Hi/Low rebound"??

Eric82930

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Oct 26, 2001
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I would like to start a discussion about rebound. I know the rebound valve stack looks similar to a compression stack in shape but does it have low and hi speed charicteristics? Also if a shock spring is fully compressed is the rebound shaft speed higher than if it only is compressed half way?

Lets start with this for now then I want to talk about the affects of llinkage ratio's and riding styles.
 

russ17

Member
Aug 27, 2002
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Eric absolutey to no.1 I would say yes to no 2 your spring builds up more energy the farther it compresses thats why you have rebound to slow up that stored up energy in the spring .
 

marcusgunby

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Jan 9, 2000
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I feel the rebound stack is overlooked in alot of shocks-a great increase in traction can be gained by making a shock more active-std shocks i have rode are way overdamped in HSR and LSR.

On the question of shaft speed-i would guess the speed if plotted on a graph would be a degressive curve.ie starts rebound at the end of the stroke very fast speeds then slowing progressively down-did that make sence??
 
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russ17

Member
Aug 27, 2002
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I agree marcus that the stock shocks are over dampened. but wouldn't it deppened on the application.I basically just do my own bikes ( woods set ups) fortunatley been able to look at some friends bikes just to see what the other manufactures do with there bikes. back to my question take SX I watch those guys bikes going off jumps and you can actually see the rear just slow down.So IMO I would think in that type application that those guys are running alot of rebound dampening. Just trying to learn

russ17
 

marcusgunby

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Jan 9, 2000
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Russ 100% yes application dependant, i only do mx so thats where i work towards good settings-on rough local tracks we need alot less rebound damping than all the bikes come with from the factory.Trouble is the factorys seem to be trying to make all our bikes for a select few riders-pro sx.
 

Jeremy Wilkey

Owner, MX-Tech
Jan 28, 2000
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Originally posted by marcusgunby
we need alot less rebound damping than all the bikes come with from the factory.

You do! :p

By and large Marcus, I'm with 100%, but we've been looking at more rebound in the forks on lots of bikes.. Rebound is a intresting topic, I have to go pick up my brother Eric at the Airport, and then go out of town this weekend, I'll be back sunday, hopefully I can say more then.


BR,
Jer
 

Eric82930

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Oct 26, 2001
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I don't do motocross so I would'nt care If I am able to seat bounce a jump or not. I ride dessert and I also do prety sick hill climbs where I am some what dissatisfied with my rebound settings but I don't know enough about it to understand what is wrong. My CRF is alot softer than most so I am getting into the stroke pretty far on a regular basis and It feels like it rebounds to fast when its compressed that far. But When I turn in the adjuster It starts to feel dead like its packing. I know the honda has a very progressive linkage ratio and was wondering if this could be confusing my feelings on the rebound.
 

shaggy829

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May 28, 2001
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eric
try balancing out the rebound stack in your crf . honda is out to lunch wuth the the current set up.
shaggy
shaggy
 

Eric82930

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Oct 26, 2001
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Jeremy did the suspension with low flow pistons which work great but I don't know if he did anything to the rebound. I guess he'll tell us when he gets back. I run the rebound at 6 out is the best I can get it. My guess is that it needs more high speed rebound but the same or less low speed. The only time it seems to fast is when it returns from deep in the travel. I know when I climb sick hills I have half the travel used up just from acceleration/weight transfer and when I hit rock ledges It really seems to rebound fast. I could be way off base here. I wish I could feel the symtoms better but its really hard for me to know for shure. I need someone to video tape while I ride through a whoop section.

On another topic It seems from my experience that four strokes hook up way better than two strokes and would require different compression and rebound settings for the shock. If a two stroke packs durring accel. and starts to spin in the chop its all over, but a thumper could get away with it in some cases.

Thanks for the good discussion.
 

russ17

Member
Aug 27, 2002
301
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Eric do you notice it the most when you hit some thing with the front tire under excelleration, it feels real quick like the forks are jumping back at you or the forks what i call or feel like there topping out. Well gotta wait till monday heading for Crawfordsville Ind. Gncc
 
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KTM-Lew

Member
Jan 26, 2002
428
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I'm gonna take a stab at this... :yeehaw:

First I'm assuming you have the correct springs/sag settings for your weight?
I would try backing the rebound back out to a reasonable number like 10-12 and go in 4-6 clicks on the compression. I'm thinking since you say it's hanging down in the stroke more than you like, more comp will help hold it up, and less rebound will reduce the packing sensation. :think: Maybe not the optimal set-up but will give Jer something to go on. Of course you have to be careful when adjusting reb as the bike tends to get evil real quick when you back it out too far.

I prefer for woods to run on the soft side spring wise and then use the comp clickers to reduce pitching for and aft.

