Mountain bike rear suspension: the ultimate phrase info

Full-suspension mountain bikes can use single or a lot of pivot locations, fully completely different linkages and swingarm designs to help dictate their suspension traits.

What variety of pivots and hyperlinks are used and the way in which they’re laid out helps to learn how the bike will work, the way in which it’ll actually really feel on the trail and how much utilizing it might be biggest suited to.

Proper right here we make clear the various sorts of mountain bike rear suspension, the technical phrases used to elucidate suspension kinematics and the way in which bike producers regulate or change their suspension designs to create specific suspension traits. 

You probably can skip to the fully completely different sections by hitting the hyperlinks beneath:

How do suspension designs impact a motorbike’s effectivity?

Although rear-suspension design can differ vastly from mannequin to mannequin, the job is on a regular basis primarily the an identical: to absorb bumps and impacts as successfully and efficiently as attainable.

The truth is, it’s considerably additional difficult, because of the suspension ought to accommodate the rider transferring about on excessive of the bike, pedalling and braking whereas navigating the trail beneath their tyres. Suspension designs must problem all of this stuff in.

Have an effect on absorption

The first job of a rear suspension system is to absorb impression forces attributable to the rear wheel hitting a bump or obstacle, which causes the suspension to compress.

A motorcycle’s potential to absorb an impression is principally influenced by a lot of parts:

• The axle path is the street the rear axle traces as a result of the suspension cycles through its journey. Axle paths might be forward, vertical, reward or S-shaped. Its path is dictated by the place of the physique’s pivot components.
• Pivot locations dictate the axle’s path at a given degree throughout the journey.
• Leverage ratio/curve is the connection between how rather a lot the rear wheel strikes and the way in which rather a lot the shock compresses as a result of the suspension cycles. As an illustration, if a motorbike’s frequent leverage ratio is 3:1, when the rear axle strikes 30mm, the shock will compress by 10mm.
  The leverage ratio can change all by means of the bike’s journey (producers will plot this on a leverage curve graph for instance how this changes). That’s arguably additional important than the frequent leverage ratio.
  Starting with a extreme leverage ratio means the shock might be compressed additional merely, offering additional preliminary sensitivity and possibly additional grip. Within the course of the tip of the journey, a lower leverage ratio helps to up the amount of energy required to compress the shock, rising the extent of improvement and making it extra sturdy to bottom out (use all of the suspension journey)
• Shock absorber and spring. With out these, the suspension system can’t soak up impacts. Springs current the resistance to absorb the compression forces from an impression and rebound or return the suspension system to its distinctive, uncompressed (or sagged) place.
  Nearly all rear shocks will operate some sort of in-built damping. This controls the tempo at which the shock compresses and rebounds, typically by pushing oil through a set of ports and shims to create resistance. With none sort of damping, the spring would oscillate uncontrollably.

Widespread suspension designs outlined

Now we understand what a mountain bike suspension system is supposed to do, and the varied components that have an effect on the way in which it performs, let’s take a look on the major suspension designs within the market.

We’ll moreover outline the professionals and cons of each. 

Single pivot

The one pivot is the one suspension design in use within the current day.

Proper right here, the rear axle is expounded to the first physique by a swingarm, with no additional pivots in between. The axle strikes in a seamless arc, centred on the one pivot degree.

Throughout the case of an actual single pivot, the shock is expounded on to the swingarm – a design made well-known by Orange Bikes.

One attainable shortcoming of this design is that it affords little administration over the leverage curve.

True single-pivot bikes are often pretty linear. The facility required to maneuver the rear wheel through its journey would not ‘ramp up’ within the course of the tip of the physique’s journey to face up to bottom-out, because it may with a additional progressive design.

Professionals

• Straightforward
• Requires fewer bearings and makes for less complicated repairs
• The suspension movement is fixed through its journey

Cons

• Presents little administration over the leverage curve
• Could possibly be too linear for coil shocks

Linkage-driven single pivot

A linkage-driven single-pivot design, as seen on the Marin Rift Zone, nonetheless makes use of an uninterrupted swingarm, connecting the rear axle on to the mainframe. 

Nonetheless, it incorporates some sort of linkage to drive the shock. This enables the physique designers to control the leverage curve and administration the physique’s progressivity.

The design seems very similar to a four-bar (Horst-link) design, so is usually generally known as ‘faux-bar’. Nonetheless the rear axle continues to be immediately associated to the first pivot by means of the chainstay, so that’s merely one different sort of linkage-driven single pivot.

Professionals

• Additional leverage curve tunability than an actual single-pivot MTB

Cons

• Elevated repairs over single pivot
• Mounted immediate centre limits the tuning of some suspension traits

Trek ABP and DW split-pivot applications

This design is principally a linkage-driven single pivot, moreover that Trek makes use of a concentric dropout pivot on the rear axle. This enables Trek to mount the brake caliper to the seatstay pretty than the chainstay.

