Harley-Davidson Rear Shock Absorbers Buyer’s Guide: Choosing the Right Suspension for Your Bike

Changing the rear shock absorbers on a Harley-Davidson can make a surprisingly large difference to the motorcycle.

The obvious reason for replacing them is usually comfort. A bike that crashes over bumps, wallows through bends or feels harsh on poor roads may benefit from better rear suspension.

But there is more to choosing shock absorbers than buying an expensive pair and bolting them on.

Shock length, spring rate, preload, damping, suspension travel and the weight the motorcycle regularly carries all matter. Changing the length can also alter ride height, steering geometry and ground clearance.

And on some Harley-Davidson model families, what appears to be a conventional shock absorber arrangement is nothing of the sort.

Quick answer: Choose rear shock absorbers according to your exact Harley-Davidson model and year, rider weight, passenger and luggage use, desired ride height and the type of riding you do. Do not choose purely by shock length or appearance. Correct spring rate and damping are at least as important.

Here is what we would consider before buying.

What Do Rear Shock Absorbers Actually Do?

The rear suspension has two main jobs.

The spring supports the motorcycle and allows the rear wheel to move when it encounters bumps.

The damper controls that movement.

Without a spring, the motorcycle would simply collapse onto the suspension stops.

Without sufficient damping, the spring would continue bouncing after every disturbance.

A good suspension unit therefore needs to support the motorcycle at the correct ride height while allowing controlled movement of the wheel.

That sounds straightforward.

In practice, the shock absorber has to deal with a motorcycle that may be ridden solo one day, carrying a passenger and luggage the next, on smooth roads, broken roads and everything in between.

That is why set-up matters.

Why Replace the Standard Rear Shocks?

There are several common reasons.

• Improving ride comfort
• Improving control on poor road surfaces
• Reducing wallowing in bends
• Increasing suspension travel
• Improving support when carrying a passenger
• Improving support with luggage
• Raising the rear of the motorcycle
• Lowering the motorcycle
• Increasing ground clearance
• Adding adjustable damping
• Replacing worn original units

Not everybody needs aftermarket suspension.

If the standard shocks suit your weight, riding style and typical use, replacing them simply because aftermarket parts exist may achieve very little.

The useful question is not:

“What are the best Harley shocks?”

It is:

“What am I trying to improve?”

Signs Your Rear Shocks May Be Worn

Suspension deteriorates gradually, so riders can become accustomed to poor performance without noticing how much it has changed.

Possible symptoms include:

• Excessive bouncing after bumps
• A harsh ride despite reasonable tyre pressures
• Rear suspension bottoming out
• Wallowing or instability through bends
• Excessive pitching during acceleration and braking
• Poor control on uneven roads
• Oil leaking from the shock absorber
• Damaged bushes or mountings
• Corrosion on the damper shaft
• A noticeable difference between the two units on a twin-shock motorcycle

Some symptoms can also be caused by tyres, tyre pressures, wheel bearings, swingarm bearings or other chassis components.

Do not automatically blame the shock absorbers without checking the rest of the motorcycle.

Harley-Davidson Rear Suspension Types

Before comparing shock absorbers, identify what type of suspension the motorcycle actually has.

Harley-Davidson has used several different arrangements.

Twin External Shock Absorbers

Many Sportster, Dyna and Touring models use two externally visible shock absorbers, one on each side of the motorcycle.

This is probably the most familiar arrangement.

Although the units look relatively simple, replacements still need the correct:

• Length
• Mounting type
• Bush dimensions
• Spring specification
• Clearance
• Load capacity

A shock absorber that physically bolts into place is not necessarily correctly specified for the motorcycle.

Traditional Softail Suspension

Earlier Softail models use a very different arrangement.

Rather than two conventional upright rear shocks beside the wheel, the suspension units are concealed beneath the motorcycle.

The system was designed to give the appearance of a rigid rear frame while retaining suspension movement.

Because the geometry and method of operation differ from a conventional twin-shock arrangement, Softail shock absorbers must be specifically designed for the relevant application.

Do not try to compare their quoted dimensions directly with the external shocks used on a Dyna, Sportster or Touring model.

2018-On Softail Suspension

The later Softail chassis introduced for the 2018 model year uses a single centrally mounted rear shock absorber.

