"Racing is living, everything else is just waiting" Steve McQueen
The Starting LineRacing NewsRacing ResultsInside the GridMotorsports LinksTech StuffCommunityContact UsThe Legal Stuff
Track & Racing tips
Drive
Safety Wiring
Tires
Suspension


Suspension Tuning Guide by Dave Hodges
Street Bike or Road Racing Applications




With incorrect suspension setup tire wear is increased and handling suffers, resulting in rider fatigue. 

Lap times can be dramatically slower and overall safety for both street and race enthusiasts is another issue. 

Add the frustration factor and it just makes sense properly setup your suspension. The following guide 

will help you dial in your suspension for faster and safer riding both on and off the track. 



Basic Setup: Check the following
-Forks/Rear Shock - Race sag 25-30 mm, 1 - 1 3/16 inch 
-Forks/Rear Shock - Street sag 30-35 mm, 1 3/16 - 1 3/8 inch 

-Check chain alignment. lf not correct, sprocket wear is increased. 

-Proper tire balance and pressure. If out of balance, there will be vibration in either wheel 

-Steering head bearings and torque specifications, If too loose, head will 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 



Forks: Adjustment Locations
=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. 



Forks: Lack of Rebound
Symptoms:
-Forks are plush. but increasing speed causes loss of control and traction. 
-The motorcycle wallows 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. 



Forks: Too Much Rebound
Symptoms:
-Front end feels locked up resulting in harsh ride. 
-Suspension packs in and fails to return, giving a harsh ride. 

Typicalty after the first bump, the bike will skip over subsequent bumps. 

-With acceleration, the front end will tank slap or shake violentty due to 

lack of front wheel tire contact. 



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



Forks: 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. 



Forks: Too Much Compression
Symptoms:
1/-Front end rides high through the comers, causing the bike to steer wide. 
It should ride in the middle of suspension travel. 

Solution:
* Too much compression. Decrease compression "gradually" until bike neither 
bottoms or rides high. 



2/-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 chaffering and shaking ceases. 



3/-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. 


4/- Ride is generally hard, and gets even harder when braking or entering turns. 

Solution:
*Decrease compression 'gradually' until control is regained. 


Shock : Adjustment Locations
-Rebound adjustment (if applicable) is located at the bottom of the 
shock. 

-Compression adjustment (if applicable) is located on the reservoir. 

-Spring Preload 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 weavin 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 comers, due to rear squat. 

It will slow steering because front end is tiding 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 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,bike 

will tend to steer wide. 

Solution:
* Insuficient 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:
* Too much compression.Decrease compression until harshness is gone. 
decrease compression until sliding stops and traction is regained. 



Stock Tuning Limitations:
New motorcycles purchased from the dealership are generally set-up on the soft side, 
for a rider in the weight range of 140-165 lbs. If you are not in this range, you 

must retune the suspension tor your weight within the internals of forks and shocks, 

the manufacturer puts valve with small venturis. This, along with shims, creates a 

damping curve. This works okay at slower speeds, but at higher speeds, when the 

suspension must react more quickly, the method cannot low enough oil and you experience 

hydraulic lock. With hydraulic lock, there is no damping. The fork and/or shock cannot 

dampen correctly and handling suffers. The solution is to revalve the active components 

for the proper damping curve. It does not matter what components you have, (Ohlins, Fox, 

KYB, Showa). If you can achieve the damping curve that is needed, it does not matter what 

brand name is on the component. Sometimes with stock components, when you turn the 

adjusters full in or out, you do not notice a difference. This is due to the fact that 

the manufacturer has put the damping curve in an area outside of your ideal range. After 

revalving, the adjuster will be brought into play, and when you make an adjustment, you 

will be able to notice that they effect the way the fork or shock perform. 



One of the problems with stock springs is, in most cases, it is of a progressive rate. 

This is to say, a spring at sag may be .85 kg per mm, and at 2.5 inches of travel, it may 

be 1.05 kg per mm, getting progressively stiffer. The ideal solution is to install a sprig 

with a straight rate, specific for your weight, and the weight of your motorcycle. In some 

cases, the factory installs a straight rate spring, but often the incorrect rate for your 

weight. 



Dave W. Hodges 

Circuit One Suspension



Here is a link to a great tech article on shocks and how they work by Marcus McBain of Rpsraceteam.com.... very informative!



All images and article content courtesy of Marcus McBain/Rpsraceteam.com

An overview:
  "This document is provided to give you a complete understanding of how your shock works. Over time, as you gain experience on the track and begin to become proficient in understanding how to adjust your shock, this overview will provide insight into what the shock is doing internally. Just as important, you will also be able to understand what your vendor is or should be doing to provide support and service for your shock.
 
Most likely 90% of the people that read this don’t honestly know what really comprises the shock’s internal technologies and why it is important to select and then have the shock maintained for optimal performance. This article is designed to provide riders, mechanics, and suspension vendors a solid amount of information so that they can understand how a shock works and what exactly goes on in a shock for better long term success.
 
The following material will be presented and discussed in depth to help customers and technicians have a better understanding of the various products and grasp of why a shock “works”

See the full 2 part article here





The Starting LineRacing NewsRacing ResultsInside the GridMotorsports LinksTech StuffCommunityContact UsThe Legal Stuff
2012-2015 soonerbillz.com All Rights Reserved