Nerding Out: Do Kinematic Graphs Really Describe Suspension Performance?

Aug 4, 2022 at 8:08
by Seb Stott  

Recently I spotted this intriguing comment in Alicia Leggett's Revel Rail review.

bigquotesThe techniques that have been developed to measure how active the suspension is on a bicycle - anti-squat and anti-rise - appear to be fairly unremarkable when it comes to this design. If they don't tell the full story, what measurements do we have that do? How do two bikes with the same leverage curve have different suspension forces, all other things being equal?

The Rail's anti-squat and leverage curves don't look very different to many other modern bikes, so does that mean the suspension won't perform any differently?

This topic is something I've been thinking about a lot ever since I reviewed the Marin Wolf Ridge 9 back in 2018. That bike is one of three I've since tested using Naild's R3act suspension system, which features a sliding suspension component in combination with links. The marketing claims implied that it worked in a fundamentally different way to other designs, allowing it to take all the best characteristics of other systems with none of the downsides. Information on how it did this was nonexistent (and I did ask, a lot), but I was told not to worry about the kinematic graphs because Naild's system worked in a different way to other bikes, so its true brilliance couldn't be explained using the usual methods.

By the way, if you're wondering what terms like "anti-squat" and "leverage curve" even mean, I recommend Dan Roberts' articles on the topic here and here.

Pinkbike-Polygon-3-2017
The Naild suspension system looked different and was tuned in an interesting way, but its behaviour could be explained by the usual suspension analysis tools.

In reality, the Naild system operated in the same plane of physical constraints as any other suspension system. It's essentially a four-bar suspension layout, except it uses a slider in place of one of the link pivots, so the usual tools (anti-squat, anti-rise, leverage ratio, etc...) explain how it operates about as well as any other bike. As you can see in this article, it was tuned toward high anti-squat and high pedal-kickback compared to most other bikes, and that's no bad thing as it made it pedal very efficiently despite a lightly-damped shock, but there were drawbacks to this.

So, I would be very skeptical of any brand telling you that their layout - no matter how many links, sliders or flippy-spinny bits it has - is so revolutionary that has benefits that can't be seen on any kinematic graphs, or that they manage to side-step the usual compromises. Suspension is all about compromises.

Can you describe what the bike's doing here with a graph?

But to answer the core of the question, do these graphs tell the whole story of how the suspension works? Absolutely not.

Firstly, there's a lot more to unpack in these wiggly lines than is sometimes made out. People often quote a single number - such as the percentage anti-squat at sag, or the change in leverage ratio between the start and end of the travel - as if it tells the whole story, but there's a lot more to it than that. For example, the gradient of the anti-squat curve may affect how firm the suspension feels under power, or the shape of the leverage curve as it wiggles between the start and end points may be more important than the leverage numbers at those two points.

Another caveat that's often forgotten is that anti-squat and anti-rise depend on the center of gravity position of the bike and rider, so if you're comparing anti-squat curves between two different bikes, they aren't directly comparable unless both are calculated with the same set of assumptions for the COG position. The frame size, chainring and sprocket selection also have to be the same to make things fair. But with all of those caveats and subtleties out the way, the kinematic graphs do describe the suspension linkage very well.

But how the suspension behaves and how the bike actually rides depends on much more than the frame linkage. The choice of shock and its damping tune are arguably more important still - in the case of that Marin Wolf Ridge, the light damping tune is probably the main reason the suspension performance was so unusual and opinion-dividing, not the slider. Meanwhile, the geometry, wheel size and componentry can also affect how much harshness is transmitted to the rider. All these factors and more interact with one another in a way that's too complicated to put into any graph. That, I hope, means we bike reviewers will still have a job for the foreseeable future.





