to bash 'linkage,' it's a just a set of tools from classical mechanics, how inaccurate can it be?

I get there there is much to learn about rider habit from acquiring data on the trail, but the fixed points in space don't change from a model to the real world, and neither would a behavior like anti squat... the pedal goes down, the chain ring spins forward, etc. What's the mystery dynamic?

Not trying to be adversarial-- exactly the opposite. Just curious.

 

[rbx]

Point 2) is exactly what i was trying to discuss about, very interesting what you found about pedalling beyond sag point, now the DW-link seems to be more logical.

Point 3)For finding anti-squat diagram the linkage program is pretty spot-on
(I verified the numbers in my CAD program)

Thanks for replying

 

[Steve M]

Haha and down she goes!

Linkage is useless? Hardly. The physics and functions that determine all but the anti-squat and anti-rise are all elementary. And even so, linkage uses your (DW's) definition of anti-squat. Perhaps it leaves out a few other smaller forces that also contribute, but the major stuff is there. Not to mention the calculation of anti-squat for motorcycles has been well defined for over 25 years, and is virtually identical to that used by linkage.

Saying in essence that you don't have to make any compromises in designing a suspension system is hilarious as well.

Also, if CC migration is so significant on DW bikes, why are the resulting axle paths so similar to a constant arc axle path? We're talking well within single digit percentage differences here.

I know that there are tons of DW fanboys here and this will fall mostly on deaf ears, but I hope one day we can cut through all the BS and marketing that apparently isn't marketing and get to a real conversation about the kinematics themselves.

I agree about Linkage - it is just a calculator. If you put bad data in (like clicking on ****ty pics from side-on as your inputs, which I think is one of DW's pet hates because for bikes with such short links you need to be REALLY accurate) then you'll get bad info out. The newest version of Linkage includes a proper anti-squat calculator based on the generally accepted means of calculating anti-squat on chain-driven vehicles. You can use ADAMS and still get useless outputs if your inputs were never accurate. If you're actually measuring stuff up properly then Linkage is as useful as anything else; if you're actually developing the linkage from scratch then it's even better because it's exact. It lacks information on the damper side of things though, but at least it does allow you to export rate curves to use in conjunction with known damper curves to generate proper wheel rates.

How are you defining "single digit percentage differences" between axle path? Sounds kind of like saying red is 41% different to blue... at any rate, if you ARE using Linkage then it is possible that your pivot locations aren't 100% correct - there is an excellent side-on schematic of a Sunday from 2005 floating round that you can blow up and use to get the pivot points within fractions of a mm of exact. The axle path doesn't do anything visually crazy, that's what subtle tuning does, but the CC does visibly move forwards and slightly upwards, then backwards from memory. Varying the axle path a couple of degrees at a given point in travel changes the anti-squat percentage distinctly, yet visually you'd say it's "almost the same". If you want to see some crazy W-shaped axle path or something then maybe you need to look at some wackier and lower performing bikes

 

[Slater]

How are you defining "single digit percentage differences" between axle path? Sounds kind of like saying red is 41% different to blue

I've dicked around in linkage and created a suspension with an SP location that creates an axle path that deviates no more than 10% from the axle path of a Sunday (with my own image). I've done the same for a V10 but, but have to limit travel to 8" or so, otherwise it deviates more than 10% at the end of travel.

Anyways, the point is that CC migration in pretty much any of the popular multi link designs to date like DW or VPP affects Anti-Squat a lot more than Axle path.

 

[ska todd]

at any rate, if you ARE using Linkage then it is possible that your pivot locations aren't 100% correct - there is an excellent side-on schematic of a Sunday from 2005 floating round that you can blow up and use to get the pivot points within fractions of a mm of exact.

IIRC any side shots we published 05-08 on dw-link bikes were at the very least slightly distorted, angled, squished, or otherwise manipulated so that competitors couldn't exactly copy something the lazy way. It would look pretty close but would be slightly off. That's one of the reasons people would complain that our HTA or BB height wasn't what was published...and a couple of those key numbers were slightly manipulated for the same exact reasons. They'd have to go and physically buy one. I know that happened at least on two occasions with Supergo stores in California.

