The Tuesday Tune Ep 11: Adjusting Spring Rate vs Compression Damping

Jan 24, 2017 at 13:44
by Vorsprung Suspension  
The Tuesday Tune 11 - To Adjust Spring Rate or Compression Damping?

by VorsprungSuspension
Views: 8,568    Faves: 70    Comments: 9


This episode of the Tuesday Tune is dedicated to one of the questions we regularly get asked: whether the rider should adjust spring rate or compression damping to achieve a desired effect. This week in the Vorsprung Suspension workshop, we're looking at some of the considerations that determine whether you might want to adjust your spring rate (eg. air pressure or coil spring stiffness) or adjust your compression damping.

A large part of the difficulty in differentiating between the effects of compression damping and spring rate is caused by the fact that the forces generated by the spring are acting in the same direction as the forces generated by the compression damper. As a result, increasing spring stiffness and increasing compression damping both have overlapping effects in that they both make the suspension feel firmer in some way. However, because the spring is an energy storage device, whereas the damper is an energy dissipation device, the way that they generate these forces and the way that affects the feel of the bike vary considerably.

Because of this, increasing compression damping has effects that overlap with the effects of increasing spring rate in some ways (bump harshness, travel usage etc), but also overlap with the effects of decreasing spring rate in other ways (stabilizing/deadening the bike). We take a look at how you can understand these effects so that you can pick the most appropriate adjustment to make when you feel that your suspension isn't quite performing at its maximum potential.

As always, the purpose of this is to explain some concepts, and it is important to realize that every fork and shock has adjustments that behave in slightly different ways, so this is far from a conclusive array of "If XYZ then do ABC" statements. Not all adjusters are effective everywhere in their range of clicks (some adjusters stop doing anything before the dial stops turning), and the variation in damping forces that they can produce can be drastically different from one product to another, as some adjusters offer a broad range of adjustment and others are very much for fine-tuning within a narrow band. In other cases, you may run into limitations with stock air spring curves when running above or below certain air pressures, that cause disproportionately large issues once you firm them up or soften them beyond a certain extent.

MENTIONS: @VorsprungSuspension


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72 Comments
  • 22 0
 Very useful information. Thanks!
  • 10 2
 Great video and explanation! A couple of ways to see which combos (relative adjustments to a figurative standard) produce what characteristics, but this is one of them.

