rebound is riders speed dependable?

[georgieboy]

Most people are talking about the compression side of suspension, but i like to know some more about rebound.
I understand, doing all the reading here, that the faster a rider becomes the lesser rebound you need. But rebound is also very important in the cornering of a bike. So when you speed up the rebound for the straight line effect you screwing up the cornering of that same bike. Am i right on this?

 

[marcusgunby]

You are but your not;) some very fast riders like very little rebound damping but thats because they push so hard into turns that the front will pack and knife under.Most mortals dont like/need this type of setup.

 

[Luft]

Rebound damping controls the rate at which the compressed spring returns to its precompressed position. I've backed out the compression and rebound damping all the way on both ends on my 03 RM 125. Keeping the bike stationary and pushing down on the suspension you can feel the suspension returning to its starting position. I've been riding on very flat ground with a minimum of obstacles, except small jumps, and really like the way the bikes responds. Before, I would follow the manual settings and found they did not work for me at all. I run .46 and 5.5 springs with stock valving.

 

[marcusgunby]

WOW Luft that adds up to some fast returning of the forks with those spring rates, make sure youa re carefull if you visit a mx track.

 

[Luft]

Yes, I will definitely take it easy. I weigh 230 lbs., so those springs have alot of work to do. I will be riding at what they call an easy supercross track. It's been a few years but I'll manage to have fun somehow.

 

[mxneagle]

Actually the faster you go the slower rebound you need. Why? to help keep the bike lower over jumps so you need to hit them faster to clear. Since they are only hitting the tops of most of the bumps the need to "reload" the suspension for the next bump is minimized.

 

[georgieboy]

mxneagle, that is a different angle of looking to it. You won't compress as yr skimming the tops of the rough.
And Marcus, i was thinking about that the minute i wrote down the topic. When your driving harder you probably corner harder so the forks and shocks will lower anyway to the right setting. And will stay there because of the cornering.
Can you also give me a clue at what piston speed shims bend?
I did a search but cldnt find anything. Thnks in adv.

 

[ruddycooter]

i think the shims bend at all speeds. It just depends on how fast its moving. I got this from reading at www.shimprogram.com

 

[Luft]

here's a link on shim bending
http://www.mx-tech.com/articleread.asp?ArticleID=23
there are three articles

 

[russ17]

mxneagle


In all actuallity most of the pros that I know run really fast rebounds(depending on the application) as far as staying low I am not saying the rebound does not have an effect but the riders technique plays a very important role here. Take a look at Steward, Reed, Big daddy MC,RC

 

[Luft]

Check out Eric's article Video Suspension tuning, it has info about shim bending. Thinner shims bend at lower compression speeds and thicker shims bend at higher compression speeds.

 

[Jeremy Wilkey]

Guys something very important to consider is that rebound is only the outcome of the compression..I think thats why in many ways its left out of consideration by so many..

But thats a good thing, many of the "stay low and so forth" is tuned by rebound when in reality its best tuned by compression.. Think of it as treating a cause rather treating a symptom..

Most riders MASSIVELY overly tighten rebound settings.. I always suggest you run it as lose as you can tolerate, you'll get more drive if your on the gas, and the faster yuor going the more likely that is..

Paul Thede really pushes this point with his intersection of two induvidual slopes, one equals perception of control the other traction. More rebound builds perception of control, but is inversly related to traction....and with less traction you really have less control...

I really enjoy the whole topic of rebound, and its an area where I think its easy to make bikes better right away.. Just look at the Stock CRF as an example.

BR,
Jer

 

[JTT]

Good to have you back Jer! :thumb:

Originally posted by Jeremy Wilkey
Just look at the Stock CRF as an example.

Could you please elaborate on this Jer? I have not kept up on the development of the CFR. Are you saying they lightened the rebound?

 

[Jeremy Wilkey]

JTT,
They actually made the low speed really soft and the high speed equallly as stif.. Its very hard to control between kicking andf packing.. A very old school set-up..




BR,
Jer

 

[TVRider]

So Jeremy, I understand what your saying about compression. How would you set rebound?

I'm a real novice at this suspension stuff, but riding this weekend I took my 98 GasGas Trials bike and my KDX200 with KX front end. There was one particular section that had softball to bowling ball size rocks strewn all over the hill going up out of a creek. It also had a couple low ledges (6'' - 12"). On the trials bike I could just blast up, total control. On the KDX the back end was kicking everywhere and it was tough to get up. I'm tempted to lower my spring tension and compression setting on the rear shock, but what about the rebound? By the way most of our riding is tight slow stuff so high speed stability is not a huge issue.