157 Comments

  • 219 10
 I'm willing to bet most of us don't care about suspension kinematics. Why don't we nerd out on shitty warranties instead.
  • 6 0
 Excellent point !!
  • 59 1
 If gladly ride with the current kinematics that aren’t optimal in exchange for an X2 that didn’t shit the bed so often.
  • 32 17
 Suspension kinematics + suspension damping curve + suspension spring curve = 90% how the bike rides, so you do not care how your bike rides, ok. The primary function of the bike is riding, why would I ride shitty bike because the company handles warranty well?
  • 9 0
 @vw4ever: Same here with the DHX2, 4 times on warranty repair and it is already starting to go again after 3rd ride.. That is some major fox diarrhea.. Frown
  • 19 1
 so the orange single pivot was right all along then
  • 10 1
 @lkubica: I think that if those three things add up to 90% and most bikes are pretty similar(bikes have gotten really really good lately), We're looking at some 88%, 86%, 89%, maybe even 90% for the perfect bike. The other 10% really matters. If the 86% bike handles warranty better than the 90% bike, maybe I would pick it instead.
  • 11 2
 I think most people do care about kinematics. They just don't put the effort into understanding them. If the next bike you bought rode like a Klein Mantra you would suddenly realise kinematics are very important indeed.
  • 1 0
 @i-am-lp: what happens to them? mine (6 month old bike) is fine so far.
  • 1 0
 @vw4ever: please elaborate. I just got rail29 with x2. Lets hope i dont have issues
  • 7 1
 @Rukman: Very early cavitation- it was warrantied, but not long after the 6 month warranty (of the warranty service) it did it again. Also stanction wear through the anodization. I take care of my bike and through the pandemic, I was able to ride less often, maybe once a week on average due to extended or extra isolation shifts. But apparently it was all my fault for "lack of maintainance".

It's a lovely shock and feels great when it's working, but based on others i've talked to and my own experience, the longevity just isn't there. If you keep it, I'd recommend sending it in for service well before you calculate that it is due, because it's unlikely it will make it to the service interval (I believe it's 125 hours) before it has issues. Which is a real bummer for a shock that is this expensive.
  • 2 1
 @gabriel-mission9: I agree. If a reviewer showed me a leverage curve graph instead of telling me how the bikes feels, I certainly wouldnt make the effort to try to figure it out on my own. i'd rather just ride the bike myself. tell me how well it does in the environment its suited for, not how well it looks on paper.
  • 4 0
 Thankfully, when you get older, you don't ride a bike rough enough anymore to worry about warranty. Wait, maybe I never had enough balls to push a bike to warranty abuse levels. Who knows.
  • 2 0
 @lkubica: because we’re not good enough at differential equations to optimize that multi-variate function, especially once we introduce rider, weather, trail conditions, etc. fixed effects.
  • 2 0
 @vw4ever: What trouble has your X2 given you? Been running one 3 years or so on an SB150 and either it's fine or I'm too dumb to notice something's wrong...
  • 4 1
 @davidrobinsonphoto: cavitation is the diagnosis from Fox themselves.
  • 1 0
 @impossiblivion: yours might be an earlier generation- but I suspect the stanchion wear may be due to the orientation of it on the frame with the air can on the bottom. I could see how the oil could sink to the bottom and leave the seals dry, but that’s just a guess.

But the thing that tipped me off was the sloshing sounds and the lack of damping.
  • 5 0
 @vw4ever: fox is absolutely trash in recent years.. i’ve heard so many stories of blown shocks that i dont get how it is still not a major scandal.. pretty much everyone i know who rides fox had to do a service because of some major fault at some point..
  • 4 0
 @i-am-lp: Should have gone EXT....
  • 5 0
 @vw4ever: seal head oring or shaft seal failure leads to aeration. Aeration is different from cavitation.
When I rebuild them I set the ifp at minimum depth and raise the ifp pressure by 25psi.

Gives a better chance against the huge pressire the air chamber at bottom out
  • 3 1
 @REZEN: agreed. There are numerous more reliable options out there. Fox isn’t worth what you pay for it (though someone has to pay for all those sponsorships and brainwashing-I-mean-marketing ads). I would much rather be riding Manitou. For durability, get a coil and be done with it (EXT and esp. Avalanche bespoke are both incredibly durable).
  • 2 0
 @vw4ever: Are you talking about the problem where you get nitrogen blowing thru some of the seals and winding up in the damper oil? They really crappy squelchy feeling? That is an obvious problem when it happens, makes the shock unusable.
  • 2 1
 @st-lupo: it's not nitrogen it's air from the air spring, entering at the damper seal, or the oring on the OD of the sealhead.
  • 2 1
 @st-lupo: sounds like what you are describing- the tech referred to it as cavitation but perhaps he didn’t have his own jargon correct.

