beansbaxter

Motorcycle Suspension Setup
Getting to Grips with a Black Art

Suspension Set-up: The basics

Whether you are a road rider or a racer correct suspension setup is the key to fast smooth riding and consistent lap times. To get the best out of your bike it needs to be set up for the conditions in which you will be riding. It is considerably easier to set the bike up for the Track as you know what conditions will be like for the next hour or so and thus you can dial in the optimum settings for the that particular situation.

To what extent you change your suspension settings will depend on whether your bike will also have to cope with riding on the road. Unlike Roads Tracks are generally smooth and grippy. So if you are only going to use the bike on the track you have the luxury of fitting harder springs and modifying the fork and shock internals. If you ride on the road as well as the track you will probably want to keep a certain comfort level and concentrate on just optimizing the current equipment

With incorrect suspension setup, tire wear is increased and handling suffers, which in turn can result in rider fatigue. Lap times can be dramatically slower and in extreme cases safety can be compromised. Hopefully the following guide will help you dial in your suspension for faster and safer riding both on and off the track.

Firstly you will need to check the Fork and Shock sag: this is the amount the forks and rear shock settle under load. To measure it do the following: push down on the forks a number of times to settle them, then mark the stanchion with a felt pen or put a cable tie where the dust seal is sitting. Next ask some for help to lift on the bars so the front wheel is just off the ground and measure the amount the forks have traveled down. This is the static sag (or unladen sag), This can be changed by adjusting the spring preload (more preload = less sag). Repeat the same process for the rear, this time measuring the distance from the wheel spindle to a fixed point on the tail. Now you are ready to begin setting up your suspension. The key is to do it a little at a time and make notes as you go. For road riding start with the wet track settings and work from there.

Basic Setup: Check the following

Forks sag 18-22 mm for dry track, 23-27mm for rain.

Shock sag 8-10mm for dry track, 10-14mm for rain.

Check chain alignment. If not correct, bike will crab walk and sprocket wear will be increased.

Proper tire balance and pressure, starting with 30psi front and 32psi rear (both dry and wet).

Steering head bearings and torque specifications - if too loose, there will be head shake at high speeds.

Front-end alignment. Check wheel alignment with triple clamps. If out of alignment, fork geometry will be incorrect and steering will suffer.

Crash damage, check for proper frame geometry.

Stock Suspension Tuning Limitations

Manufacturers plan on designing a bike that works moderately well for a large section of riders and usages. To accomplish this as economically as possible, they use valving with very small venturis. These are then matched to a very basic shim stack which creates a damping curve for the given suspension component. At slower speeds this design can work moderately well, but at higher speeds, when the suspension must react more quickly, the suspension will not flow enough oil, and will experience hydraulic lock. With hydraulic lock, the fork and/or shock cannot dampen correctly and handling suffers. The solution is to re-valve the active components to gain a proper damping curve. It does not matter what components you have, (Ohlins, Fox, Kayaba, Showa) matching them to your intended use and weight will vastly improve their action. Furthermore, if you can achieve the damping curve that is needed, it does not matter what brand name is on the component. Often with stock components, when you turn the adjusters full in or out, you do not notice a difference. In part, this is due to the fact that the manufacturer has put the damping curve in an area outside of your ideal range. Also, because the valves have such small venturis, the adjuster change makes very little difference. After re-valving, the adjusters will be brought into play, and when you make an adjustment, you will be able to notice that it affects the way the way the fork or shock performs.

Another problem with stock suspension is the springs that are used. Often they are progressive, increasing the spring rate with increased compression distance. This means that the valving is correct for only one part of the spring's travel, all other is compromise. If the factory does install a straight-rate spring, it is rarely the correct rate for the weight of the rider with gear. The solution is to install a straight-rate spring that matches the valving for the combined weight of the bike, rider and gear to the type of riding intended.

Remember!

1. Always make small adjustments, more is not always better.
2. Always keep notes of what you have done.
3. Suspension tuning is an art - be patient

Trouble Shooting Suspension Problems

Adjustment locations: Forks
Rebound adjustment (if applicable) is located near the top of the fork. Compression adjustment (if applicable) is located near the bottom of the fork. Spring preload adjustment (if applicable) is generally hex style and located at the top of the fork.


Lack of Rebound
Symptoms:

• Forks are plush, but increasing speed causes loss of control and traction
• The motorcycle wallows and tends to run wide exiting the turn causing fading traction and loss of control.
• When taking a corner a speed, you experience front-end chatter, loss of traction and control.
• Aggressive input at speed lessons control and chassis attitude suffers.
• Front end fails to recover after aggressive input over bumpy surfaces.

Solution: Insufficient rebound. Increase rebound "gradually" until control and traction are optimized and chatter is gone.


Too Much Rebound
Symptoms:

• Front end feels locked up resulting in harsh ride.
• Suspension tucks in and fails to return, giving a harsh ride. Typically after the first bump, the bike will skip over subsequent bumps and want to tuck the front.
• With acceleration, the front end will tank slap or shake violently due to lack of front wheel tire contact.

Solution: Too much rebound. Decrease rebound "gradually" until control and traction are optimized.


Lack of Compression
Symptoms:

• Front-end dives severely, sometimes bottoming out over heavy bumps or during aggressive breaking.
• Front feels soft or vague similar to lack of rebound.
• When bottoming, a clunk is heard. This is due to reaching the bottom of fork travel.

Solution: Insufficient compression. Increase "gradually" until control and traction are optimized.


Too Much Compression
Symptom:

• Front end rides high through the corners, causing the bike to steer wide. It should maintain the pre-determined sag, which will allow the steering geometry to remain constant.

Solution: Decrease compression "gradually" until bike neither bottoms nor rides high.