On account of the seatstays rotate a lot much less throughout the disc rotor than the chainstays as a result of the suspension cycles, the influence of anti-rise is significantly lowered.

In several phrases, Trek’s design works like a linkage-driven single pivot relating to pedalling forces, nevertheless like a Horst-link relating to braking forces. It’s one factor of a hybrid.

Professionals

• Significantly lowered anti-rise

Cons

• Elevated repairs over single pivot

Extreme pivot

Extreme-pivot bikes have a pivot degree positioned rather a lot bigger than common, nevertheless transferring the pivot bigger alone would result in unacceptably extreme ranges of pedal kickback.

Using an idler pulley, which routes the chainline up earlier the pivot degree, would possibly assist to mitigate pedal kickback and be used to tune anti-squat traits. 

Some nice advantages of this design are two-fold. First, it provides a rearward axle path. This in itself would possibly assist the rear wheel to deal with square-edge hits and contributes to the final pedalling effectivity of the bike. 

Second, because of the chain passes correct by the pivot degree, there could also be subsequent to no pedal kickback. This extra improves suspension sensitivity.

Potential disadvantages of high-pivot designs might embody elevated drivetrain drag and maintenance due to the idler pulley, and some designs may have extreme ranges of anti-rise because of extreme pivot degree. 

Completely different designs need longer chains to accommodate the idler’s location, in all probability together with value and weight. Plus the rear centre grows all through compression (by varied portions, counting on the design used), in all probability creating unusual coping with traits.

Professionals

• The rearward axle path helps the bike maintain momentum over square-edge impacts
• Very low ranges of pedal kickback

Cons

• Elevated repairs
• Potential for drivetrain drag
• Extreme ranges of anti-rise in some conditions
• Rear centre will improve in measurement, producing odd coping with traits
• Some designs need longer chains than commonplace suspension applications

Horst-link (four-bar)

Horst-link (typically generally known as four-bar) suspension – utilized by Specialised, Norco and loads of additional – is marked out by a rear pivot positioned beneath and in entrance of the rear axle on the chainstay.

This means the rear axle is not going to be immediately associated to the mainframe, and so it strikes in a path outlined by its immediate centre and centre of curvature.

The second centre and centre of curvature may switch as a result of the suspension cycles through its journey. 

Counting on the design, the influence of braking forces on the suspension (anti-rise) might be lowered and administration over the levels of anti-squat might be elevated, relative to a single-pivot design. 

A variation of the Horst-link might be found on the high-pivot Forbidden Druid, which flips the four-bar system the unsuitable manner up.

Professionals

• Presents extreme ranges of tunability of all suspension traits and predictable suspension curves

Cons

• Additional pivots to maintain as compared with a single-pivot design

Twin-link (digital pivot)

Twin-link designs, typically generally known as digital pivots, use a rigid rear triangle, which articulates on a pair of fast hyperlinks connecting it to the mainframe. 

It actually works in an identical method to a Horst-link design. Take into consideration transferring the Horst-link’s chainstay pivot rather a lot nearer to the mainframe and you have the premise of a twin-link system. The one precise distinction is the dimensions of the lower hyperlink.

As with the Horst-link design, the axle course of a twin-link system is tangential to a transferring immediate centre, whereas centre of curvature, or ‘digital pivot degree’, defines the way in which wherein throughout which the axle path curves through its journey. 

Some twin-link designs, equivalent to Santa Cruz’s VPP system, use hyperlinks that counter-rotate (flip in reverse directions), whereas many others, equivalent to Massive’s Maestro system, have hyperlinks that co-rotate (flip within the an identical course). 

One of the best ways the centre of curvature migrates as a result of the bike strikes through its journey is form of fully completely different for each configuration.

In fact, twin-link or Horst-link bikes with co-rotating hyperlinks sometimes exhibit anti-squat behaviour that’s much like a single-pivot bike. 

Counter-rotating hyperlinks can produce an anti-squat profile that peaks in the midst of the journey, which may be fascinating relating to balancing pedal effectivity in direction of pedal kickback. 

This distinction between counter-rotating and co-rotating hyperlinks is additional important relating to suspension kinematics than the arbitrary distinction between Horst-link and twin-link designs. 

Professionals

• Presents extreme ranges of tunability of all suspension traits and predicable suspension curves

Cons

• Elevated repairs and costs over single pivot

Six-bar suspension designs 

Until simply currently multi-link six-bar suspension designs have been comparatively uncommon, nevertheless bikes equivalent to Felt’s Equilink present the design has been used for pretty some time.

