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March 30, 2018 0 Comments

How to Set Up Your Motorcycle's Suspension

Understanding motorcycle suspension is important if you wish to get the most out of your riding experience. To ensure your bike is stable and each ride is comfortable, it is crucial to know how to adjust motorcycle suspension to your weight and height. After all, bikes are manufactured to specified designs, but no bike will be pre-adjusted to you as an individual.

Before You Start Making Changes

In the course of a single day, you can learn a lot of things about setting up motorcycle suspension and setting sag on front forks. Understanding how different adjustments to your suspension setup affect your ride will allow you to make the right changes.

Before you begin making changes to your bike there are a few key things that you will want to check. Inspect the shock, fork, tire tread/pressure, steering-head bearings, chain tension and various other parts of the bike to ensure they are in optimal working condition.

As you proceed to make adjustments, keep a record of your current settings and the changes you make in a notebook or on your phone. This way you can easily go back to what you had before if necessary.

Know What Does What: Motorcycle Suspension Settings Explained

Before you proceed with bike maintenance or suspension adjustments, read the manual that came with your bike to learn all you need to know about your particular make and model. That said, there are some standards that apply to bikes in general. For example, various parts and functions play key roles in the stability of bikes. When you learn to identify these parts and functions, you can perform maintenance on just about any bike.

Preload

The preload adjuster affects the shock or fork spring by either shortening or extending the spring. While many think that you can compensate a too soft or too stiff spring, this is a common misconception. While this can help if the spring is excessively soft or stiff, the best option is to change out the spring for a new one.

Preload allows you to change the shock setting if necessary. When you increase the preload, the bike will rise on its suspension. When you decrease the preload, it will bring the bike closer to the bottom of its suspension travel, lower to the ground.

The preload for the front of the bike is at the top of the fork-tube, which contains a large and small nut. The large nut is the preload adjuster, and the small nut is the rebound adjuster. When you slide the fork tubes higher or lower, the change will alter the front ride height and the center of gravity.

To change the rear preload, adjust the collar on top of the spring by turning it. On certain bikes, the addition of a shim to the underside of the upper clevis will allow you to alter the ride height at the rear.

Compression Damping

Compression damping is the function of suspension that allows a bike to absorb the impact of bumps along a road. The compression damping determines the “softness” or “stiffness” of a bike. When you ride over a speed bump, compression damping will determine the speed at which the suspension will compress.

Compression damping

If the compression damping is stiff, the shock will be unable to compress sufficiently in response to the impact of the bump. Consequently, the chassis – and you – will bear the impact of the wheel's movement as your bike rises on the bump.

If the compression damping is insufficient – too soft – the suspension will be compressed too much by the bike's weight transfer as you ride over bumps. Front compression can be dampened with adjustments to the fork at the bottom. The adjuster to the rear compression damping is typically located on the head of the shock.

Rebound Damping

Rebound damping is the function of suspension that helps a bike resume its proper position after riding over a bump. The function determines the ability of the bike's suspension to extend itself when necessary. When your bike rides over a bump, the rebound suspension is what keeps the tires in contact with the ground.

If the rebound damping is excessive, the suspension will compress when your bike hits a bump, causing the bike to rise above the ground. The rebound damping needs to be adjusted to where it will extend the suspension, which will keep the bike in contact with the ground as you drive over bumps.

With too little rebound damping, the suspension will extend faster than it should when you hit the bump, raising the bike. Due to the role damping plays in the contact of your tires with the ground, proper grounding is crucial to your safety as a rider. Rebound damping can be adjusted at the bottom of the shock.

Trail

The trail is an imaginary line that extends between the bottom of the front tire to the contact patch. This line helps measure the potential steering functionality of the bike. The purpose of making trail measurements is to get the proper steering balance. If there is not enough trail, the bike will steer faster, but at the expense of the bike's stability. If there is too much trail, the bike will be more stable, yet hard on the steering.

There are two ways to alter the trail. The first involves changing the size of the front tire to something with more or less diameter. Adjustments to the ride height will also alter the trail.

Ride Height

The height of your bike's frame and subframe are critical to the overall performance of the bike. Ride height is the height between the ground and the bike's steering head and subframe. If the height balance gets tipped to any degree between the front and rear, it will alter the trail. Specifically, less height in front will reduce rake and make the bike steer faster. This would also compromise the stability of the bike.

Bike frame height

If you heighten the bike in front and bring down the back, the trail will lengthen and make the bike more stable. However, this will also slow the steering down.

To adjust the ride height setting at the rear, turn the adjustable clevis under the shock absorber. If the shock has a locking nut, unfasten that first and then make the adjustment. Be sure to relock the shock once you are done. To change the ride height in front, adjust the triple-clamp forks.

Setting Up Your Bike’s Suspension for You

Now that you understand all the components of your bike’s suspension, it’s time to start making adjustments.

Step 1: Preload

Sag is the amount of suspension a bike has when a rider is on board. To alter the sag, you must change the degree to which the springs in the rear shocks and forks are compressed. The purpose is to bring the sag to a level that works with your weight as a rider, which will make the bike ride more smoothly and provide more stability.

First, you will want to set your preload for static sag. Static sag is how much your bike’s suspension settles with you on it.

