[djjohnr]

I sent off my shock to Push for a rebuild and decided to get it re-valved while I was at it. I requested the DH tune, with notes indicating I preferred my suspension set-up for high speed rock gardens and fairly stiff low speed compression for cornering. The shock came back yesterday including a card with recommended settings. Interestingly the suggested rebound setting is way slower then I'm used to.

I normally tune my rebound to return as fast as possible without creating excess chatter. My main concern is keeping the tire on the ground as much as possible. Bucking isn't something I've had to worry about tuning out of my past few frame/shock combinations - stock mid/high speed stock tune has been good enough to let me run the rebound as fast as I want without fear of bucking. Whatever the case, Push seems to have a different idea about rebound.

Have other people found that the suggested rebound setting from Push was relatively slow compared to what they normally run? Results? Unfortunately I'm sick and it's raining - doesn't look like I'll be able to ride to test it for another 2 weeks

UPDATE

Update for those that have followed this whole thread -

I was finally able to get out and ride/test this weekend. I considered some some A/B testing trying to find my "old" rebound settings, but I think that it would be a crap comparison as too many variables have changed. I did match the rebound on the fork to the new rear valving so it was possible for me to A/B that and comment.

Bottom line - The suggested "slower" feeling setting kept the chassis more stable (as expected). This setting did not create packing issues on the rear or the front of the bike, the suspension stayed responsive. The conditions were either muddy or tacky, so I can't really comment if it improved overall traction or not - I'll need to wait until it's dry for that analysis.

 

[Bicyclist]

When I sent my shock to Push a while ago I remember this being the case. I ended up compromising and running it about halfway between where they recommended and where I used to run it.

 

[Commencal-guy]

I was in the same boat as you were. I got my DHX 5.0 push'd and the rebound was ridiculously slow. They told me the faster you hit impacts the faster the rebound increases. Even with zero rebound dampening the shock was still too slow for my liking. I eventually got rid of it and bought a Vivid 5.1

 

[PUSHIND]

Hey guys. Figured I'd chime in to give a little input.

With a Factory Tuned DHX from us you have two rebound components. First is the low speed bleed which is what you adjust using the external dial. This dial simply opens and closes a single port in the center of the piston. Second is the rebound ports in the piston. These piston ports are covered by the shim stack which is arranged based on the spring rate and stroke. This port and shim stack arrangement acts as an automatically adjusting orifice system that changes based on spring load and input speed.

If you run the external adjuster too far open (faster), you reduce the pressure being applied to the shim stack at the piston therefore not allowing it to open as effectively to dump fluid at higher speeds. By running the external rebound adjuster towards the slower side you get less suspension deflection a lower speeds increasing traction and control and more fluid flow at higher speeds due to the piston opening more effectively.

Darren

 

[LambMan]

They told me the faster you hit impacts the faster the rebound increases.

I used to run my rebound faster until I got the Dirt Fundamentals dvd. In the section on suspension setup, the video said that most world cup riders run their rebound really slow, just a few clicks from the slowest setting. I decided to try it and found that I got WAY better traction on roots and off camber. Since then, I've heard other pros on videos talk about how they run the rebound slow. I've found that with the rebound set this way my tires actually stay in contact with the ground more than with the rebound higher. The draw back is that it's more likely to pack up and have a harsher feel through extended high speed hits.

 

[djjohnr]

Hey guys. Figured I'd chime in to give a little input.

With a Factory Tuned DHX from us you have two rebound components. First is the low speed bleed which is what you adjust using the external dial. This dial simply opens and closes a single port in the center of the piston. Second is the rebound ports in the piston. These piston ports are covered by the shim stack which is arranged based on the spring rate and stroke. This port and shim stack arrangement acts as an automatically adjusting orifice system that changes based on spring load and input speed.

If you run the external adjuster too far open (faster), you reduce the pressure being applied to the shim stack at the piston therefore not allowing it to open as effectively to dump fluid at higher speeds. By running the external rebound adjuster towards the slower side you get less suspension deflection a lower speeds increasing traction and control and more fluid flow at higher speeds due to the piston opening more effectively.

Darren

Darren - thank you for the response!

So if I'm reading this right, if the rebound bleed valve is too far open, there isn't enough pressure to fully utilize the rebound shim stack. However - wouldn't this result in rebound speeds that are slower then optimal near the beginning stroke where the spring rate is relatively low? Could you get around this by using a smaller diameter bleed valve?

 

[Delimeat]

About 4-5 years ago I was given some advice from far more knowledgeable sources than myself regarding slowing down the rebound and I've never looked back. The difference in traction and confidence is insane.