Thanks for all the people setting me straight!
  • 1 0
 @vw4ever: do you keep having a repeat problem with it?
  • 1 0
 @englertracing: good thing that seal from fox is only $1 new
  • 1 2
 @davidrobinsonphoto: as a former suspension tech, yes you are right, but it's common place to use the term cavitation instead as that's already commonly used (wrongly) by Joe Public, so it's easier to just explain the issue then having to explain both the issue and the terminology. Especially when the point is their service is no longer just a service and x£'s more than expected.

Also this should be a major thing about fox, they have made several design changes over the life of the x2/dhx2 life cycle that's actually made them less reliable. (Although the 2019 air can update did help) they are genuinely bad shocks atm, and poor knock off of what ccdb could do (excluding air versions)
  • 1 0
 Suspension kinematic explained m.youtube.com/watch?v=hlv672jqbtE
  • 1 0
 @CFR94: yep, second time around with same problem (air mixing with damper oil) at about 8 months of use and no where near the service interval hours-wise.
  • 1 0
 @st-lupo: exactly.
  • 1 0
 @vw4ever: just buy a Cane Creek Kitsuma.
  • 2 0
 @An-Undocumented-Worker: that's the design That ohlins licensed to cc look up an ohlins ttx25 it's a road race shock. Poppet degressive. Ohlins only uses that layout on road racing apps...... and licensed it to someone else for dirt. The layout ohlins uses for dirt is totally shim based....the ttx22 is a superior format
  • 73 5
 Math is fun, but Bikes are More Fun…. My Spire has a graph that just spells out “Party in the Woods!”
  • 11 0
 The only graph I understand
  • 28 21
 Nah, your Spire graph reads "pretty good, but much better with a cascade link and coil shock"
  • 1 0
 AAAAmen!!!
  • 6 2
 @bikebasher: judging by the number of links that CC makes, that would likely be the case for many bikes.

@cascadecomponents why don’t you just design or consult for the rear suspension kinematics of brands? You could retire early.
  • 2 0
 @vw4ever: maybe they are, think some dh and ebikes with their design help should hit the market soon
  • 39 0
 @mtb-jon: My Hardtail's graph is easy to understand.
  • 15 0
 @vw4ever: I think cascade would be the first to tell you their links are not for everyone. Many of the frame applications they make links for raise the leverage ratio pretty substantially so would not be recommended for heavier riders. Also not everyone needs/wants a ton of additional progression. I would say in general they are designed for a more aggressive riding style. however, they recently released a long shock kit for the Turbo Levo that replaces a 210x55 with a 230x65 so that it makes the leverage ratio more favorable for heavier riders. So probably wouldn't recommend that kit if you are on the lighter side.
  • 3 1
 @bikebasher: my Norco optic graph also showed it would ride better with one of those links.
  • 2 0
 @vw4ever: can confirm their links have made my sb130lr and stumpy evo feel better for my terrain and riding style
  • 2 0
 @bikebasher: nailed it. My CC linked Spire agrees.
  • 1 0
 @bikebasher: can confirm
  • 1 2
 @notsosikmik: oh yeah, not saying that they can make one for every frame- just saying that they clearly have an idea how suspension should work, and could help bike brands (like my Norco Sight) that are less than optimal right out of the gate.
  • 1 0
 @avg-roadie: now we’re talking.
  • 9 0
 @notsosikmik: most of us mtber’s are nerds for upgrades of any kind. Sometimes too much so. I think alot of people simple just see those sexy machined & ano’d Cascade Links and simply put them on their bike for the trailside bling factor. Forgetting the fact that it is a niche product that alters their suspension, possibly even in a negative way for their prefered riding style and suspension set up.
  • 4 3
 @brycepiwek: Disagree with that in most cases, just because the Cascade links are pretty ugly compared to the smoothed over stock links/rockers that come with the Transition and Specialized frames. I think those buyers are getting them for the performance rather than the looks. Not sure about the others.
  • 1 0
 @ghill28: i agree with that. no one could tell that my bikes have different links unless they were looking for that change specifically
  • 1 0
 @ghill28: oh I agree on the looks part, I can’t say I like the looks of them either. But then again that’s subjective.
  • 14 0
 @vw4ever: You're not looking at the big picture. Norco and other brands don't design bikes for Pinkbike members and hardcore riders that like to hit the gnarliest trails as fast as possible. They design them for their general sales market which includes all kinds of people, some of which will never leave the nearly paved rail-to-trails. So they design their suspension to a more middle-ground point which will accommodate all their buyers better. CC probably makes great stuff that works very well for intense experienced riders, but that's hardly the majority of people buying bikes. So no, bike companies don't want help from CC because they are targeting different markets. It's the same reason Toyota doesn't just build Supras, because most people want a much more lame but more practical Camry.
  • 6 0
 @robw515: pretty awesome we live in world where bike manufacturers make stuff we like and then other companies can help us to refine the performance of those bikes even more!
  • 6 0
 @robw515: You get it!
This crazy son of a bitch gets it!

