Seat bounce

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6/11/2020 1:09 PM

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.

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6/11/2020 1:16 PM

Where's TFS when you need him???

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www.bettercallsaul.com
Die Antwoord

6/11/2020 2:05 PM

Miss you #1111

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6/11/2020 2:50 PM

Well if it doesnt bounce you higher then lets say "pounce" you higher.

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All I needs a cool buzz some tasty berms and I'm fine

6/11/2020 2:55 PM

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? Photo

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6/11/2020 2:59 PM

Uh, yeah. You'd know it bounces you higher if you ever did it. Also - traction because you are sitting down and under hard acceleration.

At my age I hate to do it because it is sketchy if you don't do it right. But it is fun to launch on a short runup to a jump.

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6/11/2020 3:09 PM

Why and how did Eli get his foot under the foot peg in that photo? It must be incredible timing to do that, a little too soon and I would think it would jam your foot into the dirt

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6/11/2020 3:13 PM

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 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? Photo

I’m sorry but what exactly do you think happens when you compress a shock spring, it just stays down?

I’ll let the other Vitards with engineering certifications confirm with me, but to my knowledge it goes back up.

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If it can't be fixed with a hammer, it's an electrical problem.

6/11/2020 3:24 PM

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.

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6/11/2020 3:27 PM

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 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? Photo

SeaClassExpert wrote:

I’m sorry but what exactly do you think happens when you compress a shock spring, it just stays down?

I’ll let the other Vitards with engineering certifications confirm with me, but to my knowledge it goes back up.

Tie your bike down in the back of your truck and compress the shock all the way down, then cut the strap. Does it leap? No, it has rebound damping.

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6/11/2020 3:27 PM

Long after I saw that thread I realized why the seat bounce works. I don't think anybody mentioned it, but it is this: "Timing."

TFS's contention was that the spring can only return the same amount of force back to the bike; enough to return the seat to its original position. No more, no less.
Seat bouncers believe that by sitting, you put more force into the shock spring, which then returns more force.

Actually, the answer lies between the inertia of the subframe assembly and the rider's inertia, relative to the footpegs as a moment in time. If the rider sits, and then allows the spring to push his body along with the subframe, it changes the interplay between the bike and rider. The spring can only push the subframe back to its original position, true, but it cannot stop the rider's momentum once it gets there. The rider will continue to move upward and bring the bike with him (assuming he holds on). While standing tends to isolate the bike from the rider and thus dampen the rebound force, sitting pairs them, thus maximizing the rebound force.

One argument the non-bouncers forwarded was that "if seat bouncing works, why don't the bikes bounce off the ground when they land?" Look no further than the tabletop-to-tabletop hop that was popular several seasons ago for the answer: they do, when the rider times the landing accordingly.

Seat bouncing is not about more force in the spring; it is about timing the interplay between the rider's own momentum and the bike's.

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Braaapin' aint easy.

6/11/2020 3:28 PM

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 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? Photo

It’s been talked about here a few times. I’ve seen it in person at Washougal. He does it to scrub sometimes to lift the bike up. Also when seat bouncing I’ve seen it, maybe to save him from going over the bars or to lift the rear end up and leveling the bike?

My friend asked him in the bits and he was pretty chill about it. I think it comes natural without thinking about it for him.

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6/11/2020 3:28 PM

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.

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James

6/11/2020 3:29 PM

The Nick Wey riding coach thread made me think of this again. Just because some fast riders think they can temporarily turn their shock into a pogo stick doesn't make it so. The fast riders who understand it turn into riding coaches and test riders.

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6/11/2020 3:30 PM
Edited Date/Time: 6/11/2020 3:38 PM

Gravity Cavity wrote:

Why and how did Eli get his foot under the foot peg in that photo? It must be incredible timing to do that, a little too soon and I would think it would jam your foot into the dirt

Once I saw a video, don't remember who it was maybe from Nicoletti or Catanzaro. He said he hooked his foot under the footpeg while seatbouncing and in the air it helps the bike going little further, something do do with your body being ejected and taking this updward reaction from you and transferring it to the bike.

EDIT:

It was Jimmy Albertson, but he hooks his foot under the shiftlever not the peg. Maybe the same principle applies. Who knows

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6/11/2020 3:40 PM

I always ride with my feet under the pegs

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6/11/2020 3:43 PM

Maybe we should ask this guy about bouncing.