Most riders who give my bike a push exclaim that "... it must pack up all the time!"

The area where I do most of my riding isn't exactly smooth, but it's not crazy rough either, and I quickly discovered that "packing up" here was just not going to happen. EVER. And as it turns out, even when I'm riding places that are as rough and fast as anywhere any of us would ride a DH bike, there is no packing up there either. We are not riding Motocross here, its bicycles and we are just not hitting things that are that big in that much succession.

inb4 Monkey who has to tell me that he is hitting bigger stuff faster and harder than Bubba.

 

[tacubaya]

Interesting....

 

[EVIL JN]

I have been feeling almost the same thing but beeing a rock shox guy i've setup my beginning stroke rebound quite slow and the ending a bit faster, so it dosent pack up to easy and the bike just feels more planted than having both e/b rebound more to the faster side.

 

[General Lee]

I shared pit space at a World Cup a few years ago with a bunch of British guys way faster and skilled than my self. We go on the topic of suspension and one of them made the comment that fast rebound seems to be a N. American thing (not sure if that's true or not since I don't know what you all do in Europe), and that slower was better at least for racing. Partly for traction and partly for chassis stability. I prefer my rebound pretty slow on my DH bike as well, much slower than any of my other bikes.

Tron Brosnan said in a recent interview recently that since teaming up with Hill he's adopted Sam's recommendation to slow his suspension way down.

Take it for what it's worth I guess, since suspension settings will always be personal and dependent on what sort of riding you do. Gracia, on the other hand has said he runs some of the fastest rebound of anyone he knows but that was about 4-5 years ago so who knows where he's at now. . . .

moral of the story: experiment a lot and keep track of what works for you. personally, I've got 2 or 3 settings I use for different mountains around where I live and other than that I don't fiddle with much but it took the better part of the early season to get it nailed down.

 

[PUSHIND]

So if I'm reading this right, if the rebound bleed valve is too far open, there isn't enough pressure to fully utilize the rebound shim stack. However - wouldn't this result in rebound speeds that are slower then optimal near the beginning stroke where the spring rate is relatively low? Could you get around this by using a smaller diameter bleed valve?

Increased low speed compression at slow speeds is desirable to keep the suspension stable during events such as g-outs, heavy cornering, or rider weight transfer.


I also think that the fast rebound thing has come from early suspension components that didn't have the complex damping circuits of today's components. Just a few years ago the majority of mtb suspension components were either port orifice designs, or had such heavy shimming on the pistons that they behaved like a port orifice design. Remember when you would turn the rebound dial full closed on a FOX shock and it would practically compress down and not return? Do that with a current RC4 and notice how this is no longer the case.

Today's components and tuning techniques allow for increased control for handling without the compromise of having the suspension not be reactive enough.

Darren

 

[norbar]

I shared pit space at a World Cup a few years ago with a bunch of British guys way faster and skilled than my self. We go on the topic of suspension and one of them made the comment that fast rebound seems to be a N. American thing (not sure if that's true or not since I don't know what you all do in Europe), and that slower was better at least for racing. Partly for traction and partly for chassis stability. I prefer my rebound pretty slow on my DH bike as well, much slower than any of my other bikes.

Tron Brosnan said in a recent interview recently that since teaming up with Hill he's adopted Sam's recommendation to slow his suspension way down.

Take it for what it's worth I guess, since suspension settings will always be personal and dependent on what sort of riding you do. Gracia, on the other hand has said he runs some of the fastest rebound of anyone he knows but that was about 4-5 years ago so who knows where he's at now. . . .

moral of the story: experiment a lot and keep track of what works for you. personally, I've got 2 or 3 settings I use for different mountains around where I live and other than that I don't fiddle with much but it took the better part of the early season to get it nailed down.

The euro thing seems pretty strange as unless someone messed with the rebound dial on my dhx air I haven't touched it since it came from mojo tune when I was servicing it with them. It is really fast now and I was considering slowing it down.

The thread is a good read though I think I may experiment with the settings when the new gear finally arrives (it's been ages)

 

[MarkDH]

Yeah interesting thread, I got my Vivid a few months ago and I thought I had it working pretty well, but I'm keen to experiment with this slow rebound now. Just a bit of a dummy question here though, if I increase the preload on my spring, is it likely that I will need to slow the rebound to retain the same susp characteristics? I'm thinking yes but I don't know if it's just in my head, it seemed to bucking back at little more just hitting kerbs out in the street.

 

[Steve M]

If you run the external adjuster too far open (faster), you reduce the pressure being applied to the shim stack at the piston therefore not allowing it to open as effectively to dump fluid at higher speeds.