@brianpark, @mikelevy, @mikekazimer get this guy a huge prize of some sort, frig yeah!

Is there a way to make this comment appear at the top of every bike and suspension review?
Make it bold, and flash and other cool shit

Along with a comment on the uselessness of suspension clicks for pros in bike checks (other than pure curiosity)
That there is no “right” suspension fork, or brake, or wheel size, flat or clipped, just a personal preference.
  • 5 0
 @brycepiwek: I don’t know if it’s for the “bling” factor — though I’m sure that’s part of it — but I see so many people say they are going to “upgrade” to a Cascade link. I always wonder if they know it’s not necessarily going to be an upgrade, but it’s going to be different… and you might not like it.
  • 2 0
 @notsosikmik: I wish Cascade would make more links that keep the original curve, just lower the entire ratio.
  • 1 0
 @ghill28: as a fan of soviet brutalism,, I love the look
  • 1 0
 @robw515: I think you’re giving PB riders too much credit.
  • 1 0
 @robw515: yeah but Toyota doesn't even build their own supra anymore, BMW does
  • 2 0
 @greenblur: out of curiosity, why’s that?
  • 1 0
 @vw4ever: Oh hey specialized, you need me do design your suspension so I can retire, ok? Thanks in advance!
  • 1 0
 @vw4ever: you overestimate the wages in the industry
  • 2 0
 @spaced: this right here. All the engineers that got A's and B's in school work in Aerospace or other lucrative fields.

And the carbon they use for bikes is fairly low end compared to aerospace/defense/motorsports.

So just remember when you're bombing down some steep shit, your bike was designed by an underpaid C minus student using low end materials.
  • 1 0
 @greenblur: As someone who has worked in the bike industry for 20+ years I will disagree. I know quite a few smart folks who came from aerospace/high tech to bikes because ....they love bikes. It's not all about the money for everyone.

And as for materials and techniques, when Speshy partnered with the McLaren F1 carbon guys for some frame designs, you can bet they didn't use the cheap crap.

Bikes are like anything else, they range from Ferrari to Ford in terms of quality. I've got an F-150, I know low quality! :0
  • 1 0
 @bikebasher: 20+ years and you use Ferrari and Ford as your examples? You been in the marketing devision for that 20 years? Lol
  • 1 0
 @TheBearDen: curious, what are your concerns with @bikebasher examples in this situation?
  • 44 0
 I feel betrayed. I was looking forward to nerding out on maths and physics, turns out we didn't nerd out at all. Gimme formulas I don't understand man!
  • 13 3
 e^(i*pi)-1=0
  • 2 0
 @tbmaddux: upside down that reads 'boobs' smh, you're not a maths professor at all are you Mr Maddux eh.
  • 1 0
 @tbmaddux: Euuuuugh
  • 1 0
 @tbmaddux: i better be 0 then.
  • 6 0
 @tbmaddux: realized you didn't mean some i, but the i! But then e^(i*pi)-1=-2 would be true eh?
  • 3 0
 @sorrymissjackson: it's not, you gotta go to imaginationland

en.wikipedia.org/wiki/Euler%27s_identity
  • 9 0
 @bkm303: According to that article, the signs are flipped. It's e^(i*pi) + 1= 0

So e^(i*pi) = -1 and then e^(i*pi) - 1 = -2
  • 2 0
 1+2+3+4+... = -1/12 (go home maths, you are drunk)
  • 4 0
 @pmhobson: finally the nerding out is ON!
  • 1 0
 @pmhobson: The correct answer.
  • 4 0
 @Alex-E: Glad I can still rearrange equations. Still though, mad props to @tbmaddux for bringing Euler to pinkbike in any form.
  • 1 0
 @pmhobson: the most beautiful equation in mathematics, my professor used to say
  • 2 0
 @Nobbinam: it is…suspiciously elegant
  • 3 0
 @pmhobson: I actually prefer Lagrangian mechanics for riding.
  • 2 0
 @tbmaddux: a man after my heart, I see!