This system is entirely different from the concealed twin-shock arrangement on previous Softails.

Again, the fact that both motorcycles are called Softail does not make their suspension components interchangeable.

Year and model matter.

Shock Length

On conventional twin-shock motorcycles, one of the first measurements people look at is shock length.

It is commonly measured from the centre of one mounting eye to the centre of the other.

A relatively small difference can noticeably alter the motorcycle.

However, shock length is not the same thing as suspension travel.

Two shock absorbers can have the same overall length but different stroke, internal design, spring characteristics and damping.

That is why buying purely by an eye-to-eye measurement is risky.

What Happens if I Fit Longer Rear Shocks?

Longer shocks generally raise the rear of a conventional twin-shock motorcycle.

Potential effects can include:

• Increased rear ride height
• Increased ground clearance
• Increased cornering clearance
• Quicker steering response
• A different seat height
• Changed chassis attitude
• Different drive belt or chain geometry

Some riders deliberately raise Dynas and Sportsters to increase cornering clearance and improve the way the motorcycle turns.

That does not mean fitting the longest shock that will physically go on the bike is a good idea.

Clearance at full suspension extension and compression must still be checked.

What Happens if I Fit Shorter Rear Shocks?

Shorter shocks generally lower the rear of a conventional twin-shock motorcycle.

This is popular with riders who want:

• A lower seat height
• Easier reach to the ground
• A lower stance
• A particular custom appearance

There are compromises.

Reducing ride height can reduce available suspension travel and ground clearance.

It can also reduce cornering clearance and increase the likelihood of footrests, exhaust components or other parts touching the road.

Lower is not automatically better.

Is Lowering a Harley-Davidson Bad for the Ride?

It can be if the reduction in height is achieved at the expense of useful suspension movement.

A shock absorber has a finite amount of travel.

If the motorcycle sits lower and there is less usable movement remaining before the suspension reaches its limit, it may bottom out more easily.

A properly engineered lowering shock can work perfectly well within its intended use, but physics does not disappear because the motorcycle looks better.

The less suspension travel you have, the less distance the suspension has available to absorb a bump.

Ground Clearance Matters

Harley-Davidson motorcycles already vary significantly in cornering clearance.

Lowering the rear can reduce it further.

This may not matter much to somebody riding gently on relatively straight roads.

It may matter considerably to somebody who regularly rides quickly on twisting roads.

Before lowering a motorcycle, consider what is underneath it.

Exhausts, footboards, footrests, stands and frame components may all reach the road sooner.

Spring Rate

The spring has to support the combined load carried by the suspension.

That includes more than the rider.

It can include:

• Rider
• Passenger
• Luggage
• Panniers
• Tour-Pak
• Accessories
• Additional equipment

A spring that works perfectly for a 70 kg solo rider may be unsuitable for a heavily loaded Touring model carrying two people and luggage.

This is one reason buying suspension simply by motorcycle model can sometimes be incomplete.

The motorcycle matters, but so does the load.

What Happens if the Spring Is Too Soft?

A spring that is too soft may cause:

• Excessive suspension sag
• Frequent bottoming
• Poor support during acceleration
• Reduced ground clearance
• Excessive movement when carrying a passenger
• A vague or wallowing feel

Increasing preload can help within limits, but preload cannot turn an unsuitable spring into the correct spring.

If the spring rate is fundamentally wrong, the proper solution is usually a more suitable spring.

What Happens if the Spring Is Too Stiff?

An excessively stiff spring can create the opposite problem.

Possible symptoms include:

• Harsh ride quality
• Limited suspension movement
• Poor compliance over small bumps
• Reduced grip on uneven surfaces
• The rear of the motorcycle feeling unsettled

Suspension needs to move.

Making everything as stiff as possible does not automatically improve handling.

Straight-Rate and Progressive-Rate Springs

A straight-rate spring increases in force at a broadly consistent rate as it compresses.

A progressive-rate spring becomes increasingly resistant as it compresses.

Both approaches can work well.

Progressive springs can provide relatively compliant initial movement while increasing resistance deeper into the suspension travel.

Straight-rate springs can provide very predictable behaviour and are widely used in performance applications.

The design of the complete shock absorber matters more than simply choosing one spring type because somebody on the internet says it is better.