+spring & +damping --> for faster riding (racing!)
+spring & -damping --> for more lively ride (park?)
-spring & +damping --> for more controlled ride (rough trail)
-spring & -damping --> for stable/slow riding (unknown/blind trail riding?)
  • 10 1
 I think you're somewhat on the money there. I'd add that quite often, running low spring AND low damping rates is typically suited for novice riders in most situations, or more experienced riders on faster, smoother, flatter trails where big hits are less of a concern and small bump/traction becomes the priority - basically anywhere that you don't need a lot of support.
  • 2 0
 Yeah, I wish I knew this earlier. I mistakenly thought that having rock hard spring/damper rates would make flatter trails more fun and faster, but it is at the expense of dynamic ride height, making the bike feel weird and unwieldy. Finding that balance is quite the journey! Something I left out was that +spring/+damper offers a higher theoretical dynamic ride than -spring/-damper but riding faster actually makes the effective dynamic ride lower. Likewise, a slower trail and/or rider would benefit from the lower dynamic ride of the -spring/-damper rates than "normal".
  • 1 0
 Is it correct to say that you have less range of adjustment to play with on the spring rate side of things? I'm really used to the bike's geometry with around 33 per cent sag so if I'd like to increase bottom out resistance without having to re-adjust my position on the bike too much I'd have to look at the damping settings, right? (Unless it's an air shock with volume adjustment).
  • 3 0
 @theminsta Park is +spring & +damping. Machine buffed trails don't require much negative travel and being stable off big jumps is crucial. The last thing you want off a 35 foot booter is more 'pop'.
  • 6 0
 @bonkywonky: Pretty hard to quantify really - the difference between 33% sag and 22% sag is a roughly 50% increase in spring rate, but both of those are within the spectrum of sag settings that people use. What you could consider is increasing spring rate by similar percentages front and rear, which will largely preserve your steering geometry although you will be a little further from the ground. Beyond that, yes damping is where to look.
  • 2 0
 @VorsprungSuspension:
if i understand correctly it is possible to use rebound damping to settle down the ride height when going fast. If i increase mid to highspeed rebound damping, i could leave my low speed rebound lively and have a bike that is poppy, lively when going slow for technical riding and settles down for high speeds?
By the way i would love to see a corset air can for manitous mcleod. Its hydraulics seem to be working really nice and are easily tuneable by everyone who really tries, but it´s let down by its air can design having no auto balance ports and a small negative air chamber. Should make one of the cheapest shocks one of the best (in my opinion anyways)
  • 1 0
 @cmkneeland: I only ride +spring & +damping so everything was just a super rough approximation. And the concept of it was that you can store more energy into the spring for higher boosts instead of having energy dissipated via the damper. So if you're comfortable on the jump/bike and want to boost the booter, the pop isn't a bad thing Smile Also, more negative travel --> -spring. The (park?) one was +spring/-damper
  • 1 0
 @Krafkloot: +spring rate, +HSR/HSC damping, -LSR/LSC damping makes for a very lively but huck-friendly park setup. The +spring rate acts as a preload platform in place of the LSC yet your bike is springy.
  • 2 0
 @VorsprungSuspension
Need some help here. My new bike (new school geo) tends to go nose high/rear landing on jumps. I try different setups, but didn't work. My current setup feels really good on trail but i lost some confidence on highspeed jumps. Feels like the rear uses too much travel when i pump take-off ramps. Any advice?more rear lsc? More rear hsr? Heavier spring? Or maybe it's a body position issue? Never felt that on previous (older) bikes. Thanks guys
  • 1 0
 Have you tried simply less rebound on the shock??
  • 1 0
 @Robo88: yes I try less LSR. Doesn't work and feels worse down the trail
  • 3 0
 Never rule out body position - technique can compensate for a bad suspension setup, but a good suspension setup can't compensate for technique! Also keep in mind that any advice you get from us or anybody else on the internet is effectively blind, and we could well be missing a hidden cause of your problem. For example, if your spring rate is very soft and your bike is very progressive, that could be causing a sudden ramp up and kick at the end of the stroke which can pop you forwards, but if your spring rate is really stiff, that could also be causing you the same issues. So please take any advice with a grain of salt and make sure you test any changes very carefully, ie don't go making big changes then hitting 40ft doubles straight up! Depending on what adjustments are available to you, try increasing the compression damping on the rear of the bike, or increasing the spring rate or rebound speed at the front of the bike.
  • 1 0
 @VorsprungSuspension: Thanks for the advice!
  • 2 0
 hey @rcksurfer , i had the same issue coming from old smaller geo to a new trek slash. it was amazing on the trails but the first jump almost tossed me. I increased rebound damping till it was soo slow, it worked on jumps but a bit harsh on bumps. i found it had a little too many tokens and like steve said it was ramping up at the end of the stroke (top of the jumps) then rebound pushes harder and kicks the rear end, great for front flips, bad for podiums. i made it a bit more linear with the less tokens and added more pressure, which helped a lot. however the big help was adding a Vorsprung Corsette! it felt strange cause it sagged more than before but it also felt like it had more support or dynamic ride height, and it became more predictable on jumps! hope you find the balance!
  • 2 0
 Nobody ever talks about pumping platform. While the bike can be harsher, more compression can give you more pump, which is what makes you faster. Funny because this is the most fundamental part of riding and is the least mentioned part
  • 2 0
 @VorsprungSuspension
I know it is an old conversation but it is still an actual topic.
I have switched to an Coil Shock (Ohlins) for my Spec Enduro 2021. I bought the sping 571lbs suggested for my weight (200lbs ish) and the bike felt good but I was bottoming out too often to my taste. The compression was almost all the way up and the rebound too.
I decided to go stiffer (600lbs spring) but the bike feel stiffer and I need to run the LSC all the way down. Not too sure what to do. I am thinking about going back to the 571lbs ...
  • 1 0
 That's what i experienced too and then i bought progressive coil and it solved all the problems!
  • 2 0
 @VorsprungSuspension
So I always seem to be getting kicked forward when I jump what would be an ideal place to start in adjusting my suspension to help reduce that effect
Could be I suck at hitting jumps
  • 3 4
 Since you are feeling the rear end of the bike buck you forward after take off, you just need more rebound in the rear.
  • 4 0
 If you're getting kicked forward, that usually means that either
a) you are incorrectly preloading/offloading your bike during take-off (for example, letting your front wheel's momentum react independently from the rest of the bike and the rider),
b) your front suspension's rebound damping is too heavy (relative to what you expect) and/or
c) your rear suspension's rebound damping is too light (relative to what you expect).
  • 24 0
 First things first - no amount of suspension setup can fix improper technique, so start by making sure your technique is solid, then by checking the following:
1. Fork sag is less than rear end sag. I generally recommend starting with a roughly 2:3 ratio, so if you're running 30% in the rear, try 20% in the fork.
2. Fork rebound is as fast or faster than rear end rebound. You can scale them both up and down but the rear end should not be faster than the front.
3. Compression damping in the rear is sufficient to prevent the rear end blowing through its travel when compressing into the jump. Not every shock has useful adjusters that give you lots to play with here, so work with what you've got.

