How to Adjust Your Motorcycle Suspension

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How to Adjust Your Motorcycle Suspension

Many motorcyclists never bother adjusting the suspension on their motorcycle, being content with the factory settings. However, riders who are looking for the best performance from their bike are more likely to adjust their suspension. While adjusting the suspension does not greatly affect the motorcycle's performance, it affects the "feel" and handling of the bike, especially for racing, whether on or off the streets.

Adjusting a motorcycle's suspension can be confusing. One of the difficulties of adjusting the suspension is that there are several ways of going about it, with different "experts" providing contrasting viewpoints on the perfect suspension setting.

Ultimately, the perfect motorcycle suspension setting is what is perfect for that rider. Since each person rides their bike a little bit differently, what is perfect for one person may not be perfect for another. This is very much an experimental science, and thus, it is best to only make one adjustment at a time and see how it affects the bike's ride before making any other adjustments. It is also a good idea to take notes on the adjustments made so that the bike can be returned to previous settings if necessary.

Understanding Motorcycle Suspension Terminology

As with all things technical, motorcycle suspensions have their own terminology. Without understanding this terminology, it is impossible to understand the process. While this list does not cover every possible term used in motorcycle suspensions, it hits the major ones.

Terminology

Description

Fork height

The amount of the fork that is exposed above the top yoke

Compression

The rate of speed at which the suspension moves downward as the wheel moves upward

Loaded sag

The amount of suspension movement when the rider sits on the bike

Preload

The amount of tension on the suspension springs at rest

Rebound

The rate of speed at which the suspension moves upward when recovering from a bump

Ride height

The distance between the rear axle and tailpiece

Sag

The suspension movement when the bike's weight is lifted off the suspension

Suspension travel

The distance the suspension moves up and down

An adjustment to the suspension generally only adjusts the low-speed reaction of the suspension. In most cases, the high-speed reaction cannot be adjusted, but depends on the low-speed adjustments.

Sag Adjustment

Adjusting the suspension sag is both the first step in adjusting a motorcycle suspension and the most common adjustment made. The suspension sag is affected by the weight of the rider, so this is a very individualistic adjustment, which must be made with the actual rider and any other weight that they typically ride with (helmet, leathers, etc.).

To adjust the sag, one must first measure the existing suspension sag. This must be done with the shocks fully extended and unloaded, and with the rider on-board to get the fully loaded sag. The difference between the two is the needed measurement.

It is best to adjust the vehicle sag with the rebound totally eliminated. This requires opening the rebound valve all the way. To find the rebound valve on the bike's shocks, check the owner's manual. For most motorcycles, the front rebound valve is located on the top of the shocks, and the rear is located near the bottom of the shocks. While opening the valve, keep track of the number of clicks so that it can be reset to the same point later. With Showa suspension components, which are commonly used on Honda motorcycles, the adjustment does not click, so the number of turns must be tracked.

Front Sag Adjustment

To measure the front sag, lift the bike's front wheel off the ground so that it is supported by the rear wheel and the kickstand. Measure the distance in millimeters between the bottom of the steering yoke and the end of the shock. Then have the rider sit on the bike, with his or her feet on the pegs. An assistant will need to balance the bike so that the full weight of the rider and motorcycle is on the wheels. Have the rider bounce a couple of times to ensure that the shocks compress to the normal point of being ridden. Measure the distance again.

The difference between the fully unloaded measurement and the fully loaded measurement is the sag. This should be somewhere between 20 mm and 40 mm. The smaller the sag is, the stiffer the suspension is. This is important for racing or any situation where excellent maneuverability is needed. A higher sag provides for a more comfortable ride, but at the cost of high maneuverability. For street riding, 30 mm is considered normal.

The front sag can be adjusted by turning the adjuster with a 17-mm wrench. The adjuster is usually on the top of the shock, around the rebound valve. Check the owner's manual to be sure. Tightening the adjuster lowers the sag, and loosening it increases the sag.

Adjusting Rear Suspension Sag

The rear suspension sag is measured in the same manner as the front suspension sag. An unloaded and loaded measurement is needed. To get the unloaded measurement, the shock absorber must be at full extension, which can only happen with all weight off the rear wheel. Support the motorcycle on the front wheel and stand. Taking the loaded measurement requires the rider to be mounted, with any additional weight that they normally have when riding.

Once again, the difference between loaded and unloaded sag should be between 20 mm and 40 mm, with 30 mm being normal for street riding.

To adjust the rear sag, the lock nut on the shock needs to be loosened. This is best done with a hammer and drift pin punch. Place the punch on one of the tabs sticking out from the lock nut and give it a sharp hit. One hit should be enough to break it loose. The shock sag itself is made by using a spanner wrench on the shock.

Finalizing Suspension Sag Adjustment

Once front and rear sag adjustments are made, they should be rechecked in the same way they were originally checked. Finalize the adjustment by tightening the lock nut on the rear shock. It can be seated by using the drift pin punch and hammer, turning the nut in the opposite direction.

