Suspension SETUP, a 'how to' guide...

PB Forum :: Mechanics' Lounge
Suspension SETUP, a 'how to' guide...
Author Message
flag dmadness
Posted: Jan 18, 2015 at 11:49 Quote
Use hsc for big impacts thats the reason for hsc. Running a stiffer spring ( reasonablly ) is a bad way to compensate as it will make your wheel not track properly, im not making this stuff up, talk to any suspension dealer. A stiffer spring will hold up more under load obviouslly but you wont be as fast generally. Though if you huck badly then perhaps you will save yourself on a bad landing.
flag staike
Posted: Jan 18, 2015 at 12:24 Quote
It's also a lot about personal preference. If I'm in between springs I always pick the stiffest one, the bike gets more responsive and more fun to ride imo... but for some people it's opposite, they choose the softer one because it will give a more controlled ride and they can use the dials more to get everything ...dialed.
flag bikerboywill
Posted: Jan 18, 2015 at 15:04 Quote
In a perfect world I'm all about have a super soft spring and running compression to help with the hard hits and brake dive but in reality I'm yet to ride a fork which can be run soft and with enough lsc to hold it up in its travel without compromising small bump and overall feeling of the fork. I hate the feeling of an over damped fork especially through roots and rocks. I've never ridden an fork with lsc that blows off well enough to allow small bump
flag dmadness
Posted: Jan 18, 2015 at 16:18 Quote
staike wrote:
It's also a lot about personal preference. If I'm in between springs I always pick the stiffest one, the bike gets more responsive and more fun to ride imo... but for some people it's opposite, they choose the softer one because it will give a more controlled ride and they can use the dials more to get everything ...dialed.

I can argree with ya there, it IS about personal preference. I ran an over dampened fork for 3-4 years before I finally saw the light ( for me ) and shaved almost 40 seconds off of a run time and also didn't suffer fore arm fatigue as much. I;ve been riding a demo since 2005 and it is known for being a playful bike. the exception for me is on my endure bike with fox fork that I must add extra air too sacrificing small bump as otherwise it jumps like hell and in bermed corners feels like I will go OTB otherwise, It will be changed for a pike this summer.
flag bikesandfun
Posted: Jan 18, 2015 at 21:31 Quote
Thanks for the suggestions guys

Tried switching a few things up before I went riding today. I'm using a Demo frame with a Ohlins rear shock. According to their spring rate chart I should be using a 343 lb spring. Up until now I've been using a 400 lb spring with 8 out of 17 clicks of lsc and hsc on the middle setting. I like how it feels stiffness-wise for most stuff, but I really notice the lack of small bump sensitivity on the chattery stuff.

So I put on a 350 lb spring and tried that out a bit but found it too be waaay too soft even with a lot of compression. It made the geometry feel completely off (to me) having it sit that deep in the travel. After that I put on a 388 lb spring (so what's recommended for a person 20lbs heavier than me) and did a lap on that with hsc on the middle setting and lsc at 12 clicks out of 17. Surprisingly it felt a lot softer than the 400 lb spring, and a loooot more controlled on the small bump chattery stuff. Although even with a lot of lsc it still sat a bit lower in the travel than I'd like.

I wonder if I should just try using as much lsc as possible until it stops feeling supple or something?
flag bikesandfun
Posted: Jan 19, 2015 at 18:16 Quote
Clarkeh wrote:
-
Well said
flag Clarkeh
Posted: Jan 20, 2015 at 4:24 Quote
bikesandfun wrote:
Clarkeh wrote:
-
Well said
Feel free to quote me anytime.
flag slidways
Posted: Jan 22, 2015 at 19:55 Quote
bikesandfun wrote:
I've been trying to run a bit stiffer suspension setup by running a heavier spring rate than is recommended for my weight (for example, running whats recommended for somebody 25-30 lbs heavier than myself), and having the lsc about 1/3 of the way closed. It feels alright but I'm wondering if running more sag, by using a lighter spring rate, and turning up the lsc a fair bit would offer any benefit to how I have my suspension set up now?

Thanks, and sorry if this has been covered before.

five-10 wrote:
Id go for a stiffer spring and less LSC then, as adding LSC won't make the bike sit higher in its travel but a stiffer spring will.