Interesting comment - is this a transient effect based on force required to open the shims vs force required to hold them open (at the same point/degree of opening)? Because the way you phrased that, it sounds like you're actually saying that (presumably for a given shim configuration) running the low speed rebound further open would somehow actually increase high speed rebound... which to me seems impossible, unless the transient act of opening the shims requires so much more fluid pressure than holding them open, that it more than makes up the difference in flow and pressure caused by having the LS bleed further open. I couldn't imagine the shim stack having that level of inertia, friction or material damping to actually cause that effect though. Can you clarify this for me?

 

[davep]

Wondering the same thing. That statement definately made me scratch my head.

 

[stringbean]

i used to run my sus ridiculously fast, decided to have a play around with it one day and now running it a few clicks above the minium and the differance has made a massive differance to the way im able to ride. at first i was skeptical to try it but now im glad i did.

 

[4130biker]

I've always run mine really fast, but I'm interested in trying this out. I'm assuming that one would proportionately slow down the fork rebound as well.
Was it Sam Hill that I read somewhere likes his springrate low and rebound slow?

 

[$BMFB$]

I'm assuming that one would proportionately slow down the fork rebound as well.

yea, would this apply to your front suspension as well?

 

[djjohnr]

Increased low speed compression at slow speeds is desirable to keep the suspension stable during events such as g-outs, heavy cornering, or rider weight transfer.

Agreed. What I'm wondering about is low speed (end-stroke) rebound.

Today's components and tuning techniques allow for increased control for handling without the compromise of having the suspension not be reactive enough.

No matter the technology, we're still trying to balance chassis stability with a return rate fast enough to follow the terrain. Through trial over time I've found that the best balance point for me has been faster then the recommended rate included on my card. That said, I'm looking forward to some more in-depth testing then some quick runs down the muddy hill behind my house with this new set-up. However, if I wind up finding I prefer faster low speed rebound, is my high speed rebound now going to suffer?

Here is a good article that sums up how I approach setting rebound - http://www.sportrider.com/tech/146_9604_tech/index.html

 

[Jm_]

I don't think you can compare many OEM shocks, especially older ones, to something Push or any other high-end manufacturer makes. I know that if I closed down the rebound on my old foxes and other shocks, they sucked. I don't know if they could flow enough oil through the high-speed circut, but for whatever reason, it really didn't work. Same thing with most of the compression controls, as they often did not do anything positive or simply destroyed the overall ride. With my avalanche, it "feels" slow, the recommendation is to turn the adjuster 8 clicks from full "slow", but at high speed it rebounds fast due to the high speed circut. My point is that you can't compare OEM fox and other products that simply do not work as well as the high end/ custom stuff that is avail today. What any one user "did in the past" may simply be due to the limitations of their shock. If the high-speed rebound circut isn't set up properly (light enough, flows enough, etc), closing down the free-bleed rebound would lead to massive packing and very poor performance.

 

[4130biker]

yea, would this apply to your front suspension as well?

Seems like it would, if you're going for chassis control, but I would be interested to hear from someone who knows more about suspension setup than me.

 

[Jm_]

Seems like it would, if you're going for chassis control, but I would be interested to hear from someone who knows more about suspension setup than me.

Maybe, but is that front-suspension high-speed rebound circut tuned correctly to allow for this? Will it flow enough oil? Does it have the right blow-off force? If not, I can't imagine this "idea" will work for crap.

 

[4130biker]

Maybe, but is that front-suspension high-speed rebound circut tuned correctly to allow for this? Will it flow enough oil? Does it have the right blow-off force? If not, I can't imagine this "idea" will work for crap.

So let me get this straight:
Avalanche or pushed fox or canecreek whatever in the back with variable rebound rate, then a boxxer or 40 up front with no such thing? How is this chassis control? Is it reccomended to have a slow rebound rear with a fast rebound in front?
What are the European guys doing in this respect? I'm sure they don't all have "non OEM" forks.
It seems to me that the suspension should somewhat "match" front to rear for chassis control, but I could be wrong.
Not being sarcastic, I'm just curious.

 

[RoboS]

As far as I know the same technology is in the forks. When I saw video and description on Mojo site http://www.mojo.co.uk/forxaction.htm
I tried to slow down rebound on shock and fork. Now it's much better, I feel much more confident on bike and ride is a lot smoother, while I'm much faster than before. I ride 36RC2 Float and DHX5.

 

[Udi]

Wondering the same thing. That statement definately made me scratch my head.

Same here, I'm glad everyone's being so polite about it, because my first thought was "that definitely isn't correct".

Interested in hearing PUSH's response.