  1. Get some buddies to help you fully extend your front suspension so that you can measure the distance between the bottom triple clamp (conventional) or the fork bottom (inverted) and the fork seal, and mark this down as distance A.
  2. Set the bike upright and have a friend hold the back of the bike while you climb on and put both feet on the pegs. Have another friend push down on the front end and take another measurement like before after the bike has had a moment to settle – this will be measurement B.
  3. Have your friend then lift up the front end and then take another measurement after allowing it to settle – this will be measurement C.
  4. Calculate your static sag by using this equation: A-(C+B)/2

This equation helps you to take into account any stiction. You want to shoot for the following sag measurements:

  • 25mm for track riding
  • 30mm for street riding

Recommended sag for street and track riding

To adjust your sag, you can loosen or tighten your front preload. Tighten up the preload if you have too much sag or loosen the preload if you have too little.

Step 2: Damping

No measurements are involved when it comes to determining the points at which the compression and rebound damping begin and end. Consequently, the process can be subjective. In any case, before you make any adjustments to the damping, write down the current settings so that you can track your changes.

Turn the compression adjusters to the softest setting. As you do this, count the number of clicks you hear. Alternately, count the number of turns it takes before the adjuster stops. Be careful not to turn the adjusters too tight, as this might damage some of the internal mechanisms. Turn each adjuster halfway back from its full range. If the adjuster rotates for 18 clicks in total, turn it back to the ninth click.

To get the proper rebound setting, you need to be able to feel things out. See how the front end of the clamp rises as you push down on it. Once you release the pressure, the clamp should only take a second to resume its regular position.

Turn the rebound adjusters until they reach the stiff position and apply pressure to the suspension. Release the pressure and see how long it takes for the suspension to return to normal — it should be a lot slower.

Let them all the way out and repeat the process. This time, the shock should extend much differently. Possibly, it will top the suspension and then retract, similar to an automobile with blown shocks. Apply and release manual pressure to the rear section and watch how long it takes to resume position. It shouldn't take more than a second.

Adjust the rebound to a setting that makes it return to its original resting point each time you apply and release manual pressure. If the bike rises too fast at the front or rear, increase the rebound. If the bike takes longer than a second to resume position, decrease the rebound.

Step 3: Go for a Ride to Test It Out

Once you've made notes of all your new adjustments, take the bike out for a ride. Perform the test ride in an area where there is no traffic, such as a quiet back road or a racing track. The idea here is to concentrate on the performance of the vehicle over the course of several laps. Does it perform the way you expected?

You want to make sure the bike is neither too stiff or too soft as it reacts to the turbulence you encounter, such as gravel, on-ramps and speed bumps. If your bike bears too much impact as your tires encounter these momentary inclines, your settings will need more adjustments.

Step 4: Making Angle Adjustments — Height and Preload Adjustments

Now that you have the initial suspension adjustments made, you can experiment with sharpening or slowing your steering by changing the angle of the bike’s chassis.

Most bike’s will have limited adjustment capabilities in the rear end, but you may be able to use a shim under the shock’s clevis depending on the bike, switch out the rear shock for one with a length adjuster or switch out your dog bones for a pair of adjustable arms. At the front of the bike, you can raise or lower your front fork tubes in the triple clamps.

You can use a front preload adjustment to raise or lower your bike’s front end, since a preload essentially only moves a suspension’s working range up or down as you make adjustments. This can give you the chance to test different ride heights to get a feel for the effects they have on the riding experience.

You can use a front preload adjustment to raise or lower your bike’s front end, since a preload essentially only moves a suspension’s working range up or down as you make adjustments. This can give you the chance to test different ride heights to get a feel for the effects they have on the riding experience.

Each time you make an adjustment to the preload in one direction or the other, take the bike on a test lap around a track or along a back road to get a feel for the performance. Providing the bike neither tops or bottoms out, any change to the riding feel is likely the result of differences in trail that came about through the preload alterations and not any change in the stiffness of the fork.

Set the preload a few turns in the other direction – no more than three or four turns at a time – then give the bike another spin around the track. Pay attention to the difference in the bike's performance. When you find a setting that feels most comfortable and secure, adjust the preload further in that direction. If there is no further leeway to make adjustments — or any further changes will cause the bike to top or bottom out — alter the height of the fork tube and bring the preload back to its central range.

You can lower the tubes in the triple clamp by approximately 1mm for every turn that you backed the adjuster out and raise them the same amount for every turn you had to tighten it in.

Additional Tips for Setting Up Your Bike’s Suspension

Here are a few extra tips to keep in mind as you work on your bike’s suspension:

  • Take Constant Notes: Keeping a notebook in your garage, or wherever you store and work on your bike, is a great way to make sure that you always have it on hand to review past suspension adjustments and make note of any new ones as you look to improve your ride. Future you will thank you!
  • Put Your Gear On: Make sure that any measurements that you take with you on the bike include your gear. The weight of you plus your helmet, jacket, pants, riding boots and any other gear is going to be several pounds different than you in a pair of shorts, a t-shirt and the sandals that you wear around the garage.
  • Get a Few Friends to Help: You can try to take the measurements on your own, but the fact is that the process is nearly impossible to do all by yourself. Steal a couple of friends for the day to help you take all the measurements that you need so that you have a good starting baseline, and accurate measurements as you continue to make adjustments.

Test out different suspension settings

Ducati & MV Agusta Aftermarket Suspension Parts from Design Corse

As you learn more about your motorcycle suspension setup, test out different adjustments over time and take notes of each one. Also, try aftermarket suspension modifications when your motorcycle needs changes beyond the limitations of its current setup.

Design Corse is the leading online store for aftermarket performance parts for Ducati and MV Agusta motorcycles, offering parts from the industry's leading brands, including R&G Racing, Oberon Performance and QD Exhaust. To learn more about our inventory of aftermarket suspension parts, browse our online store today.



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