-ska todd

 

[Vrock]

Every time that we speak about the linkage program, DW comes and bash the program... he never miss a thread. But he has NEVER posted an Antisquat curve of any DW bike. If he post one, we could compare the real thing with the Linkage one and see how off we are. 10%? 20%? 30%?

Going back to topic... A lot of people pedal beyond the sag point, lets say until 60% of travel. So dropping the level of Antiscuat so early is not ideal. If you drop the curve you'll have less feedback but you have to use the bike with the recommended SAG or you'll loose some performance. Each option has pros and Cons.

To me, Feedback is not so important so I have a good opinion about DW-Link Bikes. The only problem now is that with the new generation of shocks, RC4, Elka... They are probably too Progressive.

 

[fluider]

I'm definitely for level anti-squat far beyond SAG point. And I'm surely against any damp. platform contained in the shock to prevent susp. movement from acceleration. As far as I remember this idea was firstly and greatly propagated by DW and also he shows that it's a good way to follow.

Any of them, bike designers, can bash at Linkage as much and long as they want. Till they don't show at least some outputs from their ultimate all-physics calculation-simulation-validation software I'd told them to be more quite. The Linkage is the only tool available there for such a pretty cheap money that can handle some basic linkage properties. Which manufacturer had used to publish information available in Linkage before Linkage was available? We would be surprised how many well-respected designers use Linkage. The physics essays written around this program and PUBLICLY available FOR FREE (no-one else has done it yet) might be more valuable than Linkage itself.

 

[Steve M]

IIRC any side shots we published 05-08 on dw-link bikes were at the very least slightly distorted, angled, squished, or otherwise manipulated so that competitors couldn't exactly copy something the lazy way. It would look pretty close but would be slightly off. That's one of the reasons people would complain that our HTA or BB height wasn't what was published...and a couple of those key numbers were slightly manipulated for the same exact reasons. They'd have to go and physically buy one. I know that happened at least on two occasions with Supergo stores in California.

-ska todd

Yup, and I know those Hollowpoint Illustrator files were deliberately manipulated to misrepresent the linkage of the actual bike... but I own a Sunday and a tape measure as well as a few schematic pics

disclaimer: I am fairly drunk right now.

 

[miuan]

It's funny to imagine that manipulating pics can prevent anyone from copying design of a bike that can be purchased and copied afterwards. If I was to copy a Sunday, I would buy several of those frames from different batches to minimize error.

 

[Steve M]

It's funny to imagine that manipulating pics can prevent anyone from copying design of a bike that can be purchased and copied afterwards. If I was to copy a Sunday, I would buy several of those frames from different batches to minimize error.

Yes but this is the bike industry, it's run by professional amateurs.

 

[dilzy]

Dave, post an anti-squat vs travel graph for one of your DW link bikes, because the ones I've had a play on bobbed like nothing else.

Not really fussed on you bashing linkage, it's a mathematically perfect tool as far as linkage curves go. It's also much quicker than anything else I know. I have full multiphysics version of Ansys 12.1 and am more proficient at it than anyone I know, but it's still bloody slow.

Also about compromise, as some other bloke said, pull you head out of your arse you don't compromise.

 

[Honus]

Yes but this is the bike industry, it's run by professional amateurs.

And truer words were never spoken....

Any time I hear the term "no compromise" I have a good laugh. Any design engineer worth their education and work experience knows that good design is all about compromise. The good designers simply compromise the least in achieving their design goals- and in that regard the DW Link is very, very good.

I think the original question has been answered at this point. I think that's why we've seen more and more long travel bikes with short bar four link system in the last several years (at least it appears that way to me)- it allows the designer to better manipulate axle path and anti-squat values, but you can still only go so far in terms of rearward axle path without using an idler or gearbox due to chain extension -which leads to drive train inefficiency. So these bikes tend to start out with a rearward axle path for the first half of the suspension compression and then go more vertical/inward to manage chain extension.

What is the big deal about DW posting an anti-squat plot? If you don't like the way it rides then use your knowledge to build your own frame that fits your riding style and move on.