You can take anything too far though - lock out the rear end of your bike and it'll jump pretty sketchy, run fork rebound crazy fast and it'll be sketchy, way too much sag at either end and it'll be sketchy, follow anyone wearing armour outside their jeans down A-line and chances are it'll be sketchy too Smile
  • 1 2
 @VorsprungSuspension: LOL Joeys!!
  • 2 0
 I would add to the technique thing, If you are feeling like you are being kicked forward and landing front heavy, you might be pulling up on your bars during the takeoff. The jumping moment is in the hips/legs not in the arms. Counter intuitively pulling up on the bars during take off causes your center of gravity to move forward with respect to the bikes, resulting in the front end diving. If you find you often land with the front slightly off straight it is a dead giveaway that you are doing this, the slight turn of the bars is due to the muscular asymmetry of your left and right arm. If you are doing this and would like some exercises to stop it then post and I will elaborate.

Another way your question could be interpreted, if you are landing fine but find you are getting 'bounced' forward over the bars then knock a couple clicks off the rebound in the shock, or add a couple to the fork. Personally my fork stays the same and compression damming doesn't often get changed from run to run, but I will take 2 clicks on or off the rebound run by run depending on weather it is the big jump line or a rocky tech trail
  • 1 0
 @VorsprungSuspension: soooo... Rabbit or turtle?
  • 5 0
 @Mikladesh2: hare or tortoise?
  • 2 0
 spending some time on a dirt jumper is a way to separate technique problems from suspension problems
  • 1 0
 @ntd14: hi, that happens to me sometimes. would so love to hear what exercises you'd recommend to counter pulling on the bars!
  • 1 0
 @Mikladesh2: Jackaloop or terrapin
  • 2 0
 @VorsprungSuspension: thanks for that
  • 2 0
 Thanks Steve, this is great.

What's your thoughts about setting air spring pressures based on dynamic sag using something like a ShockWiz or equivalent? Good idea? Bad idea?
  • 2 0
 Definitely worth trying if you have the means. The difficulty is always going to be isolating one adjustment parameter from the others, the ShockWiz may (or may not) help you distinguish between them.
  • 1 0
 Question. you said "In other cases, you may run into limitations with stock air spring curves when running above or below certain air pressures". This is particularly interesting to me. My wife just got a new bike that is equipped with a fox float x. She is only 125lbs maybe 130 riding weight. Harsh bottom outs in the rear is a major issue. We've already changed the volume spacer to the second largest (they are on back order couldn't get a bigger one) and it is still an issue. We can't add any more air pressure because the fork is correct and we don't want to throw off the balance (she already runs less sag than recommended). Is this a product of her being at the lowest end of rider weight for that shock? Would adding a little high speed damping help (she keeps the low speed set at 1 because it gets harsh and dead after that.) Go to the largest volume spacer? Throw the shock out and get an X2 float? Thanks
  • 3 0
 Increasing volume spacer size would be the first order of the day. What frame is this on?

The issues referenced regarding stock air spring curves are primarily to do with initial harshness caused by the air spring's high initial stiffness if you increase pressure beyond a certain point, or late-stroke harshness caused by excessively soft/progressive setups. These issues are more common with heavy riders than light riders, because the HSC damping is doing proportionally less work relative to the loads the spring is dealing with.
  • 1 0
 @VorsprungSuspension: Thanks for the quick response! It's on a new Yeti SB6 frame. She's in a good spot for sag right now, maybe riding a little high. The shock is blowing through the travel on lips/landings, pumping, and if she pushes in to berms. It's a hard bottom out too although the second biggest volume spacer helped with that a bit.
  • 1 0
 steve, I run a fox rc4 with low comp damping at lowest since I use a stiff spring. I like low sag but good small bump compliance. rebound on the fast side of the moon. right? wrong?
I leave the high comp for support on big drops-jumps
thanks
  • 4 0
 My answer here would be "do you like your setup?" Because if you do, you don't need anybody else's approval - there is no such thing as right and wrong here, there is what you like and what you don't like!
  • 1 0
 @VorsprungSuspension any tips Steve (or from anyone!) on how best to approach a fork like my 2014 Marzocchi 888 CR? I'm typically a 'set and forget' rider if i'm being 100% honest but.. i'm trying to learn more, and get the most out of it-this video is great for me in that respect! The CR only has a single compression dial (aside from rebound+preload elsewhere on the fork of course) but is there anything you're aware of about how that fork typically is best set up with the more limited compression adjustment available? is that single adjuster likely to operate akin to a High Speed adjuster or a Low Speed adjuster or is it a true blend of both in operation? I'm typically riding natural terrain, not park, racing or large features and I haven't come across any huge issues, but I'm sat here wondering if there's still room for improvement.
  • 1 0
 I believe it's low speed compression. So it's small bump compliance. Make a note of how many clicks you have now and then plays around with the knob
  • 1 0
 @shom1: cheers for that. Appreciate it.
  • 2 1
 Configuring the suspension must always take into account all 3 setup components - spring, compression and rebound damping. Only speaking about the two of them is not correct because they always interact together - change one and adjustment to the other will be needed as well:
- spring controls what force is needed to compress it;
- compression damping controls how the spring compresses;
- rebound damping controls how the spring returns to its original position.

