Suspension Tuning, Part 2

Once sag and preload are set, now is to set suspension damping. If spring exerts force dependent on how much its compressed, damping is to control the speed of the motion. There are two kinds of damping, compression damping and rebound damping. Compression control the speed of the shock or forks to compress while rebound control its speed to re extend after its compress. With no compression damping; the shock or fork will compress quickly, while no rebound damping the fork will extend back almost immediately. Just like a pogo stick, bouncing all over the place.

Proper damping setup will make the bike stable, especially under high speed performance riding. Some bike and after market parts even have further setup like high speed and low speed adjustment, this not to be confused with the speed of the bike but the speed of the suspension travel.

Andrew Trevitt in his book, Sportbike Suspension Tuning, recommend to adjust the rebound damping first since it is easier to set then to set the compression damping. Further more one can adjust te rebound damping while the bike stationary, not like compression damping where you need to ride the bike for further adjustment.

Also, damping adjustment is more subtle and dynamic effect compare to preload and sag adjustment, so experimenting is important.

The rebound adjuster in my CBR is at the top of each forks like the pic bellow.

To adjust them, the book recommends to push the front end of the bike down while engaging the front brake. Let go and measure how long it took for the clip on to rise and return to its position. With proper adjustment the clip on will settle on its position in about 1 second. If less then 1 second then the rebound damping is too soft, and if more then 1 second the rebound damping is too stiff.

I found my setup for front rebound damping 2 turns from full stiff. Standard CBR is 2 1/2 turns from full stiff the same with SR magazine recommended setting. 

For the rear rebound adjustment, similar with the front, but now push the rear shock as in the top picture. I found that my rear rebound damping is 1 1/2 turns from full stiff. While standard CBR 2 turns from full stiff. SR recommended setting is 2 1/2 turns from full stiff. Bit different there.

So far I have made adjsument for the sag, preload, and rebound damping. Next shall be the compression damping…



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