How to adust rebound

[mlbco]

I own a '11 GG300 6 Days (Marzocchi Forks, Ohlin 888 rear shock). The forks have been re-valved by LTR and the Ohlin shock is stock. I'm a 170 lb 50 y/o B rider and I'm not loving life with my suspension set up. The rear end seems to kick me around a lot and this may be confusing my impression of the front fork adjustments. My current set up is:

Shock
9mm spring pre-load on the rear shock
Rebound = 25 clicks open
Low Comp = 20 clicks open
High Comp = 1.5 turns open

Fork
Comp = 16 open
Rebound = 10 open

After reading some suspension tuning threads I think I might need to set my rebound properly before I tune anything else and I need suggestions on how to do this (front and rear). I'm planning to soften the compression first so I can focus on the rebound. Any suggestions on what I should do or look for?

Thanks,

Steve

 

[noobi]

The best way to test suspension iv found, is to find a section of track somewhere that you can ride over and over again, to compare the changes.

The rebound adjuster on the zokes is in the top of the fork, compression on the bottom. For the shock, the rebound is the screw on the rhs at the bottom, obscured some what by the linkage, compression are the 2 knobs on the top rhs of the shock body, outer knob is high speed compression, inner screw is low speed.
If the shock is kicking up, turn the rebound on the shock clockwise to slow down the rebound (for the record, counter clockwise speeds up the rebound) Ideally you want the shock to rebound enough to keep it up in the stroke but not so fast that it kicks up. Compression is basically how fast the shock will compress, more click clockwise makes the shock harder to move.
Forks work on the same principle, only they need to have the same settings on each side, so they don't try and fight each other.

I would ride the bike over varying terrain and see what its doing, then change ONE thing at a time, then ride the bike and see if its better or worse. It helps to write down changes and how each suspension setting changes the ride. Its not hard to do, it just takes time.

 

[mlbco]

The best way to test suspension iv found, is to find a section of track somewhere that you can ride over and over again, to compare the changes.

The rebound adjuster on the zokes is in the top of the fork, compression on the bottom. For the shock, the rebound is the screw on the rhs at the bottom, obscured some what by the linkage, compression are the 2 knobs on the top rhs of the shock body, outer knob is high speed compression, inner screw is low speed.
If the shock is kicking up, turn the rebound on the shock clockwise to slow down the rebound (for the record, counter clockwise speeds up the rebound) Ideally you want the shock to rebound enough to keep it up in the stroke but not so fast that it kicks up. Compression is basically how fast the shock will compress, more click clockwise makes the shock harder to move.
Forks work on the same principle, only they need to have the same settings on each side, so they don't try and fight each other.

I would ride the bike over varying terrain and see what its doing, then change ONE thing at a time, then ride the bike and see if its better or worse. It helps to write down changes and how each suspension setting changes the ride. Its not hard to do, it just takes time.

Noobi,

Thanks for taking the time to write a nice tutorial. I know some of the basics of suspension systems but I don't know specifically how to test and adjust the clickers. For example, I have no idea how to tell the difference between a shock that is using the stroke versus one that is kicking me up. I'm hoping people will be able to describe how to tell the difference between these traits so that I can zero in on the adjustments more quickly.

I purchased the Race Tech Suspension Bible book and it only has 12 pages (out of 250) devoted to tuning and they are the least informative pages in the whole book. Most articles I've read about suspension tuning lack simple descriptions and test procedures for iterating on the clickers. What is most needed is a clear description of what each shortcoming feels or behaves like, so that the tuner can identify the trait and correct it. The lack of an informative description of packing, pogo-ing, bottoming, harshness, etc.. results in endless confusion in the tuning process.

In the past, I've used the same set of trails for repeated runs as I change the clickers. This has been important in limiting the number of variables in the test. Now I need to know what to look for and in what order to tune things. My baseline plan is to start off with everything at the maximum soft setting. I will then run the rebound up and down (rear then front) to gauge the effect and hopefully find some nominal settings. Then I plan to repeat this procedure with the low speed compression (rear then front). I have no idea what to do with the high speed compression on the rear shock.

Thanks,

Steve

 

[lankydoug]

My preferred method is to find a gnarly set of whoops and an approach to a corner with nasty braking bumps. I start with the clickers in the middle of the adjustment and ride the section over several times and then change one adjustment 4 clicks and ride the same section several times again. I can't tell one click adjustments but if you go 4 it will either get better or worse and then you know if your going in the right direction. In the whoop section I'm trying the achieve a front to rear balance that doesn't let the front dive and keeps the rear in contact with the ground without kicking. On braking bumps I'm looking for the tire to stay in contact as much as possible without kicking too bad. Once you have it in the neighborhood by going four clicks then go back two clicks to find the center of the sweet spot. Most books say to go one click at a time but frankly I could not usually tell the difference and it would take three rides @ one more click just to know if I was going the right way + it will help you learn what each adjustment does to affect how it rides.