What Is Preload?

Preload changes the amount of initial compression applied to the spring.

It is primarily used to set the motorcycle's operating ride height for the load being carried.

If you add a passenger and luggage, additional preload may be needed to compensate for the extra weight.

Preload does not make the spring itself fundamentally stiffer.

That distinction is important.

Turning the preload adjuster fully in because the spring is too soft is not the same as fitting the correct spring rate.

Setting Suspension Sag

Sag is the amount the suspension compresses from fully extended when the motorcycle is carrying its normal load.

Measuring sag helps establish whether the motorcycle is sitting within the intended portion of its suspension travel.

Ideally, measure with the rider aboard in normal riding equipment.

If the bike is regularly used two-up, it is worth checking the loaded condition as well.

The correct target varies according to motorcycle, suspension design and manufacturer, so use the suspension manufacturer's recommended figures rather than relying on one universal number.

What Is Damping?

The spring determines how the suspension supports the motorcycle.

Damping determines how quickly it moves.

There are two main directions of suspension movement.

Compression

Compression occurs when the shock absorber shortens.

For example, when the wheel hits a bump.

Compression damping controls how quickly that movement occurs.

Rebound

Rebound occurs when the suspension extends again after being compressed.

Rebound damping controls how quickly the spring is allowed to push the wheel back towards its normal position.

Both are important.

Too Little Rebound Damping

If rebound damping is insufficient, the rear suspension can extend too quickly after a bump.

The motorcycle may feel bouncy or poorly controlled.

Several bumps in succession can make the back of the bike feel particularly unsettled.

Too Much Rebound Damping

Too much rebound damping can prevent the suspension extending quickly enough between bumps.

The shock can effectively remain partially compressed as successive bumps arrive.

This can make the ride harsh and reduce available suspension movement.

More damping is not automatically better.

Adjustable Rebound Damping

Many aftermarket shock absorbers allow the rider to alter rebound damping.

This can be particularly useful when the motorcycle's use varies.

A rider may want a different setting when touring with luggage and a passenger compared with riding solo.

However, adjustment is only useful if you use it sensibly.

Turning every adjuster fully clockwise is not a suspension set-up.

Start with the manufacturer's recommended setting and make small changes.

Adjustable Compression Damping

More sophisticated shock absorbers may also provide compression adjustment.

Some systems separate high-speed and low-speed compression damping.

Those terms refer primarily to the speed at which the suspension is moving, not simply the road speed of the motorcycle.

For most road riders, correctly selected springs and well-calibrated damping are more important than having the maximum possible number of adjusters.

Do I Need Fully Adjustable Shocks?

Not necessarily.

A high-quality shock absorber with the correct spring and well-developed fixed damping may work extremely well.

Adjustment becomes valuable when:

• Rider weight differs significantly from average
• The motorcycle carries widely varying loads
• The rider wants to fine-tune handling
• The motorcycle is ridden particularly hard
• Different road conditions require different set-ups

Buying a shock because it has numerous adjusters is pointless if none of them are ever set correctly.

Emulsion Shock Absorbers

In an emulsion shock absorber, the oil and pressurised gas occupy the same main chamber rather than being completely separated by an external reservoir.

This can provide a compact, effective design suitable for many road motorcycles.

Not having an external reservoir does not automatically make a shock poor quality.

Again, it depends on the complete design.

Reservoir Shock Absorbers

Some higher-performance rear shocks use piggyback or remote reservoirs.

The additional reservoir can provide greater oil volume and help control temperature during sustained hard use.

It can also allow more sophisticated damping arrangements.

This can be useful on heavily loaded Touring motorcycles or performance-orientated builds.

For a rider covering moderate road mileage, however, a reservoir is not automatically essential.

Piggyback Versus Remote Reservoirs

A piggyback reservoir is attached directly to the main shock body.

A remote reservoir is connected by a hose and mounted elsewhere on the motorcycle.

Which arrangement is suitable depends partly on the available space around the motorcycle.

Exhaust systems, panniers, belt guards and other accessories can all affect clearance.

Passenger and Luggage Use

This is one of the most important questions when choosing suspension.

A motorcycle used exclusively by one rider has a relatively consistent load.

A Touring model may carry:

• Rider
• Passenger
• Full panniers
• Tour-Pak
• Additional luggage

That is a very different suspension requirement.