Remember clickers are low-speed/free-bleed only and rebound has an effect on comp. When testing a new set-up I pick a familiar section of trail and ride at about 60-70% speed until I get things close. I go 2-4 clicks at a time until I find the limit (too stiff) on comp or too twitchy (rebound out too far). I start with the comp and find the middle ground and then do the rebound. Then I pick-up the pace and go 2 clicks which-ever way I feel it needs. Now I'm ready to take some notes and decide whether to go in or out a click or 2. Don't be afraid to adjust. Take notes. Don't go all out until you know what the bike is gonna do. :thumb:

Good Luck
 

Eric82930

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Oct 26, 2001
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Russ
The rebound I am worried about is the shock not the fork. The shock does top out though and usually leaves the ground (Major traction problem when hill climbing) At this point I feel the fork is super and can't fault it for anything. I know the feeling you described and I think Iv'e got it dialed just right.

Ktmlew,
The spring rate was tested for my weight and I have tried different sag settings with 90mm being my preference. I have also tried more compression damping (it definately keeps me up higher in the tarvel be the rebound still seems to fast.) I don't mind the fact that it uses more travel than most if I could resolve the rebound issue. In fact I specificly requested soft settings for woods/rocks. I'm a short guy and I beleive a bike needs to use most of its travel under extreame impacts (for what its setup for) otherwise theres no point in having that much travel which makes the bike taller. I came off a klx300 which only had 11" of travel when most bikes had 12+. I used it all regularly but did not ever have the rear rebound like this.

Thanks for all the help and discussion. Iv'e been studying this group for along time and really feel it has been an excellent tool to help me know how I want my suspension to work and what I feel needs improving which is a very important step that many people miss. It must make suspension shops jobs that much harder when a customer doesn't know what they want.

My conclusion at this point is that stiffer compression is not an option since I have had it valved stiffer before and it slows me down in the type of riding I do. I don't want to waste the last 4" of travel just because it rebounds to fast when it uses that much travel. (opinions welcome here). I would like to know more about the possibilities to control the rebound without adverse effects. More technical stuff like hi/low speed affects on packing etc..

Thanks again.....
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
Eric to me it seemd like you do need a little more HSR as you are compensating for this with the clicker.I have a similar set up to you-low flow pistons and i know the sensation you speak of concerning the rebound.It can work well to increase traction but if you are not confidant and dont like the fast rebound feel then im sure mx tech will dial it in to your needs.You are 100% correct about tuners having a hard time understanding the needs to the buyer-most people know what they like/dislike but find it very hard to put into words-abit like visiting your doc-we dont talk the same language so things are easy to miss.
 

Jeremy Wilkey

Owner, MX-Tech
Jan 28, 2000
1,453
0
Guys well put. I often advise riders to add compression when they have suttle rebound issues, however thats not an option most of the time for offroad riders unless they are doing deep whoops.

It becomes very important to think about whether your dealing with reaction of the problem, or the problem, many times people confuse the two. As for comunicationg with a tuner, a good tuner never ask you what the problem is and never makes adjustments in that manner. A good tuner ask what the bike is doing and where, and then they reconstruct the forces acting on the suspension and build the case backwards, it makes things way easier, when it becomes dificult is when a rider only, complaines, or tryes to do our job for us, and that often results in improper diagnosis. I can think of a few recent examples, and generaly if I can't fix a rider in two tries at bat, I don't go to the palte for a third, its a waste of time.

Eric,
Please if you have any issues drop me a line brother, I'll will do my best to get you waht you need.


As for the rebound topics, rebound is a intresting topic, in generall it has a somewhat self correcting tendency and as a spring traps more energy and as a result generates more restiastance from the spring. The real trick is seting things up lose enough for good traction yet slow enough for control.

Its allso intresting that performance is clearly improved with settings that riders deem fast, yet allmost allways that fact is ignored. It seems making the rider more comfortable makes the results better no matter what performance should dictate.

Ok, I still have more to say, but my brain is sore, I'm going to give this till to tonight maybe I will be able to rein in my scatred thoughts on this topic. We need to talk about the effects of single and dual rebound, preloaded rebound, and bleed.. Those are some very important by lines to this whole topic.

Br,
Jer
 

Eric82930

~SPONSOR~
Oct 26, 2001
76
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Thanks for all the good info,
I talked with Jeremy and I am going to have him add more high speed rebound on the shock. It may be a few weeks but I'll let you know the results.
 

russ17

Member
Aug 27, 2002
301
0
 

russ17

Member
Aug 27, 2002
301
0
sorry guys I guess I dont have this quote thing down. I dont no how that the whole page got on there .I saw Jer was on just thought he might keep this rebound topic going



thanks russ
 
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