Basically if it blows through the stroke increase the compression dampening. If you can't use all of the stroke decrease the compression dampening. If it kicks back like a pogo increase the rebound. If it packs down and after the third braking bump the tire is skipping you decrease the rebound dampening. Try to set it so that you use all of the suspension in the sever situations.

 

[rgranger]

forks: put a zip-tie on the tubs, see where it ends up after riding though some of the rougher bits, if it is all the way at the bottom, maybe add a click of compression damping, if it is still up high dial some out so that you are using the full stroke.

shock: it is supposed to be alive but not so much that the rebound will pogo your but up into the air. sometimes it is difficult to tell if it is the initial hit or the rebound bouncing the rear up and that is where like the others said, run the same bit a few times and make changes.

Man, when I was 18 none of this mattered, we just rode the snot out of the darn bikes, but that was 35 years ago and I wasn't a pansy like now

 

[lankydoug]

forks: put a zip-tie on the tubs, see where it ends up after riding though some of the rougher bits, if it is all the way at the bottom, maybe add a click of compression damping, if it is still up high dial some out so that you are using the full stroke.

shock: it is supposed to be alive but not so much that the rebound will pogo your but up into the air. sometimes it is difficult to tell if it is the initial hit or the rebound bouncing the rear up and that is where like the others said, run the same bit a few times and make changes.

Man, when I was 18 none of this mattered, we just rode the snot out of the darn bikes, but that was 35 years ago and I wasn't a pansy like now

+1, besides when I was 18 there were no adjustments on the forks or shock. If you wanted to go faster twist the wrist and stay off the brakes. I must say bikes are soooo much better now.

 

[mlbco]

I have a lot of trouble telling the difference between pogo-sticking on the rebound and too stiff on the compression. One thing I've noticed is that accelerating on small, close spaced whoops make the bike slow down a lot because the rear wheel is not in contact with the ground much. I assume this means too much rebound damping because the wheel doesn't extend into the terrain between bumps. I'm already maxed out on the rebound damping reduction, so I'm hoping that I'm wrong on this.

BTW, here I am 36 years ago when nothing much mattered! I loved that RM 125, my first dirt missile.

Steve

 

[noobi]

I have a lot of trouble telling the difference between pogo-sticking on the rebound and too stiff on the compression. One thing I've noticed is that accelerating on small, close spaced whoops make the bike slow down a lot because the rear wheel is not in contact with the ground much. I assume this means too much rebound damping because the wheel doesn't extend into the terrain between bumps. I'm already maxed out on the rebound damping reduction, so I'm hoping that I'm wrong on this.

BTW, here I am 36 years ago when nothing much mattered! I loved that RM 125, my first dirt missile.

Steve

See if you can get someone to watch you, or even better video you, if you cant tell what its doing then its hard for us to help without seeing it. I can for certain say that the rebound should be around the middle setting, not at max anything. You could give LTR a call, and see if he can help you out, he knows what hes doing.

 

[GMP]

First thing that jumped out at me was the 25 clicks out on the shock rebound. Thats waaaay too light, your bike is unbalanced. Go in to 10 - 15 clicks out and start testing again. If your rear is kicking this is likely why. It also loads the fork more, forcing it to work lower in the stroke, making it feel more harsh. Your other settings are in the ballpark, and springs should be fine.

 

[mlbco]

I changed the shock rebound to 15 clicks and things seemed better, but my testing last weekend was in muddy conditions and the ground was much softer than our usual hard pack. My current settings are:

Rear (Ohlins)
HComp = 2 turns open
LComp = 20 clicks open
Rebound = 15 clicks open
static sag = 30mm
spring = 5.3 kg/mm (stock)

Front (Marzocchis w/LTR re-valve)
Rebound = 10 clicks open
Compression = 20 clicks open


I'm concerned that both front and rear compression settings are nearly full soft and the bike is still far from plush. I'd rather have adjusters that allow me to cover the spectrum from soft to hard and these don't. Has anyone modified the Ohlins shock for a more plush ride? I think the shock is still the root of my problems and I've run out of adjustment range on it.