Photo

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6/11/2020 3:45 PM

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 TFS.

WINNER

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6/11/2020 3:52 PM

SeaClassExpert wrote:

I’m sorry but what exactly do you think happens when you compress a shock spring, it just stays down?

I’ll let the other Vitards with engineering certifications confirm with me, but to my knowledge it goes back up.

Shocks do rebound of course. But look at the photo. Eli's shock will not rebound until the tire has left the ground. So it will be impossible for the shock to act like a pogo and push the bike and/or farther. As others have said above, it's about changing the bike's trajectory.

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6/11/2020 4:05 PM

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

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6/11/2020 4:25 PM

So...no-one-else ever hooks their foot under the peg/brake-pedal during a quick-hi-energy launch?

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I ripped a start from Egypt and I was happy about that.

6/11/2020 4:26 PM

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 TFS.

EngIceDave wrote:

WINNER

Agreed

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6/11/2020 5:06 PM

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 TFS.

EngIceDave wrote:

WINNER

All that would do is give you boner air. The angle of the jump face doesn't change.

If a shock with rebound has no effect, tell me why it doesn't stay in the fully collapsed position? Of course it extends, just not 'immediately" just like a door closer.

https://motocrossactionmag.com/amp/seen-new-mxa-jam-packed-full-motocross/

Photo

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2015 Beta 500 RS, history: 99 KTM 300, 87 CR250, 84 KLR 600, 82 GPZ 550, 81 KX 250, 80 KX 250, 79 Montesa 414 VE, 78 250 VB, 77 360 VB, 76 360 VA, 75 YZ 125, 74 TM 125, 72 TS 125, 60's West Bend Go Boy Kart

6/11/2020 5:11 PM
Edited Date/Time: 6/11/2020 5:13 PM

This gonna be good. Where's Cox?

Here's some chum. How does a low-rider get off the ground?

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6/11/2020 5:21 PM

I don't know how it works but it works. How does Santa deliver all those presents, the Easter Bunny hide those eggs, the tooth fairy get it done, how does a plane fly...magic of course. Don't question it...just believe.

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If it ain't yer's don't take it, If it ain't the truth dont say it, If it ain't right don't do it...Marcus Aurelius

6/11/2020 5:22 PM

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 TFS.

EngIceDave wrote:

WINNER

Johnny Depp wrote:

All that would do is give you boner air. The angle of the jump face doesn't change.

If a shock with rebound has no effect, tell me why it doesn't stay in the fully collapsed position? Of course it extends, just not 'immediately" just like a door closer.

https://motocrossactionmag.com/amp/seen-new-mxa-jam-packed-full-motocross/

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The face the of the jump does effectively change if the sprung parts of the bike (everything above the wheels) is at a different angle.

Let's talk the pre-scrub days... How did Jeremy McGrath master the art of staying lower on jumps? By compressing the forks more (pushing into them more off the face of jumps). Lower angle, lower trajectory.

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James

6/11/2020 5:50 PM

Showtime must've been playing with power to pick up the bike and make that double without seat bouncing it at 38 seconds ..

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All I needs a cool buzz some tasty berms and I'm fine

6/11/2020 7:31 PM

"The face the of the jump does effectively change if the sprung parts of the bike (everything above the wheels) is at a different angle."

Anyone ever try seat bouncing one of these hardtails? w00t

Photo

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2015 Beta 500 RS, history: 99 KTM 300, 87 CR250, 84 KLR 600, 82 GPZ 550, 81 KX 250, 80 KX 250, 79 Montesa 414 VE, 78 250 VB, 77 360 VB, 76 360 VA, 75 YZ 125, 74 TM 125, 72 TS 125, 60's West Bend Go Boy Kart

6/11/2020 7:41 PM

Johnny Depp wrote:

"The face the of the jump does effectively change if the sprung parts of the bike (everything above the wheels) is at a different angle."

Anyone ever try seat bouncing one of these hardtails? w00t

Photo

The item in that picture that’s worthy of a good “seat bounce” ain’t the Capt. America chopper!

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I ripped a start from Egypt and I was happy about that.

6/11/2020 7:55 PM
Edited Date/Time: 6/11/2020 7:57 PM

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?

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