If two-up touring is a regular part of the motorcycle's life, say so when choosing shock absorbers.

Do not select suspension solely around the solo condition and then expect it to behave identically when heavily loaded.

Remote Preload Adjusters

Some shock absorbers use a remote hydraulic preload adjuster.

These can be particularly convenient on Touring motorcycles.

Rather than using tools or a stepped collar whenever a passenger climbs aboard, preload can be adjusted more easily.

If your motorcycle regularly changes between solo and fully loaded use, this can be genuinely useful rather than merely decorative.

Ride Comfort Versus Handling

People often talk about comfort suspension and performance suspension as though they are opposites.

They are not necessarily.

Poorly controlled suspension can be both uncomfortable and bad for handling.

A properly specified shock can improve control while also allowing the wheel to follow the road more effectively.

The goal is not simply to make the suspension soft.

It is to make it controlled.

Why Very Stiff Suspension Can Reduce Grip

The tyre needs to remain in contact with the road.

If the suspension is too stiff to follow uneven surfaces, the wheel can skip across bumps rather than moving with them.

A motorcycle that feels extremely firm is not automatically better controlled.

Good suspension allows movement, but controls it.

Rear Shocks and Front Suspension Should Work Together

Changing only the rear suspension can alter the balance of the motorcycle.

If the front forks are very soft and poorly damped while the rear is substantially upgraded, the difference may become more noticeable.

You do not necessarily need to replace everything at once.

But think of the motorcycle as a complete chassis.

Front and rear suspension are working on the same bike.

Raising the Rear and Steering Response

On many conventional motorcycles, raising the rear changes the chassis attitude and can make steering feel quicker.

This is one reason longer shocks are popular on some performance-style Harley-Davidson builds.

There are limits.

Changing ride height also alters other relationships within the chassis.

Do not assume that more rear height will continue making the bike better indefinitely.

Lowering the Rear and Steering Response

Lowering can make the steering feel slower and may increase stability in a straight line, depending on the amount changed and the rest of the geometry.

It also reduces ground clearance.

Again, these are changes to the motorcycle's chassis, not simply cosmetic alterations.

Drive Belt Clearance and Adjustment

If the motorcycle uses belt final drive, significant changes to suspension height can affect the relationship between the rear axle, swingarm and transmission pulley.

Check belt adjustment according to the correct procedure for the motorcycle.

Also check clearance around:

• Belt guard
• Rear tyre
• Fender
• Exhaust
• Brake hose
• Wiring
• Other nearby components

Do this throughout the suspension's range of movement where practical.

Rear Tyre and Fender Clearance

A lowered motorcycle can appear to have plenty of tyre clearance while stationary.

That does not tell you what happens when the suspension compresses fully.

The tyre must not contact the fender, wiring, fasteners or other components during suspension movement.

This becomes particularly important when changing shock length, tyre size or both.

Exhaust Clearance

Aftermarket exhaust systems can occupy space close to the rear suspension.

Piggyback reservoirs and larger-diameter springs may require more clearance than the original shocks.

Check both sides of the motorcycle carefully.

Do not assume that a shock listed for the bike will automatically clear every aftermarket exhaust ever produced.

Pannier Clearance

Touring models may have panniers close to the shock absorbers.

Remote reservoirs, piggyback units and preload adjusters need sufficient space.

This is another reason application-specific kits are preferable to trying to adapt a universal unit.

Are Expensive Shocks Worth It?

Sometimes.

A premium shock absorber may offer:

• Better damping control
• Higher-quality internal components
• More accurate spring options
• Better heat management
• Rebuildability
• Adjustable rebound
• Adjustable compression
• Hydraulic preload
• Greater consistency during demanding use

Whether you need those features depends on how the motorcycle is used.

If the main problem is that your original shocks are worn out and you ride gently for short distances, you may not need competition-level suspension technology.

If you regularly tour two-up, ride quickly on poor roads or want precise control over the chassis, the additional capability may be worthwhile.

Buy the suspension that solves your problem.

Rebuildable Shock Absorbers

Some aftermarket shocks are designed to be serviced and rebuilt.

Oil, seals, bushes and other internal components can be replaced rather than disposing of the entire unit when performance eventually deteriorates.

