[SVSocrates]

Ventana adopting Dave Weagle's "Split Pivot" design in its future bikies?

 

[The Squeaky Wheel]

My guess is that we won't being seeing these on Ventanas any time - although it is a cool concept

 

[Flyer]

If Sherwood could utilize this to better absorb square-edged hits AND still keep the Ventana stiffness, he may look into it. If not, he probably will not care and nor will most Ventana fans. It is nice to see some new designs coming out though.

 

[Ciclistagonzo]

If Sherwood could utilize this to better absorb square-edged hits

I doubt the split pivot design will do much to change the characteristics of the suspension feel or behavior. The design is still a single pivot, with a fixed length swingarm, it's the arc and the placement of the main pivot that determine how the suspension reacts to bumps. What the split pivot does do is free up the suspension from braking forces.
However, Sherwood's pivot placements cause the rear to squat a bit, and I'm not sure if I want to elimanate that. On my longer travel bike (Bruja), I can tell it happens more than the Salt, and I think I'd prefer the squatting vs. a stinkbug effect.

I do like the Split pivot, it's a creative and SIMPLE idea. It passes the KISS principle beatuifully. Kudo's to DW on it's design. Would I like to see a Salty/Ciclon with it? Yeah, I thinks that might be a very good application of it. Longer travel than that? I'd stick with the current Ventana design.

Just my Over inflated $0.25 worth...

 

[The Squeaky Wheel]

However, Sherwood's pivot placements cause the rear to squat a bit, and I'm not sure if I want to elimanate that.

Agreed. The inherent brake squat on my TMoto provides very controlled descents through steps & ledges. OTOH, a more active rear brake would be a welcomed upgrade for this skidiot.

 

[Ciclistagonzo]

. OTOH, a more active rear brake would be a welcomed upgrade for this skidiot.

I don't skid on my Bruja much at all, but then again, What I ride and what YOU ride are DRASTICALLY different so I'm not surprised if you are pushing the limits of traction and suspension design more than I do! :thumbsup:

 

[SVSocrates]

Wouldn't the SP theoretically allow a different pivot placement? Would someone explain the difference between stinkbugging (brake jack?) and squat. Is stinkbugging merely the opposite? Kind of a bizarre name, yes?

 

[Ciclistagonzo]

I'm not quite sure what you are asking in the first question. Do you mean will the Split pivot lend to moving the main pivot (behind the BB)? I don't believe so since the main pivot is the dictating factor in suspension dynamics on any Single Pivot design. Even DW says so in his posts about the Split pivot. Sherwood has already found the best location for the main pivot for his style of frames.

On the brake jack Q. Stinkbugs are an insect that lifts it's bottom up high and lowers it's head. The FSR bikes and some SP bikes do this when you apply the brakes, the rear suspensions wants to EXTEND. Ventana's do the opposite they want to squat a tiny bit. This helps counter the natural weight shift forward and helps balance the suspension. The down side is, the rear suspension does not track the ground as smoothly as an FSR or probably a Split Pivot bike will. But this is ONLY when you are applying the brakes. The rest of the time the frame stiffness make it a superior design as the bike tracks straight and true.

Did that help any?

-Aaron
(Not a bike designer, but I play one on the Internet)

 

[mtnbiker4life]

I'm not quite sure what you are asking in the first question. Do you mean will the Split pivot lend to moving the main pivot (behind the BB)? I don't believe so since the main pivot is the dictating factor in suspension dynamics on any Single Pivot design. Even DW says so in his posts about the Split pivot. Sherwood has already found the best location for the main pivot for his style of frames.

On the brake jack Q. Stinkbugs are an insect that lifts it's bottom up high and lowers it's head. The FSR bikes and some SP bikes do this when you apply the brakes, the rear suspensions wants to EXTEND. Ventana's do the opposite they want to squat a tiny bit. This helps counter the natural weight shift forward and helps balance the suspension. The down side is, the rear suspension does not track the ground as smoothly as an FSR or probably a Split Pivot bike will. But this is ONLY when you are applying the brakes. The rest of the time the frame stiffness make it a superior design as the bike tracks straight and true.

Did that help any?

-Aaron
(Not a bike designer, but I play one on the Internet)

Aaron - You're doing a great job at bike designer I'd rather do a little squat and let the suspension smooth it out then the stinkbug. Stinkbugging lends itself to a whole host of other bike handling problems.....but that's just me doing some visual analysis since I have never owned or operated a real stinkbugger. Oh, I guess my GF Sugar was a little stinkbugger but at 2.5 inches of travel and V-brakes I really did experience it.

 

[SVSocrates]

I'm not quite sure what you are asking in the first question. Do you mean will the Split pivot lend to moving the main pivot (behind the BB)? I don't believe so since the main pivot is the dictating factor in suspension dynamics on any Single Pivot design. Even DW says so in his posts about the Split pivot. Sherwood has already found the best location for the main pivot for his style of frames.

I'm basically asking if using a split pivot will allow moving the main pivot to improve the ride. Where exactly the pivot would be placed is a bit beyond my understanding of suspension dynamics, but I have noticed under heavy braking that my Ventana "skips" a bit. I realize that the main pivot is the dictating factor in suspension dynamics, but I also realize that pivot placement represents a compromise. You say Sherwood has found the best place for the pivot "for his style of frame." What I am asking is if using the split pivot would allow less of a compromise and allow Sherwood to design a frame, or "style of frame" that could be an even better all around performer?