(We should have an Oregon Water Nerds ride at some point. There are dozens of us!)
  • 7 0
 @tbmaddux: you can obvisly rewrite it as:
E^(p*i*i)+1=0
E^p*i^2+1=0

Also the formula for the volume of pizza with radius z and heigh a is pizza.

Quick mafs for yall
  • 3 0
 where laser cats?
  • 36 1
 If you insist on nerding out, how about a blind test... don't give the tester any data, have them ride the bike, and graph out what they perceive. Also time controlled sections. Otherwise, I feel like much of this is just confirmation bias.
  • 2 0
 This!
  • 7 3
 Totally agree. And when it all comes down to it you can collect data to prove anything you want to sell. Like the whole recent "short cranks are better" bs. My short cranks ARE better at clearing rocks but my ride times are consistently faster with longer cranks. For suspension, the hype has been on progression but there are some really awesome/fast bikes that have more linear curves. I really wish journalist would stop trying to be engineers.
  • 2 0
 @foggnm: this. Theres no universal better. The use case matters.
  • 5 0
 Two middle aged men were arguing about suspension. A 10 year old came through and sends a back flip.
  • 2 0
 It's actually really hard to ride a bike with a blindfold on, i think that's the main reason they don't do this.
  • 1 0
 @foggnm: thanks man! I felt so alone, I thought I was the only one liking longer cranks for pedaling!
  • 20 0
 I scrolled down to read more but the article was finished.
  • 4 0
 Lol - yeah me too. Feels like we only got the first half.
  • 6 1
 didn't even address the revel that started the whole conversation. seems like it would have been a good place to get input from some of the kings of suspension design... get weagle, canfield, etc all talking kinematics and you would be onto something.
  • 14 0
 First, glad to hear about the effect of the anti squat curve gradient, Seb !
I'm with you physics laws are very hard to break haha.
Kinematics are physics based and 100% accurate, but I argue we can look are better metrics.

Conventional leverage ratio curves describe perfectly the mechanical advantage of a vertical input at the contact patch on the shock. They are 100% correct but how relevant are they to riding?

What about the contribution of the shock? why is it always discussed in a subjective way?
looking at the combined leverage AND shock rate (which varies a lot) could tell us so much more!

Also, MTB ride on bumps, why are we only checking vertical leverage ratio?
The added suppleness of a high pivot doesn't show on a leverage curve. You can look separately at the axle path but how to synthetize this in your head? impossible.
Why not use vertical leverage AND leverage for different bump heights? Just like we look at anti squat for different gears.


If you are interested, here:s how I advocated for better metrics a couple years back: www.datumcycles.com/tech/#iFrame3
  • 4 4
 If suspensions companies started to show they damping curves to the public and public was quickly educated about what damping curves means, the suspension companies would very quickly have a hard time selling their shitty digressive damping curves, inspire by road racing and loved by the crowd of people that believe you shouldn't use a climb switch. That would also mean that bike companies could stop trying to compensate shitty suspensions by using massively falling rate ratio curves. While we are at it we could also stop having fork dampers aimed at the gravity side of things being screwed just to have a platform or lock-out setting.
  • 2 0
 What you are asking for is not MORE information, but LESS information. You cant combine a system with so many degrees of freedom into a single 2D graph and have it be informative. Thats why we have 5 graphs.

As to specific questions regarding shock contribution or high pivot suppleness, these are also dependent on shock speed not only position, so how to plot them?
  • 2 0
 A graph that represents axle path and leverage rate is definitely possible. I think the simplest solution would just be to draw the axle path and then use the colour of the line to represent the leverage rate at that point. Not the kind of thing a sales rep is gonna pull out on the shop floor to make a sale, but i think it would be fairly comprehensible for anyone interested enough to be looking at graphs like that in the first place.
  • 13 2
 What really makes me scrambled head is when folks rely on reviews to make buying decisions.

Consider the following:

Is the reviewer like you?
Is the reviewer biased?
Do you have enough to experience to know good from bad?

Many folks ride bikes that are so poorly set up that it wouldn’t matter what bike they were riding.

