Suspension performance: Single pivot Vs everything else (a story of kinematics and acronyms)

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dustyyoungblood

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Without delving deeply into the minor differences between all the multi-link design variations and splitting hairs over anti-squat vs brake jack and pedal platform vs chain growth...... In a broad view of factors you can feel on the trail a single pivot bike has only 1 real performance factor that is a negative when compared to many of the multi-link designs.

1. hard braking over really rough terrain will stiffen the rear ends ability to absorb terrain.

As far as I am concerned that is really the ONLY measurable on trail performance factor that is diminished compared to many other designs.

Anyone debate that?
 
Having had experience on a foes single pivot, specialized fsr, santa cruz & intense vpp, and salsa split pivot. I can tell you that it all boils down to whether or not you need a shock to overcome some of the negatives. The VPP is very good on open or trail mode and you don't need to bother with it when climbing or descending. The single pivot will bob on the climbs if its not locked out, but it is way better descending straight down. Yes rough terrain the suspension stiffens up but that depends on the bike. The single pivot placement has a lot to do with that. Converting from a 2x10 to a 1x10 or 1x11 drastically affects suspension performance and also reduces chain drops. The way single pivot works against chain strain is greatly reduced when the pivot placement is above the chainring.

You could remove nearly all brake jack like by using a float brake system like the Foes Hydro.
 
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Varaxis you' re our only hope...
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I have a horst-style bike (2013 RM Altitude, 150 mm) and a single pivot (2011 transition blindside, set up as a trail bike with a shorter shock and travel, 163 mm). Same shock on both, xfusion vector air. I generally like the blindside's suspension better even though its a single pivot, makes sense since the bike was designed for descending and has a bit more travel. The altitudes suspension feels extremely progresssive and seems to spike at speed, but feels very stable in slow tech and climbs really good. Previously i had a 2011 sanata cruz butcher with a coil shock (single pivot but with vpp leverage curve) felt great everywhere, had a bit of brake stiffening. My favorite bike of all I miss it but i decided to go 650b. Also had a 2010 banshee rune (similar to dw link) and it felt oddd on slow rocky trails, however it did not stiffen up under braking at all. Leverage curve went progressive in fist half, regeressive in second half, didnt work well with the coil shock i put on. the Butcher was much better. Way back I had a 2007 SC heckler, single pivot, great bike. Noit sure what my point is, I think for most recreational riders a well executed single pivot is comparable to a well-executed multipivot, minus a bit of "brake jack."
 
Single pivot's main downside is that it is highly shock tune dependent. By simplifying the frame design, you sacrifice the ability to more finely tune the ride characteristics you desire from the linkage itself.

The gain you get is, well, a more simplified design that is easier to produce and typically more robust, lighter, and less costly to maintain. It can be argued that with the evolution of shocks, single pivots leave little to be desired. Good virtual pivot designs still custom tune their shocks (ex. Yeti, Ibis, Intense, Spec).

Trek, Kona, Scott, Yeti, and many other respectable brands still make great single pivots. It is not at all obsolete. Like most other choices in the engineering world, it's a matter of pros and cons, choosing the best balance for the desired result. There's just a lot of marketing money behind dual link that makes it sell well, and there's high incentive to capitalize on it.

The brake jack stuff is mostly a myth that's been busted long ago (virtually all bikes squat under braking). The stiffen effect is possibly just the suspension staying deep in travel, since the bike is trying to squat (akin to packing up). The amount of "brake anti-rise" (aka brake squat) people like is up to personal tastes. 100% anti-rise offers more stability and is easier to ride faster, but those that do Euro-style nose pivots might like 50% or less (less squat, which makes it easier to endo, and more active under braking).

Generally, with shorter travel bikes (4-5"), you won't notice the benefit of shock tuning nor linkage "magic", as much as you would with a longer travel bike.

Honestly, with some dual links like the Yeti SB infinity, it's essentially a single pivot that has its pivot location rise up and down depending on the position of travel you're currently in (high when cruising/pedaling, low when not).
 
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Varaxis said:
Single pivot's main downside is that it is highly shock tune dependent. By simplifying the frame design, you sacrifice the ability to more finely tune the ride characteristics you desire from the linkage itself.

The gain you get is, well, a more simplified design that is easier to produce and typically more robust, lighter, and less costly to maintain. It can be argued that with the evolution of shocks, single pivots leave little to be desired. Good virtual pivot designs still custom tune their shocks (ex. Yeti, Ibis, Intense, Spec).

Trek, Kona, Scott, Yeti, and many other respectable brands still make great single pivots. It is not at all obsolete. Like most other choices in the engineering world, it's a matter of pros and cons, choosing the best balance for the desired result. There's just a lot of marketing money behind dual link that makes it sell well, and there's high incentive to capitalize on it.

