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DK Custom Front Suspension Testing Report - Part II of II

Front Suspension Testing Report

Part II

In the Test Report Chart we highligted in Blue the AK-20 Cartridge System.  This is one of the top front suspension set-ups in the world, for daily riding, touring and on the race track. 

We highlighted in Green the set-ups that are the best performance for $ spent.



Some Suspension Basics-

Springs are to keep the bike at the desired height when sitting still, and to control (partially)  the amount of compression when hitting a bump.  

It is important to get the right spring weight for your bike and your weight.  You can adjust the sag correctly with too soft, or too stiff of a spring, but with too soft it will dive and bottom easily, too stiff and the ride will be harsh.


Sag- Why proper sag is important-


In most cases Sag can be adjusted with spacers.


Example of what can happen when there is not enough sag-  After the wheel passes over a bump, it can lose contact with the road for an instant...this is because there is not enough rebound length for the forks to extend back down, enabling the tire to stay in contact with the road. This is not such a big deal when going straight, however, if in a corner when a bump is hit, it can be disconcerting to feel the front tire “skip” & then “catch”.  If you’ve ever felt that, you know what I mean.


If there is too much sag (almost all HD’s come from the factory with too much sag), then too much of the travel is used just by the weight of the bike, leaving you with too little travel when riding, resulting in easily bottoming out.



Compression damping is what determines how fast or slow the forks compress when the wheel encounters a bump.


Too fast and the travel gets eaten up quickly, causing bottoming out on larger bumps.  To slow and it makes for a bumpy, or jolting ride.


Rebound damping is  what determines how fast or slow the forks return to “neutral”after the wheel passes over a bump.

Too fast and you have a bumpy ride, too slow and you can lose tire/road contact.


Proper sag and damping keeps the forks riding in the upper mid range of their travel, providing a comfortable ride, a stable & controlled ride, and more clearance (lean angle) in the curves.


Fork oils- We tested a variety, and found that the Maxima Racing Formula Fork Fluid worked as well as any we tested, and better than most.



Ideally you want......

  • The correct spring weight for your weight
  • The correct amount of Sag
  • Limited dive when applying the front brakes
  • Correct Damping in both the compression & rebound strokes


This will result in a smoother, more comfortable ride.  Better braking, less tire wear (cupping), better ground clearance for less scraping in the curves.  Better stability and control at low speeds (parking lots), and more confident at speed due to improved compliance (the tires staying well planted on the road).


Ride Compliance


Compliant means that the suspension fully absorbs the impact of any bump at any speed in order to keep the tires in contact with the road. Doing so minimizes undesired momentum that can cause you to lose control or have the bump feel harsh.





Click HERE for PART I 


Click HERE to see Front Suspension Components


Live Free - Ride Free!