Setting Sag-- Why Bother?

[nhchris]

So here is my question...

If we are going to adjust pre-load up n down to get what "feels right" when riding, why bother to initially set pre-load for 45mm of sag?

Is the sag setting a motorcyclist myth or what?

[Cogswell]

21 minutes ago, nhchris said:

So here is my question...

If we are going to adjust pre-load up n down to get what "feels right" when riding, why bother to initially set pre-load for 45mm of sag?

Is the sag setting a motorcyclist myth or what?

Sag is the baseline setting with your particular weight on the bike.  Easier to reach your desired outcome with a known quantity than just poking in the dark blind so to speak.

Preload setting will vary according to total suspension travel, you typically want about 30%

[betoney]

1 hour ago, nhchris said:

So here is my question...

If we are going to adjust pre-load up n down to get what "feels right" when riding, why bother to initially set pre-load for 45mm of sag?

You don't set sag for  "what feels right", you set the compression and rebound damping for that.  Preload sets tension on the spring and gets it in a height to determine if it is the correct spring rate range for your weight.  (I'm very loose with the terminology just to give you the basic idea).

[dazzler24]

To quote the summary from someone with expert knowledge...

• Setting the sag allows the bike to have the correct compromise for dealing with both bumps and holes. Preload adjusts sag (and so ride-height), not stiffness. However it can change stiffness in unexpected ways due to rebound springs and progressive linkage systems
   
• Too much sag/too little preload will make the bike feel: harsh on bumps, twitchy (front) or slow turning (rear).
   
• Too little sag/too much preload will make the bike feel: skittish on bumps when accelerating (front) or braking (rear), twitchy (rear) or slow-turning (rear).

I'm thinking that these dot points answer your subject heading directly.  i.e. this is why you bother. 🙂