How do you fix Rear Suspension "bounce" ?

[Wannabe_4x4]

Glad to report I lost a little weight... down to 300 from 335. woo hoo! I should celebrate with a cake. just kidding!

To update: I have the Penske 8983 adjustable rear shock.

My suspension was "okay" I guess before, but now I'm getting this:

In a long sweeper turn, there's a mild rolling bump/hump then a small dip right in the middle of the turn. I feel the impact of the initial bump (rear end comes up a little), drops down, then I bounce 2/3 times before the bike settles.

Do you think it's:

1. too much compression dampening? (meaning the piston inside the shock isn't moving fast enough upwards allowing the rear wheel to absorb the bump).

2. not enough rebound dampening? (meaning the piston shoots out too fast causing the bounce/pogo action)

3. a combination of all the above?

By the way, the front end feels great... absorbs the ripples in the pavement, doesn't fall in or shoot up too fast.

 

[fjrrider]

Suspension settings , man o man, maybe the most complex subject on this board.

Sounds like you have a general idea about. What I would reccommend is going back to stock settings (not just the shock but forks too) You got yourself a little test section, ride it over and over, making adjustments after each pass. When you get it where you think its really good, write down the setting then go check stock settings again.

Have you set the sag? You lost a lotta weight, thats affected by 35 lbs for sure!

 

[Bungie]

Rebound damping. Unless that first bump just about launches you off the bike.

 

[UberKul]

Rebound damping. Unless that first bump just about launches you off the bike.

That would be my guess also, if you are bouncing I would go a few clicks more on your compression as well. Pretty hard to tune your bike to absorb a roller unless you have high and low speed compression adjustments.

Just my 2 cents.

 

[FJRless]

I suggest not tuning suspension for one strip of road. If the susp is working great otherwise then it probably needs nothing. Sag should be checked nonetheless to make sure you have proper preload on the spring. If these issues are a theme and your preload is right then you can slow the suspension by adding damping, compression and reb.

 

[bikerskier]

Call the experts at GP Suspension in Oregon City!

 

[Jagermeister]

No one's asked so I will:

How many miles on that Penske? They do require a rebuild from time to time.

 

[HaulinAshe]

No one's asked so I will:
How many miles on that Penske? They do require a rebuild from time to time.

It's an '09. Not much chance he's worn the seals yet.

He's in search of suspension nervana. Worthy goal, perhaps not achievable, but no worse than many other pursuits in life.



Assuming all mechanical pieces are in good working order, suspension tuning goes like this. (Everybody sing along now!)

SPRING

REBOUND

COMPRESSION

Spring rate, spring preload, Rider Sag, Free Sag. If his SPRING numbers/measurements are good, REBOUND is next.

Opening up Low Speed Compression before evaluating Rebound is a good technique for fine-tuning. Just make damn sure you know where LS Compression is supposed to return to.

 

[Wannabe_4x4]

suspension nervana.

man o man... I'm almost there. oye. turns out it was TOO MUCH rebound dampening. The rear shock was packing in, so the first bump forced the rear wheel up, but it didn't return fast enough, so when I went into the dip, there was no where for the rear wheel to go anymore, and so it felt like a bounce.

I did notice that when I took out 2 psi in the rear tire, feeling the little cracks and ripples in the pavement went away.

I know I'm going to get hell for running 40 psi front and rear, but it's the only way to get the suspension nearly perfectly smooth. If I opened up the compression dampening, the bike squated too much in the rear, and totaly threw off everything else. Even GP in oregon and traxxion dynamics back east say that 42 psi is TOO MUCH air.

 

[Wannabe_4x4]

So here are my numbers as of 9pm, 2/18/10

fork compression 12

fork rebound 10

fork sag 45mm

front tire psi 40

rear compression 12

rear rebound 20

rear sag 35mm

rear tire pressure 40

 

[RadioHowie]

So here are my numbers as of 9pm, 2/18/10
fork compression 12

fork rebound 10

fork sag 45mm

front tire psi 40

rear compression 12

rear rebound 20

rear sag 35mm

rear tire pressure 40

What were your numbers at of 9:02pm???? :rofl:

 

[3dogs]

You can check rebound damping to see if it’s in the ball park without actually riding your bike. The procedure is the same for front and rear suspension. Here’s how:

1. Get a helper to hold the bike up. You will be bouncing the suspension and need both hands free.

2. Bounce the rear of the bike by pushing on the rear of the seat (handle bars on the front)

3. Watch the action of the suspension as it rebounds after you pushed down on it.

4. Ideally, rebound settings should allow the rear suspension to return to the top of its stroke/travel as fast as possible without any additional bouncing (a slight bounce is OK).

5. To determine where you rebound setting is at turn the adjuster so you have little, or no rebound—now bounce the suspension.

6. Watch how may bounces the suspension goes through after it reaches the top of its travel. Increase the rebound setting until the suspension rises as quickly as possible and DOES NOT take a secondary bounce.

You will have to make an adjustment past the point of too much rebound, then back it off to see where the ideal return rate is.

By bouncing, adjusting and observing you can get a good idea where to set rebound damping. Once you have reached the ideal setting (step 6) go for a ride for further suspension tuning.

At this point what you feel and how you evaluate how effective your rebound setting are is highly subjective. I have found over the years of doing this in Total Control classes that step 6 is good enough for 90% of riders.

One last thought. Make sure that you ride on a road that actually has bumps/dips for suspension evaluation. Too many riders find a perfectly smooth road and come to the erroneous conclusion that their suspension is working great.

Total Control Advanced Riding Clinic classes have a suspension section (lasts about a hour). See the Schedule for classes near you.

 

[Bounce]

[Zzzzzz]

[Hrgrmph]

Bounce bounce bounce?

