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Suspension Fork : is "pre-load" the same thing as "rebound" ?
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
is "pre-load" the same thing as "rebound" ?
If not, what is the difference.
Thanks
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Preload is how stiff the fork is when you compress it.
ie more preload equals less squash when you sit on the bike.
Rebound is how quickly the fork springs back to its original length after its been compressed by hitting a bump.
Obviously it's a bit more technical than this but in basic terms thats about it.
No. They are completely different animals. Preload is the force aplied to the spring when it is at rest to achieve a desired amount of sag. Adding more preload to the spring will result in less static sag, and less preload = more static sag. Adding preload will make it harder for the fork/shock to move initially, but spring rate determines how fast/slow the spring compresses through the rest of its travel. Add or subtract preload to achive your desired amonut of dynamic sag.
Set the preload to achieve the correct sag as described by the manufacturer. If you can not achive the correct sag you may need a different spring rate if it is a coil spring. If it is an air spring, add or subtract air using a shock pump.
Rebound is the speed that the spring returns to full extension after being compressed. A slow rebound speed can have the fork/shock pack down on multiple hits (can not return fast enough to provide effective damping), and an overly fast rebound setting can have the fork/shock pogoing after hits (returns that fast that the wheel bounces up and down off the ground) which reduces traction.
When setting rebound/compression, start with the dials in their middle position and experiment from there. Try to get your suspension balanced also (have front and rear rebounding and compressing at similar speeds). Find a section of trail that you are familiar with and ride it with the clickers in the middle settings. Make small adjustments (one or two turns at a time) then ride again and see whether it feels better or worse and turn clickers accordingly.
I hope I have not dribbled on for too long and bored you to death.
Too many people wind their preload in thinking it changes the "stiffness" or compression rate. It doesn't
as Melonhead says it simply sets the sag.
A 500lb spring will still take 500lbs to compress it 1 inch. When you sit on the bike your weight will cause the spring to compress a bit. Preload adds a little bit of that load to the start and for want of better terminology, simply counter acts that compression .
You want some sag. bumps go down as well as up.
for xc it is usually 10-25%. for AM it's 25-35% for DH it's sometimes up to 40+%
S, had a great in depth post about suspension set up over on rotorburn. It;s a little DH orientated but worth a read
http://www.rotorburn.com/forums/showthread.php?1...