Fred's suspension article in the COG Mag

[stewarth]

Hey Fred, read your article the other day and decided to go out and compare my settings. While I did record some initial settings, I played with them a lot during my last track day and my record keeping was lax.

Anyway, I'm 220 lbs dry (no gear) so I figure I'm heavier than your closest equivalent rider. My rear preload was 19 Clicks, and front 8mm dead on. Very close to your settings.

My dampening needs tweaking after I get my oil changed as my front is currently turned all the way in.

Thanks, great article and reassured me that I'm in the right ball park.

 

[Fred H.]

If you are riding the bike on the track, you'll probably want to reduce your sag from the "standard" sag settings we found for the 150 lb rider per Kawasaki's guideline in the manual, as well as adjust the rebound damping.

After installing my Ohlins rear shock and Traxxion AK-20 front forks, I've been doing a lot more research and testing on various suspension components and settings. One thing I discovered right off the bat is just how big a difference getting the proper spring rate makes. If you don't have the right spring rate to begin with, no amount of adjusting preload and damping will ever make it right. The OEM springs in the C14 are progressive, so they will cover a larger range of rider weights than a straight rate spring will, but the range of them is still somewhat limited. If you find that the rear still feels soft after adding more preload, or you just can't get the balance of the bike right, you may need to investigate different spring rates, which usually means an aftermarket rear shock will be needed, and possible a change of front fork springs.

The other thing I've discovered while dialing in my Ohlins rear shock, is just how much of a difference adding just 2mm of preload to the rear can make to the whole way the bike feels, both front and rear. Adding preload raises the rear which causes weight to transfer to the front forks and off the rear spring. It also changes the attitude of the bike which will affect turn in feel. Front and rear damping rates may also have to be adjusted as a result of a change in preload, but my advice to anyone adjusting suspension would be that BEFORE you turn ANY of the damping adjustment, FIRST try changing the pre-load settings, since it has such a huge effect. Only after you are POSITIVE you have the preload where you want it, should you start working on the damper adjustments.

Many riders make the mistake of increasing rebound damping too much, because it provides a stiffer feel when you do. The downfall of this is that if the rebound damping is too high, the wheel won't be able to return as fast as it needs to after hitting a bump, and you will loose traction. The spring needs to be able to re-extend the suspension fully, and fast, so that the wheel can stay in good contact with the road surface. If you find yourself spinning the rear tire on corner exits easily, you may need to reduce rebound damping. Another problem too much rebound damping can cause is that the suspension will "pack in" on multiple bumps, because it can't fully extend before it hits the next one. What rebound damping really does is "slow down" the extension of the suspension, so it causes the rebound cycle TIME to be longer in an attempt to reduce "after cycles". Ideally you want the rebound damping adjusted so it minimizes after cycles, while still allowing the suspension to re-extend quickly.

Compression damping does the opposite. It slows down the compression cycles, and if it is adjustable, it can be used to sort of "fine tune" the spring rate, since it works in concert with the spring in slowing down compression.

Another thing I'm learning is that it's almost impossible to make one adjustment of any setting and not have it impact multiple aspects of handling. Which is another good reason to only change ONE THING AT A TIME. Getting a bike dialed in the way you like can take a long time as a result, because there are so many variables at play, and what feels good on one road on one day, may feel terrible when the temperature changes or on a different road. Be patient and make small changes, and test ride and repeat. You'll probably need a dozen or more ride and adjustment cycles to get it right.

But at the risk of repeating myself, FIRST and FOREMOST, get the PRE-LOAD set right before you adjust anything else.

 

[Fred H.]

By the way, one of the things I like to do when dialing in my suspension is to find a good fast corner that has some undulating pavement or a bump in the middle of it, and then go ride through the corner at a pretty good lean angle and see how it handles when I encounter the bump. This is probably the most demanding environment for your suspension, and the most crucial one. If there are any weaknesses or improper settings, this is when they will really become evident.

 

[stewarth]

Thanks Fred, the dialog is very helpful, makes me think about it. Rode this morning at 5am 250+miles and after a quick 75miles and a coffee I revisted my front dampening. Backed it off (full ccw) and then dialed it in until the front didn't bounce when pressed hard while standing still. Then rode and made some minor adjustments...rest of the ride was great.

I think my biggest error so far has been to try and make adjustments in the garage when the oil is cold and settled.