|
Your
bike's rear sag is very important. Too much and you increase the
rake of your forks causing your bike to push to the outside of
the corners or "hunt" for a berm. Also, excessive bottoming
may occur if you have too much sag. Not enough and your bike will
under-steer, possibly headshake and seem harsh in the back. Also,
once you have the correct race sag set on your bike you can tell
if your rear spring rate is correct by the amount of static or
free sag the bike has under it's own weight.
All
but a few riders can really feel their bike bottoming. Most riders
think the damping or the linkage is too harsh. But what really
is happenning is they are running too little preload on the spring
or to soft of a spring and using the last half of the stroke only...
Setting correct spring rates with correct preload and race sag
is very important to your bikes setup...
Setting
your race sag is easy, here is the procedure;
Race
Sag is a measurement of how much the rear suspension sags under
the riders weight compared to no weight on the bike.
The
First measurement is taken with the bike on a center stand with
the rear wheel hanging freely in the air. Measure the distance
between the rear axle and some convenient point near the fender
like a seat bolt.
The
Second measurement is taken with the bike on the ground and the
rider standing straight up on the foot pegs supporting himself
against a wall or tree. Again, me asure the distance between the
same two points used above. (Standing increases the repeatability
of this measurement.
The
Race Sag is the difference between the First and Second measurement.
To
change the sag, use a long punch and a large hammer to loosen
the spring locking nut on the shock. Then turn the preload nut
to adjust rear spring preload. Note: Increasing spring preload
will decrease Race Sag and vice versa.
Changing
the Race Sage to 3 ¾" will raise the rear end making
the bike turn sharper and reduce bottoming. Conversely changing
the Sag to 4 ¼" will lower the rear and increase high
speed stability.
Or
watch it on video...
|
