Seat bounce

Hank_Thrill
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6/11/2020 8:05pm
abn166 wrote:
I can't believe someone like Ricky still believes seat bouncing causes the shock to work like a pogo (his words) and send the bike and rider...
I can't believe someone like Ricky still believes seat bouncing causes the shock to work like a pogo (his words) and send the bike and rider higher and farther. The dampening in the shock would not allow for that. Here is a photo from RacerX of Tomac seat bouning a jump. The rear of his bike appears to be more compressed because of seat bouncing. TFS where are you?
Here’s my take on it. Ralph made the comment first and RC piggybacked off it. I think Ralph even asked RC a question.

Regardless, how professional would it have been, and how confused would non-moot viewers been if RC said, “We’ll Ralph, actually.... before proceeding into a five paragraph TFS/Vital essay.”
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Forty
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6/11/2020 8:06pm
seth505 wrote:
Force...potential energy. There is more at play than the rear shock. Shove the bike into the face of the jump so the suspension collapses, the frame...
Force...potential energy. There is more at play than the rear shock. Shove the bike into the face of the jump so the suspension collapses, the frame and chassis parts flex extra hard...That causes a reaction that will absolutely boot you up on a higher trajectory.

How do people think you can pump a bicycle when it has no shocks and no motor, yet you can pick up speed without pedaling?
Yes! Energy. Just cause you can’t see it doesn’t mean it’s not there.

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seth505
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6/11/2020 8:08pm
SoCalMX70 wrote:
"How do people think you can pump a bicycle when it has no shocks and no motor, yet you can pick up speed without pedaling?" With...
"How do people think you can pump a bicycle when it has no shocks and no motor, yet you can pick up speed without pedaling?"

With the momentum generated by the rider's body movements in conjunction with the rollers on the pump track. How do you swing on a swing?

Different concepts I'd say, but I'm loving the debate.
As I typed that I realized I went off on a tangent but ya, you get it. Jump trajectory definitely a different case than a bicycle speeding up or slowing down due to different input
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6/11/2020 8:08pm Edited Date/Time 6/11/2020 8:11pm
Since we're arguing semantics, if a seat bounce doesn't actually bounce you, what shall we call it then?

Butt boost?
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The Shop

Hank_Thrill
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6/11/2020 8:13pm
SoCalMX70 wrote:
It's just changing the angle of the bike (the trajectory) at take off. Makes it "steeper". That's it. There is no bounce/spring upward effect. Thank you...
It's just changing the angle of the bike (the trajectory) at take off. Makes it "steeper". That's it.

There is no bounce/spring upward effect.

Thank you TFS.
Exactly,

Pulling up on the handlebars on a dirt bike is fruitless, in comparison to a pulling up on the bars of a bicycle. Seat bouncing is in essence a Motocross technique to get the bike trajectory going upward at a steeper angle (eg., 45 degree trajectory as opposed to 35 degrees).
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6/11/2020 8:21pm
davis224 wrote:
And we're off! How can the shock pogo you up when it has damping? Why don't you bounce when you land from a jump? How does...
And we're off!

How can the shock pogo you up when it has damping? Why don't you bounce when you land from a jump? How does it spring you higher when it doesn't even extend until after you've left the ramp?

You're changing your trajectory. Not literally bouncing.
Exactly.

By sitting with hard throttle and increased traction which compresses the rear of the bike more,, you actually aim the front of the bike higher and this makes a steeper angle of attack off the face of the jump.

You go higher and further.
6/11/2020 8:31pm
Also...you can do the same thing on perfectly flat ground. Go along at a steady speed. Accelerate hard, weight the back of the bike, then chop the throttle as you move up and forward. Done with correct timing your bike will actually leave the ground. You can prove it by doing it on unmarked ground.

Gary Bailey showed us how to do this in the 80's. It does work.
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Crush
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6/11/2020 9:33pm
It doesn't rebound? Well it fucking does something, because people use it when they're going slow and can clear obstacles they normally wouldn't at the same speed standing up.

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sumdood
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6/11/2020 10:33pm Edited Date/Time 6/11/2020 10:35pm
My son tried to teach me how to do it one time. It hurt.