Without any damping the spring will just oscillate uncontrolled. A good rule of thumb for setuping MTB suspension is:
- use the spring to adjust the sag and control bottom-out - it's pretty easy with today's tech (bottom out tokens). No compression adjustments yet;
- adjust the rebound - fork the fastest you are feeling comfortable with. Shock - check this out www.youtube.com/watch?v=BiHQd4mzl3Y Still no compression adjustment yet;
- After configuring the spring and rebound is time to fine tune how the suspension works - this is done with the compression and the article here explained it good.
  • 7 0
 For sure everything needs to be taken into account, we covered the order of operations for setup in one of our previous videos actually. This video was in response to people who have already got a reasonable setup (spring/rebound/compression) but want things a little firmer or a little softer, and are unsure as to whether they should make changes to the spring rate or the compression damping to achieve that.
  • 4 0
 The hubris in talking up a brother who owns a business in the suspension industry about suspension...

?
  • 1 0
 My Fox 36 Float Fit4 3 Pos came at 150mm of travel with a 160mm air shaft. I kept it at 150 of travel but removed the neg plate spacer in order to increase the volume of the negative chamber, a bit like you do with the now famous Luftkappe. It decreased the level of harshness for small to medium impacts but I still find it to be harsh despite running no LSC (which also makes it a bit too divy for my liking...)

So, how do I achieve more sensibility at the beginning of the stroke and more support?
I have tried lower pressure combined with more tokens which made the fork even more divy and reduced ground clearance... not good!

In your opinion @VorsprungSuspension should I:
1) purchase a 180mm airshaft in order to be able to further increase the volume of the negative chamber?
2) change the shim stack for the E16 version or maybe even a fully custom made stack?
3) do the 2 options above?
4) buy another fork?
5) start playing bridge and stop mountain biking?
6) HTFU?

Thanks again for making great videos and answering questions! Smile
  • 3 0
 I think all your suggestions are good ones. Most forks come with relatively weak HSC damping out of the box, which is quite likely your issue. The E16 tune may help, or it may not. However, first recommendation for harshness is always to check your tyre pressure. If you can lower it without causing other negative side effects (flatting, burping, rolling around on the rim, rim damage etc) then do that before anything else.
  • 1 0
 @VorsprungSuspension: great! Thanks for the tips Smile

By the way, do you or know about somebody machining shorter neg plate tubes for the 36 Float's air spring?
  • 2 0
 @Happymtbfr: Yes... I had some Prototypes made, which screws onto the lower neg air shaft plate, or the 10mm spacers screw onto to reduce the volume. This lowers the negative plate by upto 20mm which vastly increases the softness of the initial stroke. Look on my profile to see the mod (photo 13347845) compared to the standard Fox part (13347842).

I expect Fox will do something similar this year and add the NA2 style of air spring (air equalising dimple in inner stantion, rather than air transfer shaft)

