[Closed] Coil shock, more preload or more HSC?

Do you need to change rebound damping when you change the coil?

I'd say 500 will be more "poppy" and from what I've read, a higher rate could be used for more "jumpy" stuff whereas a lower one would be less so

Yep, you'd want to increase LSR and HSR when increasing spring rate - if you didn't touch HSC or LSC.

Where I'm struggling is what effect preload actually has on the stroke.

Preload just allows you to set the sag properly - your weight on its own might not be enough to give the sag figure you want on a spring that is capable of supporting the travel intended

Adding preload allows you to adjust the force applied to the spring so that when your weight is added, you get the right sag. Many different spring rates & pre load combinations will allow you to get the right sag...the question then is how will the spring support you through the travel and how well does the shock need to be damped

And really - if I was setting the sag, the compression and rebound values wouldn't come into it

Compression damping (if you've got the right spring and preload) shouldn't be too high for regular every day riding

Depends on what you are trying to achieve? Is it bottom out control as preload won't affect that.

Yeah, to get a plush feel without bottoming out is proving difficult.

So... Preload won't affect bottom out?

I'm assuming that I either need more HSC or a higher spring rate.

The riding I do is generally steep, rooty and muddy. Barely anything to Huck.

So... Does that mean I don't want to be storing energy in the spring, rather dissapting it through more HSC?

I'd be ok with a coil bottoming out - it's not an air shock so you don't get that progression at the end

I ran an XFusion Vector HLR which allowed you to alter the IFP pressure and volume independently and gave a bit of control over the bottom out. I'd also be looking to play with the HSR to make sure you weren't getting packed down after you bottom out

And also to add - what frame is it on, and how does the leverage curve look at the end? May be that the frame isn't really right for a coil shock so although you can get a coil that's plush through the travel, there's no support at the end.

Again - preload doesn't affect that

Was sent his link earlier that helped: http://www.sportrider.com/technicalities-spring-rate-and-preload#page-5

have you actually accurately measured sag?

also remember that more HSC will affect how it reacts over roots

I ran a 400lb with three turns of preload but prefer the shock with a 450lb spring and very little preload. I probably bottom out but I've never actually felt it.

Yep, measured sag as (e2e - sagged length) / stroke

Get ~30% with 500 at almost no turns

Get ~30% with 450 at around 2.5 turns.

that's not how you measure sag. take the difference of i2i length (19mm for me) and divided by stroke x 100. so for me that's (19/63)x100 = 30.1%. If I do it your way I get 31.2.

Sag is a static measurement, and would not be affected by any damper settings.
To find the right spring weight is more about leverage ratio and your weight.

most coil shocks should not need much compression damping, but a small amount of HSC will allow you to use a spring that is not EXACTLY right for your weight. IE: if the spring is too light for you, more compression damping aids in the spring slowing at the end of it's stroke.

The LSC damping circuit (if there is one) is only about taming the spring for less 'bobbing' if that sort of thing concerns you. With a coil shock, most of the usefull tweaks are in the rebound circuit.