Not sure how some of you guys are convinced there's no "rebound" action helping the bike go higher. It might not be a lot but it's some. It has to be more than if the suspension was soaking it up ? When the shock gets pre-loaded by bouncing on the seat it compresses and goes into the stiffer part of the travel, less "soaking up" means more "pushing off" Simple physics. It has too. Plus why would guys who can do it call it a seat bounce if the bike didn't bounce ? They don't call it "Pre-load assisted take off angle adjustment" Laughing
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FIREfish148
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6/11/2020 11:48pm Edited Date/Time 6/11/2020 11:55pm
How many people here have actually ever seat bounced anything?

Anyone that wants a science lesson from Ricky, or any other rider (for the most part), on the exact science behind seat bouncing is gonna have to realize he isn’t the greatest of all time. We need to ask James Stewart.
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6/12/2020 12:46am
I’m starting to think a lot of the people on this forum don’t even ride...
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dantking
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6/12/2020 1:27am

it is not seat bounce that makes the difference. It is the hard acceleration up of the jump with all the weight on the rear wheel it makes the shock absorber collapse completely before leaving the jump and all the energy from the jump turns into airtime / distance. if you don't seat bounce but jump normally you won't comprese your suspension as much and it will absorb energy all the way up the jump

English is not my first language Smile
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davis224
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6/12/2020 2:42am
Crush wrote:
It doesn't rebound? Well it fucking does something, because people use it when they're going slow and can clear obstacles they normally wouldn't at the same...
It doesn't rebound? Well it fucking does something, because people use it when they're going slow and can clear obstacles they normally wouldn't at the same speed standing up.

It does rebound, but not until you've already left the ramp. Say if you weren't on the gas hard enough to keep the shock from rebounding, you would endo, because the gentle push from a dampened shock rebound would turn that momentum into the bike rotating slowly nose down, not launching the 400lb of man and machine several feet higher in the air. Your trajectory and momentum changed. You didn't bounce, even if that's what we call it because that's what the sensation is.
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motoman154__
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6/12/2020 2:58am Edited Date/Time 6/12/2020 2:59am
If you were to jump on a trampoline but you could bring the trampoline back upwards with you, both you and the trampoline would launch upwards as your energy rebounds. A seat bounce is the same thing. After compressing the shock extra hard on the face of the jump (these pros aren’t just sitting down, they’re actively pushing the bike down), the rider feels the exact same force upwards after take-off — launching him up. By pulling the bike upwards with him, the bike goes higher than it would have with no suspension. If a rider seat-bounced something and let go immediately after take-off, he would go flying upwards, taking a drastically different trajectory than the bike.

Edit: Endos occur when a rider doesn’t bring the bike with him.
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aees
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6/12/2020 2:59am
Jesus, how the fuck can anyone that has ever been on a mx track more than 2 laps says there is no such thing as seat bouncing?

The last things that happens when you leave the jump face is that the shock rebounds faster then normal since you also move the weight from the seat and forward (unless you want to loop out).
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davis224
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6/12/2020 3:39am
If you were to jump on a trampoline but you could bring the trampoline back upwards with you, both you and the trampoline would launch upwards...
If you were to jump on a trampoline but you could bring the trampoline back upwards with you, both you and the trampoline would launch upwards as your energy rebounds. A seat bounce is the same thing. After compressing the shock extra hard on the face of the jump (these pros aren’t just sitting down, they’re actively pushing the bike down), the rider feels the exact same force upwards after take-off — launching him up. By pulling the bike upwards with him, the bike goes higher than it would have with no suspension. If a rider seat-bounced something and let go immediately after take-off, he would go flying upwards, taking a drastically different trajectory than the bike.

Edit: Endos occur when a rider doesn’t bring the bike with him.
Do your trampoline springs have dampened shocks inside of them?
motoman154__
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6/12/2020 3:44am
If you were to jump on a trampoline but you could bring the trampoline back upwards with you, both you and the trampoline would launch upwards...
If you were to jump on a trampoline but you could bring the trampoline back upwards with you, both you and the trampoline would launch upwards as your energy rebounds. A seat bounce is the same thing. After compressing the shock extra hard on the face of the jump (these pros aren’t just sitting down, they’re actively pushing the bike down), the rider feels the exact same force upwards after take-off — launching him up. By pulling the bike upwards with him, the bike goes higher than it would have with no suspension. If a rider seat-bounced something and let go immediately after take-off, he would go flying upwards, taking a drastically different trajectory than the bike.