A good bike with a poor set up will ride poorly.

One of the most telling things is to see how poorly demo bikes are set up, the first thing I do when I get a demo … once I’m out of sight of the tent, I pull out the multi tool and the shock pump, fifteen minutes of tweaking until it feels adequate, then I go ride for at least an hour, on terrain I know, and I continue to tweak throughout the ride.
  • 1 0
 Valid point about the personal preferences of the reviewers. I've seen reviews of high pivot bikes where some people(Paul Aston) say they feel totally planted in the corners, while other reviewers say they feel odd in corners because the rearward axle path. It could be different setups, but it could also be because a reviewer is more used to riding low pivot bikes, or they are more suited to their riding style.

So many variables, which the article does a good job of analyzing. Don't necessarily trust the marketing, don't trust the linkage graphs alone, but also realize the reviews have a certain amount of subjectivity in them.
  • 9 0
 Kinematics are important and can be useful info, but they certainly don't tell the whole story. Lateral stiffness of a frame or lack of can change the ride characteristics a lot between two bikes with identical kinematics and shock tune.
  • 9 0
 I think most of us have swapped shocks on the same frame and experienced how much of an impact that can have on all aspects of the ride, so the graphs are useful, but certainly not the whole picture.
  • 1 0
 Indeed. Installing the Corset air sleeve on my Bronson was a big change for the better.
  • 13 1
 Pick a curve and be a dick about it.
  • 4 1
 peyronie's disease Definition?
  • 3 1
 A little to the left
  • 3 2
 pick a dick something something curve about it
  • 2 0
 Pick a dick with a curve on it
  • 14 3
 I have no idea what I just read....
  • 9 1
 Nearly every bike is so good these days I can't think of one I wouldn't want to own for a year or two. I don't care about the curves, just hoik the OEM tyres and maybe swap brakes and I'm done. And yeah, buy it from my LBS.
  • 10 0
 Are the graphs important .? No the gradient is. .... That's on the graph right ? I'll see my self out .
  • 8 1
 Naild. What a load of shit that was. Anyone else remember the designer or someone involved in that project who made burner accounts to post comments defending the design? I do. The bike industry is so damn pathetic sometimes.
  • 2 0
 Darrell Voss.
  • 6 0
 I will wait for Keith Scott of Banshee to chime in. He's the most straight talking suspension designer that I've had the pleasure of listening to or reading from.
  • 2 0
 When I was looking a Prime, I emailed asking and he sent me the graphs. Other manufacturers would give me garbage like it is proprietary information. Love my Prime.
  • 4 0
 If you want to do a better job, ask your boss to buy a telemetry setup. Next time you get a shock for a review, test it on a dyno and post the results. Kinematic graphs are the same as geometry tables, they don't tell the whole story, but they help a lot. And you could post your rides on strava too, just to get an idea on how the test are being made...
  • 6 0
 I have a TI-84 graphing calculator in my bike bag, which I use before I go off any jump.
  • 2 0
 Stoked that Seb stayed away from math in this article, not a good track record.

I ride the Xquareone trail (180mm) and the downhill (218mm) and love riding them because of the high antisquat. Pedaling just doesn't get the bob that I would feel or see on other bikes.
  • 2 0
 You’re a lucky rider. My friend has the 180mm bike and it is just sublime. I haven’t met anyone who has actually spent any decent time on the system have a bad word to say about it. I only hope someone picks it up again in the future.

I’m gutted that I never ended up being able to get one. I’m constantly on the lookout for either one of those second hand. The DH model is my perfect bike. I have no uplift so being able to climb to the top of the trail and still have an amazing ride with all that travel down is pretty valuable to me.
  • 1 0
 @Afterschoolsports: Fully agree. I hope that system at least gets used again in the future. I've built them both pretty light, 29lbs for the 180mm and 32lbs for the DH bike.

It took a little bit for me to find both of mine...found them on PB buy sell. Let me know if you are want any help tracking one down or logistics.