The rebound valves for both the front and rear shocks should then be reset to the same number of clicks or turns they were set at before making the sag adjustment.

Adjusting Suspension Damping

Suspension damping deals with the compression of the shocks themselves. If not properly adjusted, the suspension can feel like a car that has bad shocks. Ideally, the damping should allow the shock to rebound to the start point after compression, without going over.

To adjust the suspension damping requires adjusting the rebound valves. This is a somewhat subjective adjustment, as there is nothing to measure; rather, it is made based on the action of the shock in test circumstances.

To start, determine the range of adjustment for the rebound valve. This is done by tightening it all the way, counting the number of clicks it takes to reach full tightness. Do not apply any pressure once fully tightened, as this can cause damage to components within the shock absorber. Write down the number of clicks so that it is possible to return the shock to the original setting. Then turn the shock to the fully open position, counting the number of clicks. This is the full range of the suspension damping adjustment. Divide this number by two to find the midpoint, and adjust the dampening valve to that point.

Forcibly press down on the suspension as far as possible and allow it to spring back up. If it overshoots the "neutral" point, the rebound is too low; tighten the valve a bit more. If it takes more than a second to return to the neutral point, it is too high; loosen the valve a bit.

Final Adjustment of Rebound

Once the suspension damping is adjusted, it is necessary to ride the motorcycle to determine whether the setting is comfortable. This is a personal preference and depends somewhat on the rider's style and the type of roads he or she typically rides on. Thus, a test ride should be made on the same types of roads that are typically ridden on.

Even after the suspension damping is made, based on the shock rebound, it can still be adjusted to suit the rider's preference. Adjustments of two clicks or half a turn in either direction should provide enough of a difference for the rider to tell. Take notes of all adjustments made and how the ride feels after each adjustment so that it is possible to return to the "best" adjustment for that rider.

Adjusting Compression

Rebound affects how fast the shocks return to a neutral position after being compressed. Compression damping affects how quickly they compress. Check the motorcycle's owner's manual for the exact location of this adjustment, but note that it is normally located at the bottom of the front shocks and alongside the reservoir for the rear shocks.

Just as with the rebound dampers, this adjustment is highly subjective. Start by determining the adjustment range, being sure to not over-tighten or over-loosen the adjuster. Set it at the 75 percent open and ride the bike. Then set it to 75 percent closed and ride it again. These two benchmark points should provide an idea of how the adjustment affects the ride. From there, make any necessary adjustments to make the compression comfortable to the rider.

Keep notes of adjustments made and how they affected the ride. This allows the suspension settings to be returned to the most comfortable position without having to search for it.

Replacing Motorcycle Shocks

Motorcycle shocks are long-life parts that do not need frequent replacement. However, as with any other shock absorber, the seals can wear out, allowing the hydraulic fluid to leak. If this happens, the shocks need to be rebuilt or replaced.

Not all motorcycle shock absorbers are rebuildable, although some are. It is easy to determine which ones are rebuildable by the availability of a rebuild kit. If no rebuild kit is available, then the shock absorber needs to be replaced. When replacing shocks, the settings described in this guide need to be applied to the new shock.

Buying Replacement Motorcycle Shocks on eBay

Numerous motorcycle shocks are available on eBay. The best way to find replacement motorcycle shocks on eBay is to do a keyword search in eBay Motors that includes the make, model, and year of motorcycle, along with the word "shocks." For example, searching for "2002 Honda Gold Wing Shocks" provides a listing of only those shocks that fit a 2002 Honda Gold Wing motorcycle.

There are many advantages to buying motorcycle parts on eBay Motors, including the ease of finding just the part you need without having to drive around town looking for it. eBay sellers also offer competitive prices, and many provide free shipping. If you have a question about a particular part, simply contact the seller using the appropriate link on the listing. To evaluate eBay sellers, refer to their Feedback score, which is represented by a numerical value in parentheses next to the seller's user ID.

Conclusion

While many motorcycle riders are satisfied with the factory suspension settings, performance bike riders adjust just about everything on their bike, including the suspension. This allows them to fine-tune the vehicle's suspension to match their riding style, weight, and the types of roads they ride on.

There are three major adjustments for motorcycle suspensions: sag, rebound, and compression. The front and rear suspension need to be set separately. When making these adjustments, it is important to eliminate as many variables as possible. In other words, make only one adjustment at a time, testing the ride of the bike after each adjustment. If multiple adjustments are made without test-driving, one can never be sure of each adjustment's effects.

It is also a good idea to write down every adjustment made, along with the effect it had. This will allow returning to a previous setting without having to experiment all over again. It is common to make adjustments in stages, checking the ride after each adjustment. This means going past optimum, and then trying to get back there. Unless you take accurate notes throughout the process, it can be extremely challenging to find that optimum point again.

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