Producers equivalent to Atherton Bikes, Commencal and Yeti have been behind a resurgence of the six-bar design, inserting it once more throughout the limelight. 

In some examples, such as a result of the Canyon Sender, and Specialised’s Enduro and Kenevo SL, the bike’s immediate centre is printed by the first four-bar system. The shock is pushed from a separate linkage system, taking the final number of hyperlinks to six.

Wanting fastidiously on the linkage design seen on Atherton Bikes and Commencal, the extra two hyperlinks are in between the chainstay and the first physique.

Professionals

• Presents extreme ranges of tunability of all suspension traits and predictable leverage curves

Cons

• Elevated repairs over single pivot

Yeti Swap Infinity

This technique makes use of a low pivot, which slides up and down on a pair of vertical shafts, along with an larger hyperlink that rotates clockwise (if thought of from the driveside) as a result of the suspension compresses.

The lower pivot acts similar to the rear pivot on the lower hyperlink of a traditional twin-link design, moreover that this pivot strikes vertically in a straight line pretty than a curving arc centred on the forward pivot degree.

Take into consideration you would possibly make the lower hyperlink of a regular twin-link bike infinitely prolonged and horizontal. Then its rear-pivot location would switch up and down in a straight, vertical line with no curvature to its path the least bit. That’s primarily what Yeti has simulated with its linear sliders (subsequently the establish).

What’s the aim of that? Properly, Yeti claims this enables it to get the kinematics to behave the way in which it wishes all by means of the journey.

On paper, a minimal of, there’s nothing drastically fully completely different about Yeti’s suspension kinematics as compared with some frequent twin-link designs. 

Although it has managed to increase the anti-squat throughout the sag degree the place it’s wished most, it then drops off drastically deeper into the journey to minimise pedal kickback, allowing the suspension to work additional freely. 

We uncover this trade-off throughout the anti-squat and pedal kickback sections of this textual content. Nonetheless, it’s not true that the Swap Infinity design has a really unusual or rearward axle path, as some media outlets may have claimed.

Professionals

• Anti-squat peaks within the course of sag degree
• Pedal kickback lowered deeper in journey 

Cons

• Elevated repairs over single pivot

Mountain bike suspension phrases outlined

What’s a suspension linkage?

A suspension bar or linkage is a rigid half contained in the suspension system that is associated to its completely different parts with pivots.

To calculate the number of bars in a suspension design, you will have to solely rely these hyperlinks that define the system’s axle path, anti-squat and anti-rise.

A physique’s entrance triangle have for use when calculating the number of bars; the other bars are hooked as much as it and their movement is printed by it.

As a result of this reality, single-pivot bikes are two-bar designs. Horst-link or twin-link bikes are four-bar designs, and DW6 (found on Atherton Bikes) or Yeti Sixfinity designs (seen on the Yeti 160E) are six-bar layouts.

Bikes that use additional linkages to handle suspension-leverage fees – equivalent to faux-bar bikes (single pivots with a linkage) aren’t true four-bar designs.

The Specialised Enduro (a four-bar design with an extra two hyperlinks to stipulate kinematics) isn’t an actual six-bar design whatever the suspension having six hyperlinks.

What is the immediate centre?

Immediate centre (IC) dictates the path throughout which the rear axle, wheel and all of the items hooked as much as it, switch at a given degree throughout the journey. 

For single-pivot bikes (along with linkage-driven varieties), the IC is solely the first pivot degree. It doesn’t switch; it’s mounted on the mainframe. As a result of this reality, the rear axle is constrained to maneuver in a seamless arc centred on the pivot.

In a Horst-link or twin-link design, the second centre ‘floats’ on the extent of intersection of hypothetical traces drawn through the pivots of the two hyperlinks, which can be associated to the mainframe. As a result of the suspension cycles through its journey, the second centre strikes.

The position of the second centre helps define the levels of anti-squat, pedal-kickback and anti-rise at a given degree throughout the journey.

On account of the second centre strikes as a result of the suspension cycles through its journey, Horst-link, twin-link or six-bar designs afford their designers higher administration over these parameters all by means of the journey.

What is the centre of curvature?

The centre of curvature (CC) is the environment friendly pivot degree of a twin-link or Horst-link design.

Take into consideration a drawing compass the place the rear axle acts as a result of the pencil and the CC is the sharp degree caught into the paper – it defines the radius of curvature of the axle path.

Must you draw a line from the axle to the IC, then switch the axle a small amount through the journey, then draw that axle-to-IC line as soon as extra, the aim at which these traces intersect is the CC.

For single-pivot bikes, the CC is on the main pivot degree, which may be the IC. For twin-link or Horst-link bikes, the IC strikes relative to the mainframe. In some cases, the CC strikes too. In others, it doesn’t.