The down side is, the rear suspension does not track the ground as smoothly as an FSR or probably a Split Pivot bike will. But this is ONLY when you are applying the brakes. The rest of the time the frame stiffness make it a superior design as the bike tracks straight and true.

Vertically or laterally? It seems to me that the more the wheel remains in constant contact with the terrain as a result of suspension action, i.e. vertical activity, the more "straight and true" a bike will ride. Perhaps I am misunderstanding?

 

[P Fradale]

As mentioned in the referenced thread, wouldn't a floating brake assembly do much the same thing for any of the Ventana frames? I believe DW said it would, but it would weigh a bit more. It would, however, obviate the need for another license to use the design, no?

 

[Ciclistagonzo]

I have noticed under heavy braking that my Ventana "skips" a bit....What I am asking is if using the split pivot would allow less of a compromise...

Vertically or laterally? It seems to me that the more the wheel remains in constant contact with the terrain as a result of suspension action, i.e. vertical activity, the more "straight and true" a bike will ride. Perhaps I am misunderstanding?

Wow, lots of questions there!
Here's my best attempt at answers for you. :thumbsup:

The skipping you are feeling is what I was describing in my second post. Where the Single pivot suspension is being compressed by the brakes because the brake is mounted to the Swingarm. This feeling and reaction (to the physics involved) does not get affected by the location of the swingarm's main pivot unless you drastically change that location. Such as moving it halfway up the seattube or way below the BB neither is very practical and both will drastically either worsen the compression or cause the extension of the Swingarm upon braking. So long answer short: The BB pivot is already at the best location for the Single Pivot design.

What would the Split Pivot Change? (Note: I said change not improve) The very thing you are feeling. In Theory, the split pivot creates a floating brake assembly out of the chainstays. But then, you would lose what a few us believe is the beneficial brake squat of the Ventana design.
The bike would follow the terrain a little better, (ie less skipping as you put it) but then the rear end would will be free to extend up and exagerrate the foward weight shift of hard braking. IMOHO I don't like that, I think the Ventana's characteristics tend to make a more predictable and easier to ride bike. And because Ventana's have only a little bit of compression it's easily overcome by bump forces and the rear end stays active.

You are correct, the more "vertical activity" the suspension has the better it is should track.
I was referencing Lateral stiffness. The Ventana frames are, as you know, are known for their lateral strength, the big benefit here is, the rear wheel will not twist and deflect within the frame, If the rear wheel is twisting and not tracking straight the bike will handle poorly in corners and not maintain the line you're trying to take in rough stuff.
Both of which Ventana's excel at.

Ok, my fingers hurt now....

 

[TIGMAN]

Hmmmm............... lets see if I got this straight so the bottom line is its better to ride a squatter rather than a stinkbug ! Actually its seems I noticed the squat effect more on my first Ventana ( Salt w 5 rockers ) maybe I'm just too used to it by now and don't think about it anymore ! TIG.

 

[SVSocrates]

Thanks my man. Great, clear answers. I'd be interested to see the SP implemented just to get a "feel" for it. It might suit my ridng style better, or, it might not.

 

[Ciclistagonzo]

Aaron - You're doing a great job at bike designer .

Thanks Vince, coming from you, that means a lot.

Oh and about your Fisher. All I have to say is....

"Gary Invented them, Sherwood Perfected them."
[email protected] Sea Otter 2007, in the middle of a group ride with Gary Fisher and Sherwood.

 

[Ciclistagonzo]

Thanks my man. Great, clear answers. I'd be interested to see the SP implemented just to get a "feel" for it. It might suit my ridng style better, or, it might not.

You're quite welcome, and frankly, thank you. It's been a few years, since before the previous board format change, that I wrote a disrotation on suspension dynamics. It was fun to dive back into it again.

I agree as well, I would like to try a split pivot Salty/Ciclon, IF, and it's a big if, the lateral strength that Ventana's are famous for, can be maintained. I think the 4/5" frames would be a good application of the Split. I don't believe brake squat is as important in the lower travel applications vs the Bruja/Tmoto/X6 frames.

-Aaron

 

[SVSocrates]

Aaron,

Remember this discussion?

Anyhoo, what I was trying to ask you at the time is stated succinctly in this post:

http://forums.mtbr.com/showthread.php?p=3181362#poststop

Note _dw's response to it.

Thoughts?

Thanks,

Michael

 

[Ciclistagonzo]

Aaron,

Remember this discussion?

Anyhoo, what I was trying to ask you at the time is stated succinctly in this post:

http://forums.mtbr.com/showthread.php?p=3181362#poststop

Note _dw's response to it.

Thoughts?

Thanks,

Michael

Thoughts? Lot's! About the DW link?
OH! (kidding)

Not much different than before. The Main Pivot won't move, it was already at the best location for what Sherwood wanted in his suspension characteristics. Only the Braking physics would change.

-A

 

[FoShizzle]

DW links are ghey

 

[The Squeaky Wheel]

Thoughts? Lot's! About the DW link?
OH! (kidding)

Not much different than before. The Main Pivot won't move, it was already at the best location for what Sherwood wanted in his suspension characteristics. Only the Braking physics would change.

-A

My unsolicited 2 cents....

While I'd like my Terremoto's rear to be a bit more active under rear braking, I've come to love the mild rear end squat it produces. Having some squat in the rear is really helpful on steep terrain and makes the bike feel very stable on steep descents. For comparison's sake, my old FSR bikes may have been "neutral" under braking, but I always felt a bit pitched forward on steep terrain. Of course one could compensate by increasing slow speed compression damping on the fork, bu that comes at the expense of decreasing the fork's sensitivity.