Did someone call? I'm trying to sleep over here.

 

[Wannabe_4x4]

You can check rebound damping to see if it’s in the ball park without actually riding your bike. The procedure is the same for front and rear suspension. Here’s how:
1. Get a helper to hold the bike up. You will be bouncing the suspension and need both hands free.

2. Bounce the rear of the bike by pushing on the rear of the seat (handle bars on the front)

3. Watch the action of the suspension as it rebounds after you pushed down on it.

4. Ideally, rebound settings should allow the rear suspension to return to the top of its stroke/travel as fast as possible without any additional bouncing (a slight bounce is OK).

5. To determine where you rebound setting is at turn the adjuster so you have little, or no rebound—now bounce the suspension.

6. Watch how may bounces the suspension goes through after it reaches the top of its travel. Increase the rebound setting until the suspension rises as quickly as possible and DOES NOT take a secondary bounce.

You will have to make an adjustment past the point of too much rebound, then back it off to see where the ideal return rate is.

By bouncing, adjusting and observing you can get a good idea where to set rebound damping. Once you have reached the ideal setting (step 6) go for a ride for further suspension tuning.

At this point what you feel and how you evaluate how effective your rebound setting are is highly subjective. I have found over the years of doing this in Total Control classes that step 6 is good enough for 90% of riders.

One last thought. Make sure that you ride on a road that actually has bumps/dips for suspension evaluation. Too many riders find a perfectly smooth road and come to the erroneous conclusion that their suspension is working great.

Total Control Advanced Riding Clinic classes have a suspension section (lasts about a hour). See the Schedule for classes near you.

This is beyond funny, and ridiculous. when i open up the rebound, I definitely get more bouncyness. If I close/tighten the rebound dampening, the back gets stiff and the bumps are more harder. If I open the compression, the rear of the bike sags more to where it'll bottom out almost. If I tighten the compression, the ride gets more harsh and stiff and I can feel more of the bumps/cracks/ripples on the road.

I lowered tire pressure to 40 psi in the back, and that helps, but still can't get rid of the bumpiness.

Tried the zip tie method.. in some cases using 3" of the suspension travel in the back over a rolling bump followed by a rolling smooth dip, in others only using 1" of travel over ripples and cracks.

Is 38 psi the way to go?

Open the compression AND open the rebound = pogo central... more bounciness.

tighten compression and open rebound = harsher ride, more bumpiness

open compression and tighten rebound = packing in the back, more bumpiness

tighten compression and tighten rebound = stiff city... very bumpy

 

[FJRless]

The first thing you have to do is set the preload. Measure sag and determine if preload is correct. Once you've done that, then you can adjust the compression and rebound damping. This isn't rocket science.

 

[HaulinAshe]

You are not allowed to skip Step-1, SPRING.

Your settings are meaningless without rider weight, spring rate, rider/static sag, free sag information.

Let me sing again....

SPRING

REBOUND

COMPRESSION

SPRING

REBOUND

COMPRESSION

I can be very annoying.

 

[Wannabe_4x4]

40 and 42 psi.. that's what gets me. when i run that much air pressure, i get the bumpiness on the cracks and ripples. if i go down to 40 in the back, no ripples.

figured out the initial hard hit was because my spring tension was too loose. I gave the rear shock 2 full turns of pre load, and now that hard initial hit is all but gone. the subsequent dip mildly pogos now, but not like it was doing before.

I'm happy, for now. gotta wait a couple days till the spring settles again with the extra preload dialed in, then i'll report back.

 

[Wannabe_4x4]

:yahoo: I've done it! I hit suspension Nirvana!!!!!! It's like that guy in Waterworld saying he's seen dry land! lol. 7 months of maticulous recording data, tweaking and turning. Happy to report I'm back in "Club 42" as well... 42 psi in the rear tire.

Thank you ALL for the feedback, tips and pot shots. Actually a combination of what everyone was saying applied to my suspension woes. Luckily now after all is said and done, my bike truly feels like it's riding on rails. Grips the road extremely well, and cruised at 65 mph through a tight 35mph sweeper this morning. :clapping:

So here are the final #'s.

I'm a 300 lb. rider with gear on.

Using Michellin Pilot Road tires... not the 2C... just the regular Pilot Road ones.

Complete suspension buildup assembled by Peak Performance in Simi Valley using GP Suspension parts. Running a Penske 8983 adjustable rear shock (valved and set up by GP), and .97 springs upfront with new valves from GP Suspension in Oregon.

Front Fork:

Compression Dampening - 12

Rebound Dampening - 12

Preload - Zero lines showing... nut is flush with the cover (only the hex pattern is above the cover)- amounts to 48mm of sag while I'm sitting on the bike

Front tire pressure - 40 psi at 6:00 AM measured in a 60 degree F. garage

Rear shock

Compression - 13

Rebound - 22

Preload - hard to say, but added about 4 or so full turns from what GP set it at - amounts to 35mm of sag while sitting on the bike. When I was setting this, it was a matter of hitting tight sweepers at speeds of 40-60 mph. If I felt like my body weight was on my wrists, I backed off a half turn on the preload till the bike felt level under the g forces of the turn. When the bike felt lower and squatting in the back, I turned the pre load 1/2 turn tighter till it felt level again.

Rear tire pressure - 42 psi at 6:00 AM measured in a 60 degree F. garage

Like Ashe says... gotta do the SAG first! Without that, I was messing with the compression and rebound, when it turns out all I had to do was add a turn or two of preload.

 

[boomerang]

I think the key to your problem lays in you first statment,you said you lost wieght.

Soften compression.

Tighten rebound.

But then again are you sure that you are not already about bottomed out?

If thats the case,I would think you need to increase compression. Then possibly reduce rebound rate.