For bikes with hyperlinks that counter-rotate (e.g. VPP), the CC strikes significantly. This results in varied curvature of the axle path, and anti-squat values which may be tuned to peak someplace in the midst of the journey differ. 

At a given degree throughout the journey, the CC on a regular basis sits in some unspecified time sooner or later alongside the swingarm line, connecting the rear axle to the IC. 

As a result of this reality, when calculating anti-squat at a given degree throughout the journey (see beneath), the IC or the CC may be utilized interchangeably, because of they every agree on the tangential course of the axle. 

Nonetheless to see how the anti-squat changes all by means of the journey, the place and movement of the CC is beneficial to take a look at.  

What’s pedal bob?

Counting on the form of utilizing the bike is designed for, suspension applications might be designed to produce a company pedalling platform or prioritise suspension effectivity. 

The diploma to which that’s prioritised over impression absorption and braking effectivity relies upon upon the supposed use of the bike. A cross-country bike will prioritise a firmer pedalling platform over fine-tuned impression absorption, whereas an enduro bike would put additional emphasis on the latter.

Every time you push down on the pedals, the bike accelerates. This acceleration causes your weight to shift backwards and compresses the rear suspension – an identical to in an accelerating car.

This happens with the rhythmic nature of every pedal stroke, so the bike’s suspension oscillates, or bobs, as you pedal. This oscillation known as pedal-bob.

This movement wastes energy; the suspension dampers convert this energy into heat pretty than propelling the bike forward.

As a result of the rider locations weight on the pedals, they exert a downward energy on the underside bracket. This causes the suspension to compress, so the underside bracket strikes downwards as a result of the pedals transfer three and 9 o’clock, after which it rebounds once more up as they attain six and 12 o’clock.

So within the occasion you moved with the bike and regarded on the cranks from the side, the pedals wouldn’t switch in a circle, they’d switch in an elliptical (oval) path because of the underside bracket strikes up and down as a result of the cranks flip.

This means the rider has to push the pedals further per revolution than they could if there was no pedal bob, however the rear wheel nonetheless turns the an identical amount. This additional distance is proportional to the wasted energy.

Anti-squat

Similtaneously pedal-bob, pedalling forces pull on the chain. This, in flip, influences the rear suspension, extending it and lifting the rider. 

Anti-squat is a measure of how rather a lot the suspension resists pedal bob. As a result of the squat energy (ensuing from acceleration) compresses the rear suspension beneath power, the anti-squat energy counteracts this.

This energy comes from two sources: the driving energy from the rear wheel and the chain-pull energy.

The driving energy is talked about little, nevertheless it is easy ample to know.

For any bike, take into account the environment friendly swingarm as a straight line connecting the rear axle to the second centre. That is known as the swingarm line. By definition, this line may even transfer through the centre of curvature, nevertheless for simplicity, we’ll merely talk about with the IC proper right here.

The driving energy pushes through the swingarm line. The facility consists of the traction energy propelling the bike forward, plus the compressive energy generated by the chain stress.

If the second centre is bigger than the rear axle – so the swingarm line is angled upwards – part of this driving energy acts to push the mainframe upwards when pedalling, counteracting its tendency to squat down beneath acceleration.

The chain-pull energy comes from the stress throughout the chain, which often moreover pulls the rear wheel downwards relative to the mainframe, and so acts to hold the mainframe up, countering its tendency to squat beneath pedalling load.

Pondering of it one different technique, (for a lot of bikes) the cassette strikes up and away from the chainring as a result of the suspension compresses, because of this reality the stress throughout the chain resists this motion by pulling the swingarm down.

The amount of anti-squat energy relies upon upon the angle of the swingarm line, whereas the amount of chain-pull anti-squat relies upon upon the angle of the chainline relative to the swingarm line. 

The total amount of anti-squat might be labored out by the intersection of the swingarm line and the upper chainline.

The aim the place they intersect is the essential factor. A third line can then be drawn from the rear contact patch through this degree of intersection. That is known as the anti-squat vector, and its gradient defines the amount of anti-squat.

Evaluating this line to the centre of gravity and the doorway contact patch tells you methods the anti-squat energy compares to the squat energy ensuing from acceleration. In simplistic phrases, 100 per cent anti-squat would counsel that the squat and anti-squat forces cancel out exactly.  In idea, this results in zero pedal bob.

If the anti-squat vector is bigger than the centre of gravity when it’s immediately above the doorway contact patch, you have gotten higher than 100 per cent anti-squat. If it’s beneath the COG when it’s above the doorway axle, you have gotten decrease than 100 per cent anti-squat.

Importantly, the anti-squat share is unbiased of how arduous you pedal. Must you pedalled twice as arduous, you’d pace up twice as fast, and so the squat energy would double. On the an identical time, the anti-squat energy would double because of there may be double the stress throughout the chain. So the anti-squat share would keep the an identical. 