Symptom:

• Front end chatters or shakes entering turns. This is due to incorrect oil height and/or too much low speed compression damping.

Solution: First, verify that oil height is correct. If correct, then decrease compression "gradually" until chattering and shaking ceases.


Symptom:

• Bumps and ripples are felt directly in the triple clamps and through the chassis. This causes the front wheel to bounce over bumps.

Solution: Decrease compression "gradually" until control is regained.


Symptom:

• Ride is generally hard, and gets even harder when braking or entering turns.

Solution: Decrease compression "gradually" until control is regained.


Adjustment Locations: Rear Shock
Rebound adjustment (if applicable) is located at the bottom of the shock. Compression adjustment (if applicable) is located on the reservoir. Spring prelude is located at the top of the shock.


Shock: Lack of Rebound
Symptoms:

• The ride will feel soft or vague and as speed increases, the rear end will want to wallow and/or weave over bumpy surfaces and traction suffers.
• Loss of traction will cause rear end to pogo or chatter due to shock returning too fast on exiting a corner.

Solution: Insufficient rebound - Increase rebound until wallowing and weaving disappears and control and traction are optimized.


Shock: Too Much Rebound
Symptoms:

• Ride is harsh, suspension control is limited and traction is lost.
• Rear end will pack in, forcing the bike wide in corners, due to rear squat. It will slow steering because front end is riding high.
• When rear end packs in, tires generally will overheat and will skip over bumps.
• When chopping throttle, rear end will tend to skip or hop on entries.

Solution: Too much rebound. Decrease rebound "gradually" until harsh ride is gone and traction is regained. Decrease rebound to keep rear end from packing.


Shock: Lack of Compression
Symptoms:

• The bike will not turn in entering a turn.
• With bottoming, control and traction are lost.
• With excessive rear end squat, when accelerating out of corners, the bike will tend to steer wide.

Solution: Insufficient compression. Increase compression "gradually until traction and control is optimized and/or excessive rear end squat is gone.


Shock: Too Much Compression
Symptoms:

• Ride is harsh, but not as bad as too much rebound. As speed increases, so does harshness.
• There is very little rear end squat. This will cause loss of traction/sliding. Tire will overheat.
• Rear end will want to kick when going over medium to large bumps.

Solution: Decrease compression until harshness is gone. Decrease compression until sliding stops and traction is regained.

Idaho Wolverine

There are A BUNCH of riders that dont know how to set up there own suspension for there weight and type of riding.

Now throw in the hi speed and low speed compresion settings and this will be damm near perfect.

MissKaos

this is GREAT info! What does "crab walk" mean?

BLIZANTHIMUM

its where the rear tire doesnt follow directly behind the front but off to one side or the other due to mialignment on the swingarm adjusters

stubby

I'm not in total agreement with these settings. Tire pressure varies upon brand and conditions. For sag it depends upon your riding style, and stock or aftermarket springs/valves. Using settings from the internet and/or magazines will sometimes work but normally only serve as a starting point. If you don't know about suspension email someone like Jason at Corporate Suspension and he will help you learn - even give you a good starting point for your weight and style of riding.

For a good explanation on sag check out On The Throttle TV - Dave Moss knows his stuff. If you go to race tech's web site you can see what the stock springs are set up for. My 1k was setup for a 220lbs rider - there for the only way to adjust my bike was to get a spring for my weight. If anyone tells you to back preload all the way out - walk away as they don't know much about suspension.

reinaldo

Thank you for sharing this piece of advice. I'm really fond of riding this motorcycle and I had to go and get a new motorcycle air ride suspension but the problem is I don't know how to set this thing properly. Never thought that I will increase my fatigue when this suspension is not properly set up. Overall, these are good tips.

loopy

not trying to cast stones stubby but thats what jason did to my bike last season . he backed my preload all the way out . and used the compression and rebound adjusters to control the spring rate till i had proper springs .

stubby

Key phrase "Till I had the proper springs"

He isn't a magician and attempted to make something work. That doesn't mean it was correct though. If it was correct, you wouldn't have bought proper springs. You paid for a service, so he had to make the current setup the best it could be.

Ryan@IdahoSportBikes

I'd like to know who wrote this guide and when it was written.

Simple misunderstanding between you two.

For the $40 tune you got as close as was possible when you didn't have the correct equipment. Jason still made it known your spring is an issue yes?

Stubby is saying if a guy didn't say your spring is keeping me from making this correct but I'll get as close as we can with what we have for a $40 tune (which I'm guessing is where Jason was coming from), then you should walk away.

In other news, loopy's suspension needs works, race him before that happens hehe WHAT?!?

I'm sure you already plan to replace that spring, pay the $40 again & after that just make tweaks based on your tire wear patterns. You'll be set & loving the way your suspension feels!! Try to stick to the same brand and model of tire as well. I mean... if you want to try and keep it simple & reduce the amount of time you spend tweaking & tuning. If you like to try new stuff & aren't worried about the extra tuning then play away!!!

loopy

i know i was just poking fun ryan lol just getting a laugh but yes he did the best with what i had last year . and it was money well spent

Waldo

I have ALWAYS be told to set the race sag first (this is the difference between you fully geared sitting on your bike and the bike with the wheels off the ground). Once you have the race sage set then check your static sag. The static sag tells you if your spring rate is correct for your weight.

Ryan@IdahoSportBikes

It's differences like these make made me wonder who wrote it and when it was written.

If the person writing it was trying to appeal to basic street riders or racers the contents could vary... Just depends how technical they want to get or if they even have experience tuning race bikes it could lack a lot of content.

Waldo

It almost looks like some of it is missing. Maybe it was writen for a mag, then copied to a website. During the copy process some was edited out.