@VorsprungSuspension: have you ever tried modifying the negative plate position on the FOX 36 NA1?
  • 1 0
 @notphaedrus: nice! If you remember the thread size, it would make things easier for me to get someone machining a new shorter neg plate tube.
  • 2 0
 @Happymtbfr: I think it is a metric optical thread. I just took the part of the fork and the machine shop matched it...
  • 1 0
 OK guys i have a question if somebody is willing to help me out. I have Manitou minute pro 140mm (2013model) , im riding hardtail and most of the trail im on is all natural, couple of drops, mostly steep rocky sections, while i have it set up 25%sag with the damping in the middle (more on the +) so what would be the "ideal" setting, im 75kg. Thank you in advance.
  • 1 0
 Only you can find the "ideal" setting...
Try to find things you like and don't like and make adjustments accordingly.
  • 1 0
 Back in the day with spring suspensions, good for small bumps, bad for everything else. Also good for the top cap on the fork blowing out, and the whole assembly hitting you it the face. I don't think they ever expected people to take things very far, but now they probably do.
  • 2 0
 This is honestly my favourite television show at the moment.
  • 4 1
 haha! I had one of the Manitou Magnum forks about 17 years ago that used to do that. Plastic topcaps FTW.
  • 1 0
 What about finger and palm pain? Many suffer it when riding hard on braking bumps in parks. I've got feeling that more high speed compression damping makes ride harsher but prevents finger from pain. Am I right?
  • 3 0
 It can be any of a number of things. Too high a tyre pressure, too much LSC, too much HSC, not enough HSC, too high a spring rate, too low a spring rate, very stiff bars, brake setup, brake power, bars too low, rebound too slow, rebound too fast, grips too large/small or too firm, rider strength/fitness, etc etc. There are a lot of variables there.
  • 3 0
 Great stuff as always. Thank you.
  • 1 1
 Spring rate should always be set to the weight of the rider so that sag settings are correct and once the spring rate is correct the damping is adjusted for the speed, how aggressive the rider is and what terrain they ride.
  • 3 1
 Nice work again Steve, you sure do compress a lot of information into these videos.
  • 3 0
 Thank you again. As always, very helpful.
  • 1 2
 Im going to get slated but there was something about him talking that made me not want to watch the whole vid so he may have answered my question.

Sag.

Increasing or decreasing your spring rate is going to put your sag levels out of whack and no fiddling with damping adjustments is going to alter that.

Is sag no longer important?

Cos if you get your sag set at your preferred amount to start with then thats your spring rate sorted and the rest is just spinning dials to set the comp and rebound as you desire.

Yes you may go up or down a little on spring rate depend on course, weather etc but nothing that would require anthing more than a couple of clicks of your adjuster to accomodate for.

Im in position, of being built like a gorilla so usually its just a case of getting the appropriate sag level by whacking in the max air pressure or stiffest spring i can get and then revalve the fork or shock to work with that spring rate.

People just seem to over complicate suspension adjustment - not saying he did as i didnt watch the whole vid.

The hardest part to working with suspension is getting hold of all the fiddly little bits the companies dont want you to have and spending the time / having the confidence to take things apart to learn how they work and how adjustments effect them.

When your paying a suspension company most of the time its not for the fact that the work is particularly difficult but the fact that they have the knowledge.

Oops that turned inti a semi rant...sorry
  • 1 0
 ....and ive just read thru all the comments and vorsptungsuspension has pretty much answered all of the above...DOH!
  • 5 1
 Fair question, and something we have covered in some of the other videos regarding spring rates/sag in some depth, but to answer directly what you're asking: sag is a useful measurement, but not a critical setup parameter in its own right. In other words, getting the spring rate in the right ballpark is necessary, but ride height is way less critical on mountain bikes than it is on say cars - because for bikes, the vehicle's centre of mass is very high, the wheelbase is very short (compared to other vehicles), and the rider's own body motions control the ride height immensely. So in that regard, sag is useful as an indicator of spring rate suitability relative to rider weight, but even then, some people like to run more sag with more progression at the end of stroke, and some like to run less sag with less end-stroke ramp up. Some WC racers ride ~20% sag on the rear end of their 200mm DH bike, which is 40mm of sag at the wheel. Santa Cruz used to recommend as much as 40% sag on the earliest iterations of the V10 because they were so progressive, which meant 100mm of sag when measured at the wheel. Both setups are rideable even though one is effectively 2.5x as much sag as the other in absolute terms.

Also, if you find the videos boring, by all means feel free to let us know - anything that helps us improve them is appreciated. Negative feedback leads to more improvement than positive feedback does Smile
  • 1 1
 @VorsprungSuspension:
Cheers for the reply. I didn't watch the vid all the way thru. it wasn't that it was boring I think it was just me. I tend to rather prefer to read articles rather than watch vids anyway.
Get what you saying about sag, all my bikes, Mx and road as well, are set up differently.
On a different matter what's the most common cause of blown forks and shocks that you see. I got a theory it's lack of maintenance or poor set up rather than defective products?
  • 2 0
 @VorsprungSuspension
Thanks will have to work on once the snow go's
  • 6 4
 i like to be stiff when I compress
  • 2 0
 Great again as always, thanks!
  • 2 0
 more of these and less politics!!!
  • 1 0
 No one enjoy landing on the front wheel. Errr.... ever heard of Bernard Kerr ? Big Grin
  • 2 0
 yyyeeeesssSSSSSSSS
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