The brake jack stuff is mostly a myth that's been busted long ago (virtually all bikes squat under braking). The stiffen effect is possibly just the suspension staying deep in travel, since the bike is trying to squat (akin to packing up). The amount of "brake anti-rise" (aka brake squat) people like is up to personal tastes. 100% anti-rise offers more stability and is easier to ride faster, but those that do Euro-style nose pivots might like 50% or less (less squat, which makes it easier to endo, and more active under braking).

Generally, with shorter travel bikes (4-5"), you won't notice the benefit of shock tuning nor linkage "magic", as much as you would with a longer travel bike.

Honestly, with some dual links like the Yeti SB infinity, it's essentially a single pivot that has its pivot location rise up and down depending on the position of travel you're currently in (high when cruising/pedaling, low when not).
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:thumbsup:
 
The thing people forget to try and discuss is the level of frame stiffness in each. A cartridge bearing adds a degree of wiggle room, and the longer the arm connected to it, the more it's felt at the end of it. That lack of lateral stiffness people feel sometimes, is probably "tail wag" from the play in bearings. Having more than one set of bearings between the BB and rear axle does not make the rear end stiffer, despite popular belief (ex. short links). They add a lot of extra weight (ex. beefier rear triangle) and expense (ex. angular contact bearings, complex axle systems) to try and cover that up. Imagine the additional tail wag effect if the Yeti Switch Infinity had only 1 rail, instead of two (SI has the same amount of bearings as a single pivot).

Personally, I like Switch Infinity the best, but don't think the $2k or so extra is worth it over a solid horst link or high end single pivot.
 
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My post is biased. My motive is trying to talk myself into a Foes Mixer or Evil over a Santa Cruz hightower. My history being I liked the single pivot bikes I owned (Scott high octane 2005, Commencal 666 2010) and did not really like riding intense 6.6 vpp bike. I liked the giant riegn I owned in 2006. Also. But through all the demos and test rides and friends bikes I have ridden the single pivots feel good.

Since an apples to apples comparison is not really possible, being the shock tuning and leverage rates and desired traits of a particular bike and its intended use/riding style are all part of the suspension design..... Hence the broad overview approach, what is the major downside(if any) of a single pivot 4-6" travel all mountain bike? I say only heavy braking in the rough. Pedal bob, nope. not with 1x and proper shock tune. Maybe standing in a sprint, yes some bob sure.
 
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dustyyoungblood said:
My post is biased. My motive is trying to talk myself into a Foes Mixer or Evil over a Santa Cruz hightower. My history being I liked the single pivot bikes I owned (Scott high octane 2005, Commencal 666 2010) and did not really like riding intense 6.6 vpp bike. I liked the giant riegn I owned in 2006. Also. But through all the demos and test rides and friends bikes I have ridden the single pivots feel good.

Since an apples to apples comparison is not really possible, being the shock tuning and leverage rates and desired traits of a particular bike and its intended use/riding style are all part of the suspension design..... Hence the broad overview approach, what is the major downside(if any) of a single pivot 4-6" travel all mountain bike? I say only heavy braking in the rough. Pedal bob, nope. not with 1x and proper shock tune. Maybe standing in a sprint, yes some bob sure.
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Any single pivot bike with Dave Weagle's "Split Pivot (e.g., Devinci or Salsa) or Trek's "Active Braking Pivot" significantly reduces brake jack. I have been biased toward Trek thanks to Red Shield coverage, but that has been eliminated, so ultimately go for whatever flexes the least during G-outs.
 
DangerDirtyD said:
Any single pivot bike with Dave Weagle's "Split Pivot (e.g., Devinci or Salsa) or Trek's "Active Braking Pivot" significantly reduces brake jack. I have been biased toward Trek thanks to Red Shield coverage, but that has been eliminated, so ultimately go for whatever flexes the least during G-outs.
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I had been looking at Devinci and failed to realize that "Split Pivot" places the brake mounting on the seat stay. That makes sense now. I totally overlooked that detail.
 
I've owned two linkage-driven single pivots (Yeti 575 and Yeti 303 RDH), two modified Horst Link (Knolly Podium and Knolly Endorphin) and two VPP (2007 Santa Cruz V-10 and current Intense Tracer). They were (are) all great. The Knolly is the best descender and climbed the best over chunky terrain - but was a chore climbing smooth surfaces. The 575 did everything well. The Tracer is great when the shock is dialed, but disappointing when the shock/sag is not perfect. Brake jack is a myth. All bikes stiffen under braking. My Podium is the best at absorbing bumps while braking however.