Tom

 

[mxneagle]

Different setups are required for different types of riding (IE SX, MX, HS...) so it's important to realize the specific requirements and speeds of what you do. For example, a very plush setup with a rather soft "high speed" compression and light rebound is the ticket for Hare Scrambles where your running over logs, rocks, rain ruts etc... but I wouldn't recommend it on your average MX track.
You must also consider rider ability, If you are capable of hitting all the jumps perfectly and landing on the down side you'll want a different setup than the guy who's comming up short or overjumping the doubles.

 

[JTT]

TV, if you set up your KDX like your trials bike you would be bottoming alot. Trials bikes are set up VERY light on compression and even lighter on rebound. This is what gives them that "bouncy" or "lively" feeling. That said, they also have limited travel compared to your KDX (roughly 8"vs12")

That extreme soft, and springy suspension, combined with bubblegum tires is what allows the bike to soak up those bowling ball size rocks. At greater speeds that same characteristic will have you bottoming harshly and getting bounced out of your seat on bigger hits. mxeagle makes a good point that there are setups for different types of riding and types of bikes and they don't always overlap well.

That said, try going softer on your KDX. I like to make large changes and then fine tune backward. It allows you to really feel the difference in a dramatic way. Try backing off the compression 5-8 clicks as well as the rebound. Take care though as big changes make for big effects.

 

[georgieboy]

I have been shuffling the shims a lot lately and came up with more rebound on mine marzocchies. They were so plush on comp and rebound that they were very lively but when i was hitting edges etc hard, too lively i realised. So i stiffened up the rebound and found it was easier on the rough when i was speeding it. I did noticed when i was diving in a sandy corner that is was knifing in a bit, but that cld also come because i must keep the speed up thru the corners. Or stay back on the bike a bit more. Here in holland we have real sand, the sand u wld not come out of when you slow it down too much.
So i wld say it is a tricky business setting up yr rebound, much more then the comp side, where you just need enough bottom resistance and a plush riding feel.

 

[DEANSFASTWAY]

Too much rebound and youre Packing . Its way harder to control a bike with a rear wheel that doesnt follow the ground . If you think of it as a wave out on the sea .wqith each wave there is a rise and fall and with each fall if you cant come back up youll find yourself going under. As Jer stated there is a graph for compression and rebound of a particular event and in the middle of that graph is control or traction . To be properly balanced youll want to be right on or above that average line. If a suspension is too soft it will compress too far and have to overreact to control the energy stored then you might think of turning in the rebound stiffer for good measure . NOT! what you really need is a bit more comp/damp to lessen the rate of depression from the bump. If you hit a section of whoops with a soft comp slow rebound rear after like the third or fourth bump event the suspension will ride lower and lower . The suspension will not be reactive enough to return or release that energy.Slow rebound on turns will not let the front end plant or set up forturns and not transfer weight to front end as easily and bike may feel dead . Slower riders usually seem to like more rebound, it gives them a sense of security probably. Like Georgieboy states you need a good reactive suspension in sand espescially long sets of sand whoops. Here in Jersey we have a very diverse terrain composition . A Hare Scramble or Enduro may have rutted rocky rooted sections under trees ormiles of Beach like sand whoops. its very hard to setup for so we usually pick something versatile. Its usually better to setup a bit more for the rough stuff than make it real plush for the rocks and roots and if youre going to have a getoff you wouldnt want it to happen on the high speed nasty stuff that where youll end up with a plaster trophy .

 

[georgieboy]

Deans, i was merely talking about the marzocchies in the front as the back comes with a sachs as you will know.
Now that i have revalved both ends i am very happy with the way things have turned out.
The sachs shock now really come s with faster rebound, and that have really improved my cornering. It just seems that the bike is willing to turn by itself. The only thing i have to do is turning the throttle once on the apex.
The zocchies were without rebound (sort of) and i made a valve stack that allowed me to turn the rebound to satisfactory with the clickers. The front is now less nervous tru nasty stuff. So here more rebound did the trick.
Also during cornering i feel that the fronts bites better cause of the more rebound.
Still i have to go to a crosstrack and see how things work with jumping but right now i am very happy.
By the way, i closed all the bleeding holes in the comp-cartridge and have a better progressive compression all the way tru the stroke.
I made the bottomvalve with a freebleed of 0.1mm and i might do there some more fiddling. Right now i feel i did a nice job. Thnks to you guys.