 

[davec113]

I had a PUSH tuned DHX on my last bike, and it was a big improvement. I recently got a Session 88 w/ DHX and Fox 40. Yesterday, I tried slower rebound settings than I'd normally use at a local dh spot. I tried to set it up close to what PUSH sent back to me on my last bike. It did increase stability and traction and I did not notice the sus packing up. Since I never tried the bike with relatively fast rebound settings, I can't say it was a huge difference, but moving from medium to slow(er) did make for a positive change.

 

[LambMan]

Seems like it would, if you're going for chassis control, but I would be interested to hear from someone who knows more about suspension setup than me.

No. It's always better to run the front suspension relatively fast. This prevents the fork from packing up and giving you a diving sensation when cornering or doing the scorpion in a steep and extended rough section. I'd suggest that anyone wanting to learn more about suspension setup get the dvd Fundamentals that Dirt mag put out. Theres a really long section on suspension setup. I'm no suspension expert, but learning just a little about how to set it up correctly made a huge difference in my riding and confidence on the bike. Traction is good.

 

[PUSHIND]

Can you clarify this for me?

Wondering the same thing. That statement definately made me scratch my head.

Same here, I'm glad everyone's being so polite about it, because my first thought was "that definitely isn't correct".

Interested in hearing PUSH's response.

With a square bump you get very short duration with very high velocity at the damper. With a lot of our setups that use a preloaded high speed stack, running the low speed bleed slower will allow the preload of the stack to be overcome more easily allowing the shims to deflect, therefore decreasing rebound forces and making the force curve more digressive.

yea, would this apply to your front suspension as well?

As someone else mentioned, front to rear balance is very important.

Agreed. What I'm wondering about is low speed (end-stroke) rebound.

Calling low speed end stroke, or high speed beginning stroke is pretty generic as both of these types of events can happen anywhere in the stroke.

No matter the technology, we're still trying to balance chassis stability with a return rate fast enough to follow the terrain. Through trial over time I've found that the best balance point for me has been faster then the recommended rate included on my card. That said, I'm looking forward to some more in-depth testing then some quick runs down the muddy hill behind my house with this new set-up. However, if I wind up finding I prefer faster low speed rebound, is my high speed rebound now going to suffer?

The bottom line is what makes you as a rider feel comfortable on the bike. We make recommendations, but if you prefer a different setup it's okay. It's also important to remember that no one has the ability to tell you, whether from this forum or friends that you ride with, if your setup is right or wrong. If it makes you comfortable and controlled than it's the correct setup.

Here is a good article that sums up how I approach setting rebound - http://www.sportrider.com/tech/146_9604_tech/index.html

Funny....that article is written by my buddy Paul who is one of the key people behind me starting PUSH.

Darren

 

[djjohnr]

Calling low speed end stroke, or high speed beginning stroke is pretty generic as both of these types of events can happen anywhere in the stroke.

This is the part that I'm confused on. I've thought (quite possibly wrongly), that the main forces at work on the rebound damper (other then oil pressure) are spring rate (how compressed the spring is) and how much resistance there is against the rear wheel. Under that assumption I'd have the most rebound force when the spring is fully compressed and the least when it is fully extended. It sounds like that assumption is wrong. Can you elaborate on how you can have a low speed event deep into the travel?

Also, I want to make sure you don't think I'm being combative, I'm just trying to understand my suspension better. It's wonderful that you're coming on here to answer these questions - it's greatly appreciated.

During the few mini-runs down the hill I've done so far, I've noticed a drastic improvement in the compression damping range - it's nice and firm until I hit something size-able and then it opens up beautifully - just what I wanted. Rebound is harder for me to test when it's this muddy though.

 

[4130biker]

Couldn't you have a low speed event deep in the travel by hitting successive bumps?

 

[LambMan]

Here is a good article that sums up how I approach setting rebound - http://www.sportrider.com/tech/146_9604_tech/index.html

Great article! Great thread too. Who thought people could discuss their varying opinions constructively on the internet?

 

[nh dude]

for starters. i had to slow down my dhx 4.0 on my glory to match the 09 40 cartridge that replaced the 06 40 cartridge ( no it wasn't blown ) i had. i found that the fast end of the newer cartridge was really slow on my spectrum of fork rebound. i also found that i could run the rear rebound on my glory really fast compared to my r9 and still control the bike.

other rules of thumb
1.for both- pick the bike up a couple feet and drop it on the wheels. when it lands it should NOT bounce. it should just squat into the travel and then return. if one wheels bounces more than the other significantly tune that ****.