So why aren’t all bikes designed to have 100 per cent anti-squat? Wouldn’t that suggest an end to pedal bob? Properly, as you might have guessed by now, it’s not that straightforward.

For starters, there is no such thing as a such factor as a method to exactly estimate the place of the rider’s centre of gravity (it varies counting on the rider and the way in which they switch about when utilizing).

Even within the occasion you could estimate the rider’s centre of gravity, the place of the bike’s entrance centre impacts the share of anti-squat. That changes with the physique dimension, so that you just’d must account for that too. Most bike designers don’t.

For a lot of bikes, the amount of anti-squat moreover relies upon upon what gear you’re in.

The exception to that’s the case of a motorbike the place the CC is exactly per the very best of the chainring. In another case, the number of rear sprocket will give fully completely different portions of anti-squat, because of the intersection of the chainline and the swingarm line will change.

Completely completely different chainrings upset points too, with smaller chainrings resulting in bigger anti-squat. That’s an argument in favour of a lot of chainrings, because of bigger anti-squat is often helpful when climbing.

One different complication is that, for a lot of bikes, the levels of anti-squat vary as a result of the bike strikes through its journey – usually by fairly a bit – so how rather a lot dynamic sag you run will impact anti-squat and because of this reality pedalling effectivity.

So altering spring pressures, or utilizing up fully completely different gradients, will result in fully completely different anti-squat percentages.

Let’s take into consideration for a minute that you just would possibly design for one physique dimension, one gear, one degree throughout the journey, and for a rider whose centre of gravity was mounted.

In that case, you would possibly design a motorbike to face up to squat exactly, if the power was utilized simply by means of a motor. That’s why it is attainable, although not basically advantageous, to design a motorcycle that resists acceleration-induced squat practically completely.

Nonetheless mountain bikes mustn’t motorbikes. When pedalling, a rider’s weight strikes up and down barely as their legs flip. This introduces one different oscillation-driving energy, which causes the bike to bob higher than the acceleration energy alone, significantly when pedalling standing up.

Due to this, many bikes have higher than 100 per cent anti-squat to help counter the blended squat forces from acceleration and the rider’s weight movement.

On account of downhill bikes are designed to be pedalled standing up solely, they sometimes have anti-squat ranges far bigger than 100 per cent. 

In idea, within the occasion you could pedal fully simply with out jerking up and down, bikes with higher than 100 per cent anti-squat would rise upwards, like an inchworm, pretty than squat down when pedalling. This has led some suspension analysts to say that 100 per cent anti-squat is the right amount for the perfect effectivity. 

Nonetheless the jerky physique weight actions of the rider suggest bikes desire a bit additional anti-squat to beat this. On account of this energy changes counting on the rider’s pedalling style, and isn’t basically in part with the acceleration squat energy, there’s no method to say what the most effective anti-squat value is. 

So don’t be fooled by any marketeer claiming their bike has “optimised pedalling effectivity”. It’s moderately tougher than that.

Pedal kickback

There may be often a draw again to extreme ranges of anti-squat. The anti-squat energy depends upon the cassette transferring away from the chainring as a result of the suspension compresses. That is known as chain improvement. 

As a rule, the cassette rotates forward to allow the chain ample slack for the suspension to compress.

Nonetheless, if the cassette can’t spin forward because of the rear wheel is locked up (beneath heavy braking, as an illustration), the crank is perhaps compelled to rotate backwards. 

The movement of the crank throughout the case of a non-rotating cassette known as pedal kickback, which could set off a very harsh journey actually really feel.

The additional chain-pull anti-squat a motorbike has, the additional pedal kickback it generates. These phrases can roughly be thought of two names for the same issue. 

For single-pivot bikes with an immediate centre that’s bigger than excessive of the chainring (as an illustration, high-pivot bikes with out an idler pulley), the amount of pedal kickback is proportional to the anti-squat.

For bikes with extreme pedal-kickback values, its influence can typically flip into noticeable – significantly on robust tracks with loads of sudden impacts or when hitting bumps with the rear wheel locked up.

It may be felt when climbing. As a result of the chain is on a regular basis beneath stress when pedalling, the anti-squat by definition, resists the suspension’s movement. So bikes with extreme anti-squat might be harsh and unreactive when pedalling over bumps.

In numerous utilizing circumstances, pedal kickback in itself is not going to be one factor you’re susceptible to find.

Nonetheless the additional chain improvement/pedal kickback you have gotten, the additional the chain, cassette and derailleur cage must maneuver to have the ability to allow the suspension ample slack throughout the chain to react. This may have a detrimental influence on suspension sensitivity, significantly when using a clutch derailleur.