Linkage-driven single pivots visit as many World Cup podiums as any other design.

So, bottom line, get whatever floats your boat. They are all fantastic, and all have their own personality quirks. Take time to dial in your suspension.
 
Whatever this is, it was under the 1st, 2nd and 3rd place finishers in the 2016 UCI World Championships DH in Andorra.

Summum Frame.jpg


Looks like a mini-link such as Maestro/DW/VPP entirely separating the rear triangle from the front. Certainly not a linkage-driven single pivot.

Here's what Mondraker says. It sounds very impressive to me.

Zero is a dual link design with the shock floating between the two suspension links and compressed from both ends. This makes the rear suspension extremely sensitive on small bumps and big hit capable.

Zero superior technologies’ main advantages are Zero power loss -a completely stable ride when pedaling-, Zero pedal kickback-minimum chain growth throughout the suspension travel-, Zero brake jack –isolated braking and suspension forces- and what we call Zero bumps, its great ability to soak up any type of bump keeping the rear wheel efficiently planted on the ground.
 
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Varaxis said:
The thing people forget to try and discuss is the level of frame stiffness in each. A cartridge bearing adds a degree of wiggle room, and the longer the arm connected to it, the more it's felt at the end of it. That lack of lateral stiffness people feel sometimes, is probably "tail wag" from the play in bearings. Having more than one set of bearings between the BB and rear axle does not make the rear end stiffer, despite popular belief (ex. short links). They add a lot of extra weight (ex. beefier rear triangle) and expense (ex. angular contact bearings, complex axle systems) to try and cover that up. Imagine the additional tail wag effect if the Yeti Switch Infinity had only 1 rail, instead of two (SI has the same amount of bearings as a single pivot).

Personally, I like Switch Infinity the best, but don't think the $2k or so extra is worth it over a solid horst link or high end single pivot.
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Thanks varaxis! You never disappoint!
 
You can apply whatever name to it that you wish. Brake jack may not be the correct term, but unless single pivots have a floating caliper (at least the ones I have been on) they suck harder when braking on steep bumpy descents than something like the Maestro suspension I had on my Giant Reign. Pretty damn good if you don't need the brakes while descending the rough stuff, but that isn't the world I live in. YWMV.
 
V brakes, disc brakes, floating brakes, coaster brakes, even flintstone brakes, with no suspension, front susp only, full suspension... braking forces still result in an opposing force that wants to "torque" (or rotate) the bike, essentially endo'ing you. Doesn't matter if you're using the front, or rear brake--both result in your body mass being shifting forward. Though, in reality, the rear brake on a bike can't endo you, due to the forward weight shift lifting the rear tire off the ground, which eliminates any further braking/endo force (the physics of a skid).

The rear linkage can absorb some of this forward weight shift. Just like pedaling can pull a chain forward, which pulls the rear swingarm to extend (or compress) the suspension, the rear suspension is connected in a way that the forward weight shift also can either extend or compress (or be relatively neutral). It's called anti-squat for pedaling, and it's called brake anti-rise (or brake squat) for braking. Low levels of anti-rise leads to more endo-prone feeling under braking (death gripping, ass behind saddle), but the suspension is more active/independent and free to do its job. Negative anti-rise leads to brake jack, which extends the suspension and lifts the bike, actually making the endo-prone force stronger (super rare, some Liteville bikes). 100% anti-rise absorbs the braking "endo-force" entirely, but tends to work against your suspension's rebound forces, and leads to a harsher ride (shock packing up), though makes the bike easier to ride. Higher than 100% makes the bike squat even more under braking.

Trivia: Fabien Barel was a world champion DH racer who demanded more brake squat on his bike (Kona). He believed that since he was already pointed downslope on his bike, making the bike feel more level with the front stiff and propped high, and rear deep in its travel, it felt much more stable in steep sections and easier to keep it moving forward. The DOPE system was tweaked to tune it to his demands.

Think of the bikes that you OTB'd most on, and they might be bikes without rear suspension and/or bikes with low brake anti-rise (ex. Horst link bikes, Ellsworth in particular), especially smaller diameter-wheeled bikes.
 
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Varaxis said:
V brakes, disc brakes, floating brakes, coaster brakes, even flintstone brakes, with no suspension, front susp only, full suspension... braking forces still result in an opposing force that wants to "torque" (or rotate) the bike, essentially endo'ing you. Doesn't matter if you're using the front, or rear brake--both result in your body mass being shifting forward. Though, in reality, the rear brake on a bike can't endo you, due to the forward weight shift lifting the rear tire off the ground, which eliminates any further braking/endo force (the physics of a skid).