This can be attractive for riders planning to keep the motorcycle for many years.

Check the manufacturer's servicing arrangements and recommended intervals.

Do Rear Shocks Need Maintenance?

Original equipment units are often treated as replaceable assemblies.

Many premium aftermarket units are serviceable.

Even where no routine internal maintenance is required by the rider, inspect them periodically for:

• Oil leakage
• Damaged shafts
• Worn bushes
• Loose mountings
• Damaged springs
• Corrosion
• Unusual movement or noise

Suspension components live in a fairly hostile part of the motorcycle.

Should Both Rear Shocks Be Replaced Together?

On a twin-shock motorcycle, yes, they should normally be treated as a matched pair.

The two units need to provide consistent springing and damping.

Replacing one worn shock and leaving another old unit in place would create an undesirable imbalance.

Aftermarket twin shocks are therefore normally supplied as a pair.

Can I Mix Different Shock Lengths?

No.

Twin-shock motorcycles need matching units of the same specification on both sides.

This is not an area for improvisation.

Shock Mounting Bolts and Bushes

Do not overlook the mountings.

Shock absorber bushes can wear, and mounting bolts need to be in good condition and tightened to the correct specification.

A high-quality new shock mounted through damaged or loose hardware will not perform as intended.

Check spacers and washers as well.

Installation

Rear shock replacement can appear deceptively straightforward, especially on conventional twin-shock motorcycles.

The motorcycle still needs to be securely supported so the rear suspension is unloaded in a controlled manner.

Follow the motorcycle and shock manufacturer's instructions, use the correct tightening specifications and confirm that all components have adequate clearance.

If there is any doubt about safely supporting the motorcycle or completing the work correctly, have the suspension fitted professionally.

Setting Up New Shocks

Do not assume the factory setting on an adjustable shock will be perfect for every rider.

Start with the manufacturer's baseline recommendation.

1. Set preload for the normal load.
2. Check suspension sag.
3. Ride the motorcycle on familiar roads.
4. Alter only one damping setting at a time.
5. Make small changes.
6. Keep a note of the original setting.
7. Return to the baseline if the changes make things worse.

Random adjustment makes it almost impossible to understand what improved or worsened the motorcycle.

How Do I Know Which Way to Adjust Rebound?

Follow the instructions supplied with the suspension.

In general, the adjuster changes how quickly the shock extends after compression.

If the rear feels too loose and bouncy, additional rebound damping may help.

If the suspension feels as though it cannot recover between bumps, there may be too much.

Small changes are normally more useful than large ones.

Do I Need Different Settings for a Passenger?

Possibly.

The first adjustment is usually preload because the additional weight changes the motorcycle's ride height.

Depending on the suspension design, damping may also need adjustment.

Manufacturers of adjustable shocks often provide suggested settings for solo and two-up riding.

Those are a useful starting point.

Choosing Suspension for a Touring Model

For a motorcycle regularly used for long-distance touring, we would prioritise:

• Correct spring rate
• Good compliance over poor roads
• Consistent damping
• Load capacity
• Easy preload adjustment
• Passenger comfort
• Reliability

A remote hydraulic preload adjuster can be particularly useful if the load changes regularly.

Choosing Suspension for a Performance Build

For a performance-orientated Dyna, Sportster or similar build, priorities may be different.

These could include:

• Increased rear ride height
• Increased cornering clearance
• More controlled damping
• Appropriate spring rate
• Rebound adjustment
• Reservoir shocks where appropriate
• Improved chassis balance

The objective is usually control rather than softness.

Choosing Suspension for a Lowered Custom

If appearance and seat height are the priorities, choose a suspension system specifically designed to provide the required lowering.

Check carefully:

• Remaining suspension travel
• Ground clearance
• Cornering clearance
• Tyre-to-fender clearance
• Belt or chain clearance
• Exhaust clearance
• Side-stand suitability

A motorcycle looking lower in the car park is not much consolation if it bottoms out on the first large bump.

Common Rear Shock-Buying Mistakes

Buying purely by length:
Length does not tell you spring rate, damping, travel or suitability.

Choosing the shortest shock possible:
Lowering comes with compromises in travel and clearance.

Ignoring rider weight:
Suspension supports people, not catalogue averages.