So there’s a stability to be struck proper right here: additional anti-squat often means higher pedal-efficiency, nevertheless tends to suggest worse sensitivity.

That’s the place Horst-link and twin-link designs have a doable profit over single-pivot applications.

All such designs operate immediate centres that migrate as a result of the suspension strikes through its journey.

Some, considerably these with counter-rotating hyperlinks, might be designed such that the centre of curvature migrates significantly as successfully. In that case, the angle of the swingarm line varies with journey in a technique that isn’t attainable with a single-pivot design. 

This makes it attainable to have extreme ranges of anti-squat near the sag degree (the place it’s wished to face up to bob), whereas having a lot much less anti-squat, and because of this reality a lot much less pedal kickback, elsewhere throughout the journey.

That’s not at all true of all multi-link bikes, nevertheless these with counter-rotating hyperlinks boast anti-squat values that peak between 20 and 45 per cent journey the place it’s wished most.

This bell-shaped anti-squat profile is typical of twin or Horst-link designs with counter-rotating hyperlinks. The result is good pedalling effectivity all by means of the pedalling zone, with minimal additional pedal kickback further into the journey. 

There are moreover similarities throughout the anti-squat profile between some single-pivot and twin-link bikes. 

In cases the place the hyperlinks co-rotate, the centre of curvature doesn’t switch significantly relative to the mainframe all by means of the journey. This means the rear axle strikes in an arc with a seamless radius in regards to the CC, similar to a single-pivot, resulting in comparable anti-squat behaviour. Particularly, the anti-squat typically drops off all by means of the stroke. 

The steeper the anti-squat drops off, the a lot much less pedal kickback there is perhaps within the course of the tip of the stroke, nevertheless the additional the pedalling effectivity is perhaps affected by dynamic sag.

Nonetheless, the centre of curvature might be designed to sit down down prepared which is perhaps impractical to place a bodily pivot (equivalent to contained in the radius of the wheel, or in the midst of the doorway triangle).

On this sense, the designers can produce kinematic behaviour which is perhaps robust, in observe, to repeat with a single pivot.

With out redesigning your bike, you can tune the amount of anti-squat it has by swapping chainrings. Bigger rings will result in lowered anti-squat nevertheless a lot much less pedal kickback, or vice versa. 

Additional merely, utilizing over robust terrain throughout the smaller cassette cogs (and bigger chainrings in case you may have a lot of) will result in a lot much less pedal kickback. So shift into the extra sturdy gears sooner than dropping proper into a tricky descent for max sensitivity and minimal recommendations.

Extreme-pivot bikes bypass this. The idler means they exhibit nearly zero upper-chain improvement or pedal kickback. However, because of extreme IC, they nonetheless have important ranges of anti-squat due to the driving energy alone.

What’s anti-rise (or brake jack)?

One different concept that impacts suspension effectivity is anti-rise, generally called brake jack. That’s principally the influence of the rear brake energy on the suspension. It actually works a bit like anti-squat nevertheless in reverse.

Beneath braking, the rider’s weight shifts forward ensuing from deceleration, which causes the rear suspension to rise or delay. Nonetheless, the ability going through the rear brake caliper acts to compress the suspension, pushing the mainframe down. This resists the bike’s pure tendency to want to increase on the rear, so it stays additional diploma beneath braking.

Must you compress the rear suspension whereas the rear wheel stays nonetheless, the caliper will switch spherical relative to the disc. Must you pull the rear brake when utilizing forwards, the braking torque from the caliper acts to compress the suspension by an amount proportional to this movement, relative to the disc.

The amount of anti-rise relies upon upon the extent to which the caliper wishes to maneuver throughout the disc and this relies upon the place of the second centre.

Take into consideration a line between the rear contact patch and the IC: the shallower the gradient of that line, the lower the amount of anti-rise. That’s known as the anti-rise vector and may be utilized to calculate the share anti-rise within the an identical technique as a result of the anti-squat vector throughout the diagram above.

Proper right here, higher than 100 per cent anti-rise implies that pulling the rear brake solely would set off the rear suspension to compress, whereas decrease than 100 per cent anti-rise implies it may delay.

Horst-link or twin-link bikes with roughly parallel hyperlinks have an immediate centre that’s very far forward.

As a result of this reality, the anti-rise vector sits at a shallow angle, resulting in low ranges of anti-rise. Bikes with immediate centres positioned extreme up and rearward have additional anti-rise.

Trek’s ABP design sees the brake caliper hooked as much as the seatstay, pretty than the chainstay. The seatstay strikes on an arc that’s outlined by a floating immediate centre, like a Horst-link, which is further forward of the first pivot, so anti-rise is lowered relative to a chainstay-mounted caliper.

Brake arms have been used to comparable influence – they reduce anti-rise by limiting the brake’s influence on the suspension.