Even though they've sunsetted both models I'm still getting great help from the CS emails. Little odds and ins that I lose or damage.
  • 6 0
 I like when it goes squishy squishy.
  • 6 0
 I came here in hopes of learning something new. Disappointed again.
  • 2 0
 Thanks, nice article - actually that Marin/Polygon bike is a MacPherson strut, or a tweaked version of it. So it's a bit different than 4-bars. I guess it's light damping setup is a consequence of that the thick tube holding the swingarm must have significant friction already, so less oil damping is needed. Anyway good point on the essential importance of the shock. With a mediocre shock you'll never have a suspension that's fine in all cases.
  • 1 0
 With not being able to do good test rides, much less have the opportunity to really dial in the suspension, I find Kinematics and geometry very helpful in choosing a bike. I know what works well for me after years. Moderate progression, as I don’t huck and antisquat in the 110-120% range at sag, as I am lazy with my lockout. Overall leverage ratio on the lower side, as I am a clyde. This also lets me know what shocks are a good match.

It is all about matching the rider to the bike. There is no single set of kinematics that are right. What is perfect for one rider is terrible for another.
  • 1 0
 What current bikes do you like that fit your criteria? I have similar requirements.
  • 1 0
 @ReXTless: Banshee has lower than average LR on their bikes.

RAAW sells two links for their frames, based on your weight.

In general, lower LRs require less dampening and puts less stress on the shock.
  • 1 0
 @ReXTless: Greenblur hit it. Banshee, Privateer and Transition.
  • 1 0
 I think most people want a condensed "this chart tells the whole story" when it comes to kinematics, but two bikes with seemingly identical charts will still ride quite differently. It's all about the subtleties of the LR curve: how much it ramps up and where, not just that it does ramp up; and the actual level of the LR at sag or at average.
I also think Seb hit the nail on the head: the slope of the anti-squat curve. If the anti-squat curve slopes off steeply, you can get a cascading effect of "pedal hard => sag suspension a little => AS goes down so it sags more => AS goes down even more and you sag even more." This does not give a stable response to pedaling!
When you combine the shock spring (whether that's a linear coil or an air spring with any number of volume spacers) with the LR curve, you're able to estimate the wheel rate and the actual travel for a given force input at the wheel. Shocks (even from the same maker) are quite different in their spring profiles so the variability is huge when it comes to how a bike feels (X2 shock with no volume spacers vs. Float X with 0.6ci volume spacer, for instance).
And that's just spring forces! Add damping to the mix in combination with a higher or lower leverage ratio (giving lower or higher damping forces at the wheel, respectively) and the variables are too many to suss out on paper or boil down to one chart or graph. One person could ride two "similar" bikes and they can feel completely different based on these many factors.
  • 1 0
 Thats not how it works regarding the gradient. You cant squat it more that it would squat during your most powerful single pedal stroke, which usually is a first stroke from stationary, anything after that would produce less acceleration, thus less mass transfer and less squat. Also during deadspots in pedal stroke the squatting is reset, unless your rebound is all the way in.
  • 7 2
 The best linkage design site out there: linkagedesign.blogspot.com
  • 1 0
 So if the demping anf type of shock will till more about the bike feel than the kinematics, than how come the Gen1 YT Capra 29 felt stiff and harsh with stock shock, a mrp hazzard with a soft coil at 35% sag and a stiffer coil at 25% sag and an X2 with a soft tune? As soon as the bike picked up some speed and got some repeated medium sized hits it felt like a hard tail - and no - the rebound was not too slow.
  • 3 0
 But then don't I need to be able to compare my COG with that of the reviewer?
  • 1 0
 Yep. But hopefully the geometry of the bike will put it in a useful position anyhow
  • 3 0
 Yeap, the real isdue that renders the antisquat values totally useless is that no one uses the same CoG reference and if a standard is set, it's still useless the reason is suspension diagrams are quite sensitive in the positions of the pivot points and give quite different values even if slightly altered, if you open a linkage program and use all the same values but move the CoG around a few inches, you'll see how drastically all values change.
  • 1 1
 yeti have what we could call a 'regressive chain growth' with the pivot point moving down toward the end of travel making the rear more compliant under pedaling forces past the sag point. At least that sounds a bit more nerdy I hope Smile
  • 3 3
 Some companies get all dentist with the linkages and graphs and 24 little bearings... and others like Orange are just like F$#@ it. , lets all just get rowdy with as little as possible. The only graph that really does matter is the one that spells out that "Party in the woods"
  • 5 4
 I'd love for Seb to go even deeper into suspension leverage kinematics and what that means/feels like on the trail? Why is a 4 bar more plush off the top than a LDSP, etc. etc.
  • 6 3
 Why is a 4 bar more plush off the top than a LDSP?