Forgetting the passenger:
Two-up use can dramatically increase the load.

Trying to correct the wrong spring with preload:
Preload adjusts ride height. It does not change the fundamental spring rate.

Assuming stiffer means better handling:
Suspension needs to move.

Ignoring front suspension condition:
Front and rear work together.

Buying by appearance:
Piggyback reservoirs look impressive. That does not mean they are necessary for every motorcycle.

Ignoring accessory clearance:
Panniers, exhausts and belt guards can all matter.

Assuming every Softail uses the same suspension:
Earlier and later Softail chassis use fundamentally different rear suspension arrangements.

Questions We Are Often Asked

What are the best rear shocks for a Harley-Davidson?

There is no single best shock absorber for every Harley-Davidson. The correct choice depends on model, year, rider weight, load, riding style and desired ride height.

Will new rear shocks make my Harley more comfortable?

They can, particularly if the original units are worn or poorly suited to the rider and load. Correct spring rate and damping are crucial.

Can I lower my Harley by fitting shorter shocks?

On motorcycles using conventional twin shocks, shorter units can lower the rear, but suspension travel and ground clearance must be considered.

Will longer shocks make my Harley handle better?

They can alter chassis geometry, improve ground clearance and quicken steering on some models. The result depends on the motorcycle and the amount of change.

Do I need adjustable shocks?

Not necessarily. Correctly specified fixed damping can work extremely well. Adjustment is useful when load and riding conditions vary or when greater control over set-up is wanted.

What does preload do?

Preload adjusts the initial compression of the spring and is primarily used to establish suitable ride height for the load being carried.

Does increasing preload make the spring stiffer?

It does not change the spring's fundamental rate. If the spring itself is unsuitable for the load, additional preload is not a complete solution.

Should I replace both shocks at once?

On a conventional twin-shock motorcycle, the two shocks should normally be replaced as a matched pair.

Are reservoir shocks better?

They can provide advantages during demanding use, including greater oil volume and improved temperature control, but they are not automatically necessary for every rider.

Can I fit shocks from another Harley model if the length is the same?

Do not assume so. Mountings, travel, spring rate, damping, clearance and suspension geometry can differ considerably.

The Hogparts View

Rear suspension is one of the easiest areas of a motorcycle to misunderstand because two shock absorbers can look almost identical while behaving completely differently.

The number printed beside the eye-to-eye length is useful.

It is not enough.

We would start with the motorcycle, rider and intended use.

Is the bike ridden solo?

Does it regularly carry a passenger?

Is it a heavily loaded Touring model?

Are you trying to gain ground clearance on a performance-style Dyna?

Are you trying to make a Softail easier to manage at a standstill?

Or are the original shocks simply worn out?

Once you know the problem you are trying to solve, the correct suspension becomes much easier to identify.

Before You Order: The Hogparts Rear Suspension Checklist

Make sure you know:

• Exact Harley-Davidson model
• Model year
• Current suspension arrangement
• Rider weight
• Passenger use
• Typical luggage load
• Current shock length where relevant
• Desired ride height
• Whether lowering is required
• Whether increased ground clearance is required
• Preload adjustment requirements
• Damping adjustment requirements
• Pannier clearance
• Exhaust clearance
• Belt or chain clearance
• Whether the front suspension is in good condition

That information is considerably more useful than simply asking for a pair of shocks that are “a bit better than standard”.

Final Thoughts

Rear shock absorbers influence comfort, control, ride height and the way the motorcycle responds to the road.

That makes them worth choosing properly.

For most riders, the priorities should be:

Correct application first, correct spring second, suitable ride height third, damping and adjustment according to use, and appearance after that.

A correctly specified, relatively simple shock absorber will usually work better than a highly adjustable unit with the wrong spring or dimensions.

And if you are lowering the motorcycle, remember that the ground has not moved.

Every millimetre you remove from the motorcycle's clearance has to come from somewhere.

Choose the suspension around how you actually ride the bike, not simply how you want it to look while parked.

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Hogparts is an independent UK supplier of aftermarket parts and accessories for Harley-Davidson motorcycles. Hogparts is not affiliated with, endorsed by or authorised by Harley-Davidson Motor Company. Harley-Davidson names and model references are used solely for identification and compatibility purposes.