Extreme ranges of anti-rise are often thought to make the suspension actually really feel firmer and fewer reactive over bumps, resulting in a harsh feeling when braking. The significance of this influence is debatable. 

Nonetheless, anti-rise moreover helps the rear suspension sit deeper into its journey, so it’s disputable whether or not or not extreme anti-rise values result in form of traction beneath braking. 

Much like anti-squat, the amount of anti-rise is a trade-off between preserving the bike’s geometry and the suspension sensitivity. No bike is completely unbiased of braking forces and it’s debatable whether or not or not these braking forces are basically a nasty issue.

Axle path outlined

The axle path is principally the street the rear axle takes as a result of the suspension strikes, measured relative to the mainframe. The course of the axle path at any degree throughout the journey is at correct angles to the swingarm line, which connects the axle to the second centre, by means of the centre of curvature.

As a result of this reality, you can take into account anti-squat purely relating to axle path – the additional the axle path strikes away from the underside bracket, the additional anti-squat. That may be very rather a lot the an identical as saying a greater immediate centre results in additional anti-squat, as described above.

A additional rearward axle path might help a motorbike to absorb certain bump forces for causes unrelated to the chain. Nonetheless for a lot of bikes, the axle path solely strikes rearwards by a few millimetres at most.

As quickly as as soon as extra, high-pivot bikes are a notable exception. Their axle path strikes significantly rearwards all by means of the journey.

It makes intuitive sense {{that a}} rearward path permits the wheel to maneuver out of the way in which wherein additional merely when confronted with huge bumps. The facility produced by these is rearward along with upward (the ability vector components throughout the course at correct angles to the aim on the wheel the place it contacts the bump).

As a result of this reality, it stands to function {{that a}} additional rearward axle path is perhaps larger able to soak up these huge bumps, because of the axle strikes in a course that’s larger aligned with the bump energy.

For an analogy, it’s useful to contemplate suspension forks with fully completely different head angles. The highest angle defines the axle path of the doorway wheel. Slacker head angles, and because of this reality forks, generally tend to absorb kerb-sized bumps additional simply nevertheless are additional susceptible to flex and binding when pushing vertically downwards throughout the car park or when landing to flat.

The an identical issue is happening with a high-pivot bike – huge bumps push the axle throughout the course it wishes to go. The flex and binding scenario doesn’t apply to the rear suspension because of they use a linkage pretty than telescoping through bushings.

Take into account it one different technique. A rearwards axle path means the rear wheel travels backwards relative to the mainframe as a result of the suspension compresses. This means the wheel strikes additional slowly relative to the bump and so strikes up and over it additional slowly too.

Having talked about that, one look at demonstrated a full suspension bike required 30–60 per cent a lot much less power than a hardtail to journey over simulated robust terrain in a lab.

So, if high-pivot suspension absorbs bumps additional efficiently, it stands to function that these bumps will rob the bike of a lot much less forward momentum, nevertheless that’s largely unproven.

Each technique, for bikes with out an idler pulley, that’s all fairly instructional. In that case, the potential bump-absorption advantage of a (barely) additional rearward axle path is negated by the rise in chain improvement and anti-rise they produce. 

Leverage curves vs spring curves

Arguably a really highly effective side of suspension kinematics, relating to journey actually really feel, is the leverage curve – the way in which wherein the leverage ratio changes through the journey.

The leverage ratio is the ratio between the area the rear wheel strikes and the area the shock strikes as a result of the suspension cycles.

The everyday leverage ratio is because of this reality the ratio of rear-wheel journey to the stroke of the shock. Bikes with bigger frequent leverage ratios (fast stroke shocks for the journey) may have a bonus relating to sensitivity because of there’s additional leverage to beat the friction throughout the shock.

Nonetheless, extreme leverage ratios demand bigger spring pressures and higher forces throughout the damper. There’s moreover often a lot much less oil contained within the damper to deal with heat on prolonged runs. Due to this, bikes with lower frequent leverage ratios (longer stroke shocks for a given journey) are sometimes additional reliable and further fixed.

An essential side of the leverage curve is not going to be the frequent ratio nevertheless how the leverage ratio changes all by means of the journey. The higher the ratio, the higher it is to compress the shock, so bikes that start with a extreme leverage ratio and end with a lower one result in a progressive suspension movement, meaning it’s extra sturdy to entry the final word part of the bike’s journey.

It’s counter-intuitive, nevertheless for a motorbike to be progressive the leverage graph slopes downwards as you bear the journey.  

By evaluating the leverage ratio at sag with the leverage ratio at bottom-out, the physique progressivity might be calculated as a share. 

Whether or not or not you have gotten a coil shock or air shock may even have an effect on leverage and spring curves.