Edit: Endos occur when a rider doesn’t bring the bike with him.
davis224 wrote:
Do your trampoline springs have dampened shocks inside of them?
The only way that dampening is relevant to this thread is the fact that it keeps you from paying a visit to the ISS if you seat bounce something too hard
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wildbill
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6/12/2020 4:05am
I hit a false neutral once while doing this. Not fun.
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ns503
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6/12/2020 4:06am
Seat bounce talk. Ah the old days.

Lots going on in a seat bounce, but the springs pushing you up isn't one of them. Or it's a negligible part at least.

The only thing you are doing with the springs in any of this, is removing their function from the equation - not using their bounce to add to it. You collapse them, so then they don't have any of their natural capacity to absorb energy left as you hit & run up your take off, so all the upwards take off force can go into your bike and make it go higher. Rather than being absorbed by the springs. Which also has a trajectory changing effect. Get your weight behind it by throwing some body english into it too and away you go, onward & upward. Throw your english the wrong way or not get your forward momentum right (a combo of trajectory & speed) & hello endo.

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6/12/2020 4:07am
Load up that tire and bump rubber to help boost the springs return.
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Andy7
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6/12/2020 5:39am
Have you ever tried jumping the same jump, one time coming with constant speed and the other applying throttle on the face of the jump? Did you notice that If you accelerate at the face of the jump you can even overshoot it? To actually seat bounce, not only are you seating farther back, but also accelerating more. I would say that the shock's compression is a result of this extra throttle you are giving it. On the other hand, seat bouncing acts like a 'catapult' that can make you endo if not done right. As someone else already mentioned, you are actually pulling the bike up with you.
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Mr. Afterbar
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6/12/2020 5:52am
How many people here have actually ever seat bounced anything? Anyone that wants a science lesson from Ricky, or any other rider (for the most part)...
How many people here have actually ever seat bounced anything?

Anyone that wants a science lesson from Ricky, or any other rider (for the most part), on the exact science behind seat bouncing is gonna have to realize he isn’t the greatest of all time. We need to ask James Stewart.
When I’m tired and don’t feel like pulling off when practicing, I seat bounce everything.
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EngIceDave
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6/12/2020 6:29am
A TFS experiment (physical or mental)

If you took your motorcycle and four (4) tiedowns, and compressed your bike's suspension as far as possible, and were able to simultaneously release all four tiedowns, all at once....

Will the bike leap up off the ground several inches, actually getting "air," or would the shocks just rebound the bike to its standard position?
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STLSharky
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6/12/2020 6:32am
davis224 wrote:
Since it was briefly discussed in the 250 main, dare we delve back into one of the greatest motodrive threads ever? No, your shock does not...
Since it was briefly discussed in the 250 main, dare we delve back into one of the greatest motodrive threads ever?

No, your shock does not "bounce" you higher. Discuss.
No matter what our old buddy Steve said it just fucking works, forget the science, it fucking works
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aees
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6/12/2020 6:49am
EngIceDave wrote:
A TFS experiment (physical or mental) If you took your motorcycle and four (4) tiedowns, and compressed your bike's suspension as far as possible, and were...
A TFS experiment (physical or mental)

If you took your motorcycle and four (4) tiedowns, and compressed your bike's suspension as far as possible, and were able to simultaneously release all four tiedowns, all at once....

Will the bike leap up off the ground several inches, actually getting "air," or would the shocks just rebound the bike to its standard position?
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on flat ground.

It is a combination of loading the suspension with body position and throttle, as well as taking weight of the seat just before wheels leave the jump face and lifting the bike a bit since you move fwd in the process.

If seat bounce does not work, neither does scrubbing or absorbing suspension travel with legs since it is the direct opposite of seat bounce.

Two persons going up a jump face all things being equal, one will seat bounce I promise you that bike if going higher then the other.