Steve

 

[rgranger]

I changed the shock rebound to 15 clicks and things seemed better, but my testing last weekend was in muddy conditions and the ground was much softer than our usual hard pack. My current settings are:

Rear (Ohlins)
HComp = 2 turns open
LComp = 20 clicks open
Rebound = 15 clicks open
static sag = 30mm
spring = 5.3 kg/mm (stock)

Front (Marzocchis w/LTR re-valve)
Rebound = 10 clicks open
Compression = 20 clicks open


I'm concerned that both front and rear compression settings are nearly full soft and the bike is still far from plush. I'd rather have adjusters that allow me to cover the spectrum from soft to hard and these don't. Has anyone modified the Ohlins shock for a more plush ride? I think the shock is still the root of my problems and I've run out of adjustment range on it.

Steve

When did you have Les do your zokes? He told me that he found out he needed to change things from his early 2011 works. Mine that he did, maybe the frist 2011 forks, came back with almost no rebound adjustment. I sent them back and tested the new stuff last friday before changing any of the default settings, I think that they broke (ok re-broke) my left wrist. I dialed in a lot more rebound damping and that helped a lot and changed the rat-a-tat-tat to more of a thud-thud-thud. waiting to get x-rays back before trying it again. but at least now there is some rebound adjustment, there wasn't much before.

 

[mlbco]

When did you have Les do your zokes? He told me that he found out he needed to change things from his early 2011 works. Mine that he did, maybe the frist 2011 forks, came back with almost no rebound adjustment. I sent them back and tested the new stuff last friday before changing any of the default settings, I think that they broke (ok re-broke) my left wrist. I dialed in a lot more rebound damping and that helped a lot and changed the rat-a-tat-tat to more of a thud-thud-thud. waiting to get x-rays back before trying it again. but at least now there is some rebound adjustment, there wasn't much before.

Mine were re-valved by LTR in mid April 2011. Did I get the good mod's or the old mod's?

Thanks,

Steve

 

[rgranger]

Mine were done in feb 2011. If you dial in full compression do you see a big difference in rebound? Mine did not, now they do.

 

[mlbco]

I did an extensive set of tests on my '11 300 6 days this weekend adjusting all the clickers and what I settled on is this:

Forks
Comp = 20 open
rebound = 20 open (max)

Shock
Hcomp = 2 open
Lcomp = 20 open
rebound = 20 open
static sag = 32mm

These settings are nearly full 'soft' on all adjustments. The bike can finally handle the rough rocks and closely spaced whoops without destroying my lower back. The downside is that the bike's steering changes characteristics a fair amount because the front and back aren't really balanced and sometimes the front is diving or the rear is squatting. It also doesn't like the bigger jumps at these soft settings. It is easier to ride overall than any stiffer setting.

I'm convinced that another re-valve of both ends of the bike is in order, there is something definitely wrong with the stock Ohlin shock (IMO). The LTR re-valved forks might have been OK if the shock was working properly, but at this point I'm willing to have everything changed. I can already feel my bank account shrinking!

Steve

 

[gassi]

There have been a couple issues with the ohlins shock's, even in very low hour bike's.
I know one almost new '11 SD which have problems with the ohlins shock and it find out, that the gas pressure of the shock was too low. But usually you notice that if you did't feel significant "click" when you turn a reboud adjuster knob, but maybe this is not the case at this time.

One issue is typical if you riding the bike in the winter. It's been speculated that in the shocks fluid chamber there will build up the moisture, the result of the temperature chages and if the bike is been keep in the frozen temperatures, the result will be ice on the inner surfice of the fluid chamber and after that the piston which separete the fluid and the gas in the shock, won't move freely when you start riding next time and if the piston didn't move straight
it can cause the scratches in the inner surface of the fluid chamber and then the gas can go past to the piston and mixing with the fluid and the result is that the shock feels much like the pogostick.
You probably don't see the scratches in the chambers inner surface if you don't clean very well all the oil away from it.

Some issue with the ohlins shock (at least with the couple years older shocks) is that if you have revalved, very loose compression shimstack, it can worn out the shocks mainpiston surface, which is facing to the compression shimstack and the result is the lost compression damping.
What I'm heard from suspension tuners, is that the ohlins shocks have poor quality damping pistons. They didn't have coating in the piston surface, like most of the shocks.

But in that your case, it's probably best thing to do, to send the shock to the service to check out that everything is ok in the shock (enough the fluid and check the properly gas pressure) And if everything is ok, only after that you might think the revalve the shock.

What I'm trying to say, is that even in the new bike's shock there can be something wrong sometimes.

I hope you understand me. My english is not so good...