2. for the rear shock-find a big curb 8" +. roll off the curb walking speed sitting down on the bike in the seat and keep rolling . as you are rolling pay attention. the rear suspension should compress (duh), rebound and then compress slightly 1 more time then "platform out" to its original normal sagged spot.
pay attention on the rebound/return. it should only return once and not that fast, but fast enough to be @ platform out within the next bike length.

3. do really huge bunny hops and see if the back end is to active or dead for your taste on the way up

4. then ride your lab rat trail to figure out it real world.

 

[Capricorn]

yeah, i do that curb test as well to generally get within the ball park of my shock's rebound setting. Tends to work pretty well.

 

[!xobile]

I've had 2 shocks and 1 fork worked on by Push. Everything I've had worked on by Push has been exceptional. I was skeptical about the rebound settings at first as well, but after a couple of days riding I was sold on their suggestions. If there is one thing I have learned from conversations with the guys at Push, and other suspension people is that a parking lot test is pretty useless for determining the characteristics of suspension out on the trail. Just my $0.02, and as said earlier its really a personal preference.

 

[davetrump]

i think as blanket statement most people set their rebound up too fast, and most people only focus on the compression end of things when evaluating how their bike responds to bumps.

for instance, everyone has ridden a section of trail that has made the rear end feel like it is skipping out or generally harsh, and assume that their compression is to firm.

a lot of folks would be surprised if they slowed the rebound down a bit and hit the same section of trail how that would affect the ride.

it is good to see these things being discussed rather than debated as there is no right answer. the key is to test and test some more on a trail that has varied terrain and that you know well. that way you can evaluate how changes to suspension effect the ride on different terrain.

as for the fork question... a lot of folks prefer to set the front end a bit stiffer and with a bit quicker rebound than the back end.

keep in mind that hopping up and down in a parking lot to check balance does not equate to what you will get on a steep trail where the weight bias is moved much farther forward.

the idea is to find a balance between maintaining geometry, stability, traction, and comfort... everyone puts these priorities in a different order, but that is the order i usually start with.

 

[DirtyMike]

With a square bump you get very short duration with very high velocity at the damper. With a lot of our setups that use a preloaded high speed stack, running the low speed bleed slower will allow the preload of the stack to be overcome more easily allowing the shims to deflect, therefore decreasing rebound forces and making the force curve more digressive.

.

Ok, I see were your going here. It makes sense to me when I think of the avy independant hi/low comp adjuster and how it works.....Basically they are not totally independant and do affect each other if the setting are too fasr off.
If I am reading this correct, what your saying is that once the shims deflect/open, they stay open until the rebound stops<IE next compression stroke> Am I correct in how I am readig that?

 

[Pslide]

other rules of thumb
1.for both- pick the bike up a couple feet and drop it on the wheels. when it lands it should NOT bounce. it should just squat into the travel and then return. if one wheels bounces more than the other significantly tune that ****.

I hope your joking!

I think your #4 is a better recommendation...

 

[Udi]

With a square bump you get very short duration with very high velocity at the damper. With a lot of our setups that use a preloaded high speed stack, running the low speed bleed slower will allow the preload of the stack to be overcome more easily allowing the shims to deflect, therefore decreasing rebound forces and making the force curve more digressive.

That's true for compression, but for rebound (which is what we were discussing) from my understanding the return velocity is defined by the spring. And in that context (again, specifically for rebound damping), end-stroke rebound is the same as high speed rebound, because that is where the spring will return at its fastest.

In my experience an ideal setup involves having the low speed rebound reasonably fast to aid in the suspension responding quickly to bumps without packing up, while having enough high speed rebound to prevent instabilities in the return direction (like bucking).

With a properly tuned compression damper (enough LSC) and adequate HSR together controlling chassis stability, I don't see the need to run a lot of LSR, and if anything, to me it would only seem detrimental.

It's pretty hard to gauge how much damping is in question over the internet and like you said, at the end of the day what matters is running whatever helps you ride fast/confident, but I'm interested in hearing the benefits of your proposed setups.

 

[DirtyMike]

It's pretty hard to gauge how much damping is in question over the internet and like you said, at the end of the day what matters is running whatever helps you ride fast/confident, but I'm interested in hearing the benefits of your proposed setups.

Thats something to remember with this discussion as well...Specially seeing Darren is putting in custom shim stacks in his work to match up to the riders, springrates, and riding styles.

 

[LambMan]

I hope your joking!

I think your #4 is a better recommendation...

Why would you not agree with this? If the tire is leaving the ground from a drop like that, you will be losing traction on trail chatter(roots, rocks, high speed repetitive hits). Definitely one of the first suggestions I ever learned on setting up a dh bike.