+1

if you try to run stiffer compression to help a soft spring you tend to end up with a harsh bike that feels pretty average and still blows through some travel. You want to get the right spring rate ideally. If its only 25lbs or 50lbs you can test it, but usually if you have the right spring rate but want more support and the dampening isn't cutting it, your up for a custom tune.
flag shawnmcgr
O+
Posted: Jan 26, 2015 at 12:16 Quote
I've got a Fox DHX4 on an '07 Bullit and need to order a softer spring. Fox calculator says 400lb spring for 30% sag.

Curious if anyone has tried running a longer spring with more pre-load to get recommended sag and more adjustability. The fox manual recommends only 2 turns of pre-load before a spring change is recommended. Running a 3.0 spring on a 2.75 stroke shock would give another 0.25 in of potential pre-load.

I'm considering ordering a 350x3.0. It's only about 20mm longer so there seems to be lots of room on the body. There would be less force at the end of stroke, about 100lbs less. I'm thinking it would be a bit plusher mid travel. I would have to increase to air chamber pressure to increase bottom resistance?

Anyone try this? Experience?
flag staike
Posted: Jan 26, 2015 at 13:02 Quote
It would take away a lot of small bump compliance for sure. Not sure what you're trying to accomplish here? Why not get the right spring and use the suspension design and shock like it was designed to be used? Preload doesn't affect more than the start of the travel, just adding a bunch of preload would probably make the shock blow through the mid travel. Remember, the spring is only supposed to hold your weight, any tuning should be made on the adjusters or a custom tune if you're experiencing problems with the stock valving and shims.
flag Nobble
Posted: Jan 26, 2015 at 13:06 Quote
Having to run that much preload would ruin your sag or spring rate.
flag five-10
Posted: Jan 26, 2015 at 13:48 Quote
Yeah, if you think about it, even a really stiff spring will compress slightly a with a tiny amount of force - at the start of the springs travel.

Preloading a spring forces it past the start of its travel, creating a threshold force that you have to overcome before it will compress any more. This is why preloading a sping makes the small bump of suspension worse.

I only really typed that out because it confused me loads until I understood it, haha.
flag shawnmcgr
O+
Posted: Jan 26, 2015 at 16:13 Quote
staike wrote:
It would take away a lot of small bump compliance for sure. Not sure what you're trying to accomplish here? Why not get the right spring and use the suspension design and shock like it was designed to be used? Preload doesn't affect more than the start of the travel, just adding a bunch of preload would probably make the shock blow through the mid travel. Remember, the spring is only supposed to hold your weight, any tuning should be made on the adjusters or a custom tune if you're experiencing problems with the stock valving and shims.

If I follow the recommendation of Fox there is only a single spring rate available, 400lbs/in. I was just considering trying a different spring rate, but the stock spring size (2.8 ) does not have enough adjustment in it to allow the initial sag to be set properly for any other spring rate.

My thought was a smaller spring rate would increase small bump compliance. Pre-load affects the entire stroke: total force at any point in the stroke = (displaced length + pre-load length ) * spring rate. I would have to add an additional 1/10th of an inch of pre-load on a 350lb spring vs 400lbs spring. Same sag. At the end of the stroke the total force would be about 100lbs less than a 400lbs spring ( 1000lbs vs 1100lbs approx). End result is a slightly flatter spring curve.

For $30 I'll buy both and see how the 350 works, just wondering if anyone else has tinkered with this. My sled has a lot more pre-load adjustment, I was surprised to see such small adjustment available.
flag shawnmcgr
O+
Posted: Jan 26, 2015 at 16:22 Quote
five-10 wrote:
Yeah, if you think about it, even a really stiff spring will compress slightly a with a tiny amount of force - at the start of the springs travel.

Preloading a spring forces it past the start of its travel, creating a threshold force that you have to overcome before it will compress any more. This is why preloading a sping makes the small bump of suspension worse.

I only really typed that out because it confused me loads until I understood it, haha.

When you're sitting on the bike, at the correct sag, you have already overcome the initial pre-load /threshold force.

we'll see how it goes, the only issue I'm concerned about is bottom out resistance and how progressive I need to make the end of stroke. I think I can adjust the air volume to increase the progressiveness.

 


Copyright © 2000 - 2024. Pinkbike.com. All rights reserved.
dv56 0.016566
Mobile Version of Website