With a coil shock (which has a seamless spring payment), the amount of progressivity is printed by the leverage curve alone. With an air shock, the end-stroke progressivity might be fine-tuned (to some extent) with amount spacers. Reducing the spring amount with amount spacers creates additional improvement.

The final firmness of the suspension on the wheel known as the wheel payment. This is usually a function of the shock’s spring payment and the leverage curve – every of which might vary all by means of the journey. A leverage ratio that decreases within the course of the tip of the stroke has an identical influence on the wheel payment as a spring payment that can improve within the course of the tip of its stroke. Every result in a progressive suspension movement.  

A linear leverage ratio with a progressive shock may current an identical wheel payment (whole progressivity) to a progressive leverage ratio with a linear shock. Nonetheless these two setups will nonetheless provide fully completely different traits.

For starters, turning into a very progressive air shock (full of amount spacers) to a motorbike with a linear or regressive leverage curve will result in a faster end-stroke rebound because of extreme spring energy deep throughout the journey.

A progressive leverage curve moreover generates additional resistance from the damper within the course of the tip of the stroke, so every spring and damping forces are used to face up to bottom-out. Whereas, throughout the case of a linear leverage curve, solely the spring energy ramps up within the course of the tip of the stroke.

The share progressivity doesn’t inform the whole story – what points most is the place throughout the journey the physique is progressive. In several phrases, the type of the leverage curve.

As an illustration, bikes with a ‘hanging’ leverage curve have a extreme leverage ratio firstly of the journey to soften the preliminary stroke and drop quickly to a lower ratio in the midst of the stroke in order so as to add assist after sag. That’s considerably associated when using an air shock because of they’re sometimes firmer at first stroke and softer throughout the mid-stroke, relative to a coil.

The opposite case is a sort of humped kind, the place the utmost leverage occurs in the midst of the stroke. As you might depend on, this results in a firmer beginning stroke and a softer mid-stroke than the “hanging” curve.

Blended with an air shock, this lack of mid-stroke assist can result in a wallowing actually really feel in compressions, along with elevated pedal-bob – it’s not solely anti-squat that impacts pedal effectivity.

The leverage curve must be progressive within the course of the tip of the stroke, nevertheless this is not the place the assistance is required with an air shock. Bikes with this type of leverage curve might match larger with a coil spring. Bikes that lack assist throughout the mid-stroke are inclined to require bigger ranges of compression damping to face up to mid-stroke wallowing, nevertheless this negatively impacts sensitivity all by means of the stroke.

How progressive your bike should be is completely personal – it relies upon upon the rider’s energy, terrain and utilizing style.

As a result of stylish air shocks, progressivity is properly tunable by the tip shopper, nevertheless a motorbike’s leverage curve nonetheless performs an unlimited place in the way in which it feels, considerably throughout the mid-stroke, and that’s one factor that will’t on a regular basis be remedied with shock setup.

Should I choose a motorbike based mostly totally on its suspension design?

Whereas suspension design is crucial to consider when deciding on a mountain bike, it shouldn’t be the deciding problem.

It’s best to first have an considered how rather a lot suspension journey you need for the paths you may be utilizing, along with an considered the sizing and geometry required. 

Whether or not or not single-pivot, Horst or twin-link, it’s the details of pivot placement that make all the distinction. 

Bikes with the an identical major format sometimes present very fully completely different kinematics and journey actually really feel, because of this reality it might be foolish to say one design performs larger than each different.

Single-pivot suspension affords straightforward reliability nevertheless provides designers little administration over the bike’s kinematics. 

Together with linkages makes it attainable to control the physique’s leverage curve and progressivity, whereas Horst or twin-link layouts can improve administration over the pedalling and braking behaviour too, significantly if the hyperlinks counter-rotate.

Nonetheless is {that a} bonus? It depends upon completely on what the designers do with that administration because of it’s not on a regular basis for the most effective.

Whereas the rear shock setup stays a really highly effective side of rear suspension effectivity, a superb shock tune obtained’t make up for a flawed suspension design. 

That’s considerably true if a physique has excessive chain improvement or a leverage curve that’s not supportive ample for the rider’s desires. In that case, the shock setup is perhaps at biggest a sticking plaster for poor design.

Ultimately, the suspension traits that work biggest for you may rely upon the way in which you journey. As an illustration, one criticism levelled at true single-pivot bikes is that they’re often pretty linear, nevertheless which can go properly with some riders preferring an opulent actually really feel.

Equally, people who want to hammer down robust terrain couldn’t like a motorbike with an extreme quantity of pedal-kickback, whereas some might similar to the pedal-efficient and interactive actually really feel that comes with extreme ranges of anti-squat. 

It’s largely a matter of fashion and that most likely explains why we nonetheless see such an unlimited array of designs within the market.