Extra height is typically what you want when seat bouncing, so you don't run the front wheel to short coming into landing or next jump.
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Momus
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6/12/2020 7:05am Edited Date/Time 6/12/2020 7:07am
FahQ wrote:
I’ll play The tire has no rebound damping, And also if you get down into the bump stop that will over power the rebound of the...
I’ll play
The tire has no rebound damping,
And also if you get down into the bump stop that will over power the rebound of the shock.
Unfortunately I have the video to show it
A tyre has hysteresis. It does have damping to an extent. Ditto a cellasto- polyurethane foam type bump stop.

The primary cause of pneumatic tire rolling resistance is hysteresis:
A characteristic of a deformable material such that the energy of deformation is greater than the energy of recovery
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Momus
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6/12/2020 7:08am
EngIceDave wrote:
A TFS experiment (physical or mental) If you took your motorcycle and four (4) tiedowns, and compressed your bike's suspension as far as possible, and were...
A TFS experiment (physical or mental)

If you took your motorcycle and four (4) tiedowns, and compressed your bike's suspension as far as possible, and were able to simultaneously release all four tiedowns, all at once....

Will the bike leap up off the ground several inches, actually getting "air," or would the shocks just rebound the bike to its standard position?
aees wrote:
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on...
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on flat ground.

It is a combination of loading the suspension with body position and throttle, as well as taking weight of the seat just before wheels leave the jump face and lifting the bike a bit since you move fwd in the process.

If seat bounce does not work, neither does scrubbing or absorbing suspension travel with legs since it is the direct opposite of seat bounce.

Two persons going up a jump face all things being equal, one will seat bounce I promise you that bike if going higher then the other.

Extra height is typically what you want when seat bouncing, so you don't run the front wheel to short coming into landing or next jump.
This ^
EngIceDave
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6/12/2020 7:10am
All you're doing is a combination of things...

You're changing the attack angle
On take off, you're changing body position, creating more forward energy/momentum
You're on the throttle, which is important, because if you chopped the throttle at that point, the forward momentum you've created would take over and make the front drop out (endo)

Angle, body position shift, throttle

The shock begins to rebound once you have left the ground, making it ineffective on any rebound "lifting" the bike up
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abn166
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6/12/2020 7:13am
aees wrote:
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on...
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on flat ground.

It is a combination of loading the suspension with body position and throttle, as well as taking weight of the seat just before wheels leave the jump face and lifting the bike a bit since you move fwd in the process.

If seat bounce does not work, neither does scrubbing or absorbing suspension travel with legs since it is the direct opposite of seat bounce.

Two persons going up a jump face all things being equal, one will seat bounce I promise you that bike if going higher then the other.

Extra height is typically what you want when seat bouncing, so you don't run the front wheel to short coming into landing or next jump.
I don't think anyone said seat bouncing doesn't work. It just doesn't work by using the shock as some sort of pogo stick as some seem to think.


"It is a combination of loading the suspension with body position and throttle, as well as taking weight of the seat just before wheels leave the jump face and lifting the bike a bit since you move fwd in the process."

Look at the photo of Eli, he is not taking his weight off of the seat just before the wheels leave the ground. No one seat bounces that way.


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aees
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6/12/2020 7:24am
aees wrote:
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on...
It is not the same thing. You have several Gs in force that you experience when you go into a jump face, not so much on flat ground.

It is a combination of loading the suspension with body position and throttle, as well as taking weight of the seat just before wheels leave the jump face and lifting the bike a bit since you move fwd in the process.

If seat bounce does not work, neither does scrubbing or absorbing suspension travel with legs since it is the direct opposite of seat bounce.

Two persons going up a jump face all things being equal, one will seat bounce I promise you that bike if going higher then the other.

Extra height is typically what you want when seat bouncing, so you don't run the front wheel to short coming into landing or next jump.
abn166 wrote:
I don't think anyone said seat bouncing doesn't work. It just doesn't work by using the shock as some sort of pogo stick as some seem...
I don't think anyone said seat bouncing doesn't work. It just doesn't work by using the shock as some sort of pogo stick as some seem to think.


"It is a combination of loading the suspension with body position and throttle, as well as taking weight of the seat just before wheels leave the jump face and lifting the bike a bit since you move fwd in the process."

Look at the photo of Eli, he is not taking his weight off of the seat just before the wheels leave the ground. No one seat bounces that way.


He does, a micro second later just before or at the same time the shock start to rebound. If he don't, he is going to the moon.
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