The rear linkage can absorb some of this forward weight shift. Just like pedaling can pull a chain forward, which pulls the rear swingarm to extend (or compress) the suspension, the rear suspension is connected in a way that the forward weight shift also can either extend or compress (or be relatively neutral). It's called anti-squat for pedaling, and it's called brake anti-rise (or brake squat) for braking. Low levels of anti-rise leads to more endo-prone feeling under braking (death gripping, ass behind saddle), but the suspension is more active/independent and free to do its job. Negative anti-rise leads to brake jack, which extends the suspension and lifts the bike, actually making the endo-prone force stronger (super rare, some Liteville bikes). 100% anti-rise absorbs the braking "endo-force" entirely, but tends to work against your suspension's rebound forces, and leads to a harsher ride (shock packing up), though makes the bike easier to ride. Higher than 100% makes the bike squat even more under braking.

Trivia: Fabien Barel was a world champion DH racer who demanded more brake squat on his bike (Kona). He believed that since he was already pointed downslope on his bike, making the bike feel more level with the front stiff and propped high, and rear deep in its travel, it felt much more stable in steep sections and easier to keep it moving forward. The DOPE system was tweaked to tune it to his demands.

Think of the bikes that you OTB'd most on, and they might be bikes without rear suspension and/or bikes with low brake anti-rise (ex. Horst link bikes, Ellsworth in particular), especially smaller diameter-wheeled bikes.
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The resident speaks! Thanks Dan!
 
Torrent77 said:
I've not had a bike that stops as well as a split pivot. Rough terrain, loose, loamy, under load, or any circumstance the rear tire makes constant positive contact with the surface without pedal kickback.
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Tires, tire pressure, rider position, geometry, and damper tune each benefits that sort of braking performance far more than the linkage design does.

This whole thread's point actually is about how people are misled to believing that bicycle suspension systems are/aren't responsible for certain characteristics, when it's essentially only really responsible for managing the up-and-down movement of the rear wheel. My legs and my ass do a good job of keeping the rear tire in contact with the ground on my hardtail, which is what a proper suspension system should be doing...

Rear suspension has been a double edged sword. You want it to do similar work that your legs and body would've, but don't want it to behave badly, such as when you're climbing out of the saddle. There's been all sorts of "design strategies" to get this done--the results speak for themselves, being proven at the highest levels of the sport. There's a serious lack of DW-link style systems winning top level XC races, and simpler suspension linkages like single pivots (Trek, Devinci, Kona) and Horst link are performing just fine on DH course. Simply put, there's no inferior/superior system; there's only good and bad design execution. I think people are just fooling themselves and subconsciously driving the marketing/hype machine for this stuff...

I don't put value in such subjective opinions, such as your experience on your split pivot, since there's only so much a person can sense accurately, and there's so many unknown variables which must be examined before I can personally draw a conclusion. Unless the nerves under your skin can be used to calibrate load cells, I'm just going to heap on a bunch of salt on your opinion and respond with a correspondingly salty reply... if you instead said that your [specific bike model, spec] had such braking performance, instead of "split pivot", then I'd take note.

I'm not taking a side, single pivot vs multi, as internet consensus demands, but if I must, I'll take the side of being educated over being foolish/ignorant.
 
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Varaxis said:
Tire, tire pressure, rider position, geometry, and damper tune each benefits that sort of braking performance far more than the linkage design does.

This whole thread's point actually is about how people are misled to believing that bicycle suspension systems are/aren't responsible for certain characteristics, when it's essentially only really responsible for managing the up-and-down movement of the rear wheel.
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I respectfully disagree with this. I come from a racing background and I can tell you that suspension kinematics and swingarm design plays just as crucial part in overall performance. Tire pressure, tire tread design, tire lay up, unsprung weight, dampner tuning, dampner leverage can be used to either enhance or overcome limitations/optimization in a bike suspension design. A solid axle and IRS also does the same up/down movement, but you can't say they both perform the same.
 
What are you disagreeing with exactly? You are saying the linkage benefits more than tires, tire pressure, rider position, geo, and damper tune when braking?

Think about that... are you seriously trying to argue this? With that kind of support, that half-agrees with me? Ok, would you take IRS + street tires and highway cruising geo over solid axle (spring weight tuned for each course), racing tires, and racing geo (ex. shorter wheelbase), on a variety of demanding courses that pushes the limits of man and machine?

Once you think about it, it should be clear that suspension linkage design doesn't rank very high on the list of "must-have" things. I presume that average people sweat it, because all the nicest bikes seem to have the same stuff bolted onto them, leaving only the frame and suspension design to be the difference (besides the riders themselves). That and I guess that they enjoy casually discussing how they believe such mysteries work...
 
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