This is actually one of the easier questions, the key difference is that 4 bar allows you to eliminate brake jack. When braking the brake makes the structural member that the brake is attached to want to rotate in the same direction that the wheel is going. On a LDSP this causes the chainstay to try and rotate which compresses the shock and stops it working as naturally. On a 4 bar the bearing between the chainstay and the seatstay prevents this moment from trying to rotate the seatstay and thus the shock is much less affected by braking
  • 2 0
 @rambotion2: Yea I understand brake jack, but that's not really what I am asking about. Moreso the difference between different suspension platforms through their travel, and diving deeper into how leverage curves translate to the trail, braking/petaling aside. And maybe there aren't significant differences between 4 bar and ldsp outside of brake jack. idk the point is I think its interesting when Seb goes into the weeds of design.
  • 5 0
 @misteraustin: you can make a 4bar or Horst link ride squishy or firm. At least in the US, Specy was the representation of Horst for a long time. They tuned thier bikes with lower AS and linear LRs (up until recently). So for years and years, if you rode a Horst bike in the US, it probably rode soft/active because that's they way Specy tuned it. Hence the reputation.

Same with DW link, typically tuned firm but can be made squishy/soft (Giant, Niner).
  • 2 2
 React to play is honestly the best suspension I’ve ever ridden. Genuinely amazing climbing ability and loads of travel to play with. Like a high pivot bike without the need for an idler, and impeccable climbing behaviour. I was gutted that my local polygon distributor never ended up restocking their bikes.
  • 4 2
 how bout we look at various graphs and talk about characteristics of each graph and what that means, article is way too wordy, not helpful
  • 3 0
 All I want is a simple graph with price on one axis and fun on the other. And laser cats.
  • 2 2
 Kinematics graphs can help inform potential buyers but certainly won't give you the full picture. For example, all these bikes using long clevis yokes connecting to the shock will blow up your shock prematurely and potentially snap the damper shafts. It's even worse if you're a heavier or aggressive rider. At least you can see if a bike has higher or lower leverage rate via the kinematics documentation.
  • 3 0
 I won't buy a bike unless the company makes kinematic information available.
  • 2 2
 All makes sense until you get to the bike reviewers bit...I can tell first hand trying different components especially tyres I've had polar opposite experiences to reviews..the Magic Mary vs Wild Enduro for example...most reviews will have you thinking the Wild Enduro is super draggy and that Addix compounds roll well. I have both tyres back to back the Wild Enduro hands down rolls miles better on asphalt than the Mary along with way better braking traction and much more supportive side knows...yet reviews will say it's draggy and a 7/10. Also had si.ilar experiences with bikes. As far as I'm concerned reviews are about as accurate as the weather forecast...which in Manchester UK...I can say you might aswell roll some dice. The only way to know what is best for you is to try it...especially when it comes to tyres and saddles.
  • 3 4
 Pretty bike, lines !? horrible bike, lady.
I'm a caveman with this stuff, I was wetting myself at 80mm elastomer suspension
back in the day, now it proves pretty shit by todays standards. Being simple and having fun : )
  • 1 3
 Wait what wheres the rest of the article? Was hoping there was some revelation here.. Because honestly alot of leverage curves look the same but a rocker bike will NOT ride like a pull-rod bike. Ride a 70s dirt bike b2b with even a bike from the mid 80s.

I think theres prob some magic in the Evil delta that just isnt in a simple 2d graph informed by pickup points.
  • 1 3
 The Revel/Canfield suspension is basically a single pivot. They say what makes their bikes so good is that the wheelpaths center of curvature stays exactly at the top of the chainring. Thats a single pivot bike. Just saying. I think single pivot bikes are really good with proper leverage ratio/progression though.
  • 2 0
 Thanks for the explanation, though I feel a lot more could be written?
  • 4 3
 Pick an anti and be a d*ck about it
  • 1 0
 I just look at as which frames are plusher and which frames climb better.
  • 2 1
 This thread is useless without laser cats
  • 1 0
 Oh oh... Big brands were knocking the door ....
  • 1 0
 We need more articles like this! Great PB
  • 1 1
 Best thing you can do for your kinematics is replace that junk oem shock.
  • 2 5
 More riding, less talking.





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