<testing with the shockclock.doc> 2-21-05

Kicking - One of the most common symptoms of poor rear suspension is "Kicking". There are two major reasons for kicking (and it's not what most people think). Most people head for the Rebound Adjuster and slow the rebound down. They think the suspension is compressing and then recoiling uncontrollably. The truth is that 99% of the time Kicking is caused by either:

1. The suspension is TOO SOFT. The suspension runs out of travel, still has energy, loads the frame and deflects off the bump. This happens on the COMPRESSION SIDE of the bump, not the rebound.
   
   
2. The suspension is TOO STIFF. It doesn't use enough of the travel because it has too much resistance to moving (damping most of the time but also could be spring) and it deflects off the bump. This also happens on the COMPRESSION SIDE of the bump.

• About 1% of the time kicking is caused by TOO MUCH Rebound Damping. The suspension "packs down" because there is not enough time between bumps for it to return to it's normal ride height. This means the spring is compressed and the next bump has to overcome this initial force before it compresses. This is a minor "kick" compared to the previous 2 causes.

The problems with test riding:

1. The first problem with human testers is we typically find what we are looking for. If we believe the problem will be fixed by whatever change has been made we will typically feel that it's better, whether it actually is or not. This is one of the reasons why people are still cranking in rebound adjusters.

Oh, by the way, when does anyone ever crank the rebound back out? My experience, never. After all why would they want it to kick again? We commonly find rebound adjusters set at 2 or 3 clicks out from all the way in. It kicked again and they "fixed it" again by slowing down the rebound some more.

If you really want to check this one go out and ride your bike with the rebound adjuster backed out. Obviously, you need to ride with caution. What you will find is that the bike is plusher and the traction might be way better (especially if you're riding on hard-packed) and the bike feels a bit "loose". BUT it doesn't kick! Hmmmmmmm.

2. As far as bottoming is concerned we have found that perhaps 50% of riders can tell if the front end is bottoming but 95% CANNOT tell if the rear is bottoming.

Analysis
From the Main Menu select "View". The first screen is the Bottoming Tab. This displays Soft and Hard Bottoms. The standard setting for Soft and Hard Bottoms is 90 and 95% of the Maximum Available Travel. This is good most of the time. The idea is; Soft Bottoms are OK but you're getting close, and Hard Bottoms are not OK.

The Bottoming Tab will display the number of Soft and Hard Bottoms that have occurred during the entire recording.

The conclusions are simple. If it's kicking and you have Hard Bottoms make it stiffer. If it's kicking and you don't have Hard Bottoms, make it softer.

If you want a more advanced analysis use the "Peaks" feature. The places we have found that have many problems are either where we are using the most travel or where the highest shaft velocities are occuring.

If you want to view the top 10 greatest uses of travel, select the "Peaks" button. It will display the Travel Peaks in decending order, showing the amount of travel used and the time in the recording when it occurred. If you want to see whether it is high speed or low speed, toggle the "joy stick" on the PDA up. This will display the Velocity graph for the same time frame. For dirt bikes you can consider anything over about 0.5 M/s as high speed.

To change back to the Travel graph, toggle the joy stick down.

To see the top 10 highest velocities select the "Velocity" Tab. If you want to see the Travel View for this time frame, Toggle the joy stick up. You will notice that many times the greatest velocities do not occur at the same places the maximum Travel is used (though sometimes they do).

Note on a common misconception:
Many people think the suspension should bottom once per lap. Where did that come from? Think of this; your bike is setup perfectly, no bottoming, great balance, good feedback, good traction, good feeling of control, etc. and you go to a track that doesn't have big jumps or perhaps is pretty smooth. What are you suppose to do, make everything so soft you bottom once a lap? You'll find yourself riding a mush bucket that's hard to control.

By the way, you might want the suspension to bottom, maybe even more than once a lap. You may find the compromise that handles the biggest stuff is just too harsh on the rest of the track and the trade-off isn't worth it. Properly setup suspension is still a compromise. Gold Valves satisfy a very wide range of conditions, but even they are a compromise.

If you are not using all the travel you can make it softer. This doesn't mean you have to make it softer. Keep in mind that just because your suspension isn't bottoming it doesn't mean it is the best it can be. Remember, "The best you've ridden is the best you know."

Stay Tuned,
Paul Thede