Suspension Tuning, Part 1

All right, lets talk about suspension. As I mentioned at earlier post, I just got my self a Sportbike Suspension Tuning book by Andrew Trevitt. I look forward to learn about suspension setting and try to implement the knowledge I gain to my sportbike.

I highly recommend the book, especially if you interested to know about sportbike suspension. The basic concept of Spring, Damping, Geometry and so forth are all very clearly described. Good stuf!! If you want to learn about sportbike suspension go get a copy of this book.

The first setting that I will try is to set my bike “sag” and adjusting its “preload”. This shall be the first step in suspension setting. I have my bike suspension set already at my club. That setup will become one of the reference for me to do this setup. I have: the standard CBR setup from CBR Owners Manual, my club setup, and a recommended CBR setup from Sport Rider magazine.

Sag shall be a starting point for suspension to work. So setting sag properly will ensure that the suspension work on its recommended range. The book shows how to measure sag for both front and back. With the help of the pit mechanic I measure and its involving measuring the front fork tube while you on and off the bike. I found the front sag to be about 22 – 23 mm.  Bit low but normal for race track use. With this kind of sag you will need then to adjust the preload accordingly.

For less sag, you will need stiffer preload, while for more sag the preload need to be adjusted softer. Based on the sag measurement of my bike I will then need more sag. Thus I will need to have softer prelaoad setting.

Prelaod setting at my CBR are at the top of the front fork. I will need 19 mm wrench to adjust it as in the top picture. I use the recommended SportBike setting, which apparently similar with the setup that I have used. Which is 10 turn counterclockwise from full stiff. This will be my front preload setup.

As to rear preaload, the adjustment was bit tough as it hidden at the rear shock. But after checking the setup, the measurement are the same from the standard CBR setup with the recommended by SportRider and what I have used which is position 4 from full soft. Bellow pics shows its location:

Now, I have set the preload which is 10 turn counterclockwise from full stiff for front; and position 4 for the rear. Next shall be the rebound and compression damping.

STAY TUNE!!

12 thoughts on “Suspension Tuning, Part 1

  1. Looking forward to reading the updates on this!

    Also remember that suspension settings can change from track to track, or even day to day at the same track. So while setting your sag is an important first step, be aware that you might constantly be changing suspension settings even from a morning session to an afternoon session at Sentul.

    From my experience I’ve had to adjust very little on the CBR600RR. Usually we’ll just show up at the track and ride it, making very minor (if any) suspension changes throughout the day. Good luck.

  2. Hi Troy..

    Just got back from my track day, and only focus today on the rear compression damping as there were big different between CBR standard setting (from its owners manual), what recommended from SR Magazine (July’08 Super 600’s) with the setting from my club.

    Standard suspension setting for rear compression damping is 20 clicks from full stiff. From SR Mag is 14 clicks from full stiff, while my setting was 5 click from full stiff. To be honest I did not felt much different, perhaps I did not ride fast enough? I do felt OK with 5 clicks and also ok with 14 clicks.. I did not try the 20 clicks though.

    Any idea where in our riding should we check about the rear compression damping?

  3. Obviously, I don’t know what the track conditions are like at Sentul, but who recommended to go to 5 clicks? I’m not saying that he’s wrong because I’ve never ridden that track, but you should be able to tell a difference between 20 clicks and 5. Generally, the smoother the track surface, the stiffer you want the suspension and vice versa.

    When you exit a corner and apply the throttle, does your bike tend to run wide? If so, that’s a result of the rear squatting under acceleration, taking weight off the front tire, meaning the front has less traction and is forced to run wide. To remedy that, stiffen the rear compression damping. That will make the rear squat less and help the front tire go in the direction you want to.

    That’s just one way to check the rear. What’s your bike doing in the back that you’re not comfortable with?

  4. Thanks for the input Troy..

    I will certainly check out my corner exit during next track day. Sentul’s track is bumpy, and with the new track patch and such it certainly not smooth.

    My next problem is a lot of “head shake” during acceleration or when hitting bumpy surface. Adjusting steering damper is not possible in the CBR since they using the electronic steering damper.

    Will certainly jotted down more info during next track day!

    Cheers!

  5. Mr. Bona,

    I want to ask about sag number 22-23mm.

    I have from another book is by percentage; 25%-33% of available travel range for rider sag, if ride hard pick a value closer to 25%, so more travel available for hard braking.

    What is your front end total travel measurement?.

    Thanks,
    bengkelsepedamotor

  6. Hi Mr. Bengkelsepedamotor..

    Sportbike Suspension Tuning book do not use persentage for sag measurement. I do not know the reason, but the book recommended 25mm – 30mm for track use and 30mm – 35mm for normal riding.

    As for suspension travel, stay tune for the next post!

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