[Steve M]

So what actual advantages does this system offer? (Yes, I've read the whole thread, yes I am familiar with suspension stuff)

As you say yourself, this allows for essentially the same characteristics as an FSR bike - singlepivot pedalling with whatever 4-bar characteristic braking you want to use. It doesn't use a significantly different structure to an FSR design (and thus I'm going to be presumptuous and say it won't be inherently cheaper to manufacture), so what does it actually do that stands it above FSR? Seems to me that any concentric pivot/axle things are usually asking for trouble (at least in terms of ease of design and manufacture, I'm not saying at all that they're necessarily unreliable). The only advantage I can see is if you sell someone the rights to use it and let them design it themselves, whereby they can more easily choose separate pivot position and braking characteristics than they could if they had to do it with an FSR or other true 4-bar linkage (where the CC is not an actual pivot). Is there anything else or is this system really just "competitive" with FSR and nothing more?

 

[jtdcg]

Dirtrag has been reviewing the new EX9 trek with their ABP. If you focus on the supsension they seem to be enjoying so far...
http://www.dirtragmag.com/blogarific/category/product-testing/

I look foward to seeing a split pivot in the future.

 

[syadasti]

In other news the 2008 Trek Remedy series is now posted on their website. See them here

Yes it comes in Root Beer

 

[psychobiker]

great now im getting the 08 DW bikes in and everybody will want the split pivot...lol

 

[caputo1989]

Looks like the new trek EX design.

 

[caputo1989]

Ops beaten to the punch.
It loks like it would work great with a 12mm axle

 

[someguy]

The wheel path is that of a single pivot, but the effect of placing the pivot at the axle is to isolate the braking forces. Thus, there is no brake jack, or chatter under heavy breaking into corners etc. It works really well. As crazy as it may sound... go to a Trek dealer and ride it. You will be amazed. I was.

 

[dump]

hmm... trek, no thanks.

 

[ufdff15]

The wheel path is that of a single pivot, but the effect of placing the pivot at the axle is to isolate the braking forces. Thus, there is no brake jack, or chatter under heavy breaking into corners etc. It works really well. As crazy as it may sound... go to a Trek dealer and ride it. You will be amazed. I was.

I'm pretty sure that the Trek system is not a DW split pivot but their own design that is extremely close in design. Please feel free to correct me if I'm wrong(I'm looking at you Dave ;-) )

 

[Spokompton]

I'm pretty sure that the Trek system is not a DW split pivot but their own design that is extremely close in design. Please feel free to correct me if I'm wrong(I'm looking at you Dave ;-) )

Actually, you are correct to a degree.

Even though the dropout pivot is the same, the Trek system uses a moving lower shock mount that is attached to the main swing arm.

Both designs are basically a cool way to integrate a floating brake to a single pivot.

 

[allsk8sno]

Actually, you are correct to a degree.

Even though the dropout pivot is the same, the Trek system uses a moving lower shock mount that is attached to the main swing arm.

Both designs are basically a cool way to integrate a floating brake to a single pivot.

i love the trek frame....horrible falling rate...what??

 

[springfish]

Didn't MRP patent something like this?

 

[atrokz]

So what actual advantages does this system offer? (Yes, I've read the whole thread, yes I am familiar with suspension stuff)

The main advantage I see is this will work with a gearbox......

Someone needs to do it!

 

[dropmachine]

Its already in the works.

 

[Wilhelm]

Today the German Hamburg based BERGAMONT bike company unveilled two of their all-new for 2009 models ("Straitline 7.9" for DH use, "BigAir 9.9" for FR use) at the bike festival in Willingen (Germany): http://www.mtb-news.de/forum/showthread.php?t=341608.

If you look carefully at the rear suspension you can find Dave´s "Split-Pivot" design in combination with a "Maxle" rear axle as well as a rear postmount. So far as I can see are these two rigs the first series bikes (besides the TREK "ABP" stuff http://thisjustin.bicycling.com/2007/06/08_trek_fuel_ex.html) with this licensed-by-Dave design. Considering the 2007 BERGAMONT "BigAir G9" G-CON gearbox bike project (http://www.mtb-news.de/forum/showthread.php?t=285006&highlight=BigAir, http://bergamont.de/cms/de/02__bikes/freeride_dirt_street_mtb/detail/big-air-g9) i am very hopeful to see the first "Split-Pivot" gearbox bike soon, too.

 

[wuchi]

I don't want to sound negative but what advantage would a split pivot do for a gearbox frame? sure its separates the acceleration forces from braking forces.
but you would still need some device for the chaintension.
it might work with some eccentric-dropout solution but its far more complicated than just mount a floating brakemount round the wheelaxle

 

[Wilhelm]

I don't want to sound negative but what advantage would a split pivot do for a gearbox frame? sure its separates the acceleration forces from braking forces.
but you would still need some device for the chaintension.
it might work with some eccentric-dropout solution but its far more complicated than just mount a floating brakemount round the wheelaxle

IMHO, given that the problem of chain tension will be solved by kind of the mentioned eccentric dropout, e.g. something like the "Ekzentriker" bottom bracket mount by TR!CKSTUFF (http://www.trickstuff.de/index.php?p=d110de1)*, the "Split-Pivot" design offers the advantages of being the less prone-to-damage as well as the more light weight solution over a "full floater". The "Maxle" seems to be a suitable device in this context.

*

 

[no skid marks]

I don't want to sound negative but what advantage would a split pivot do for a gearbox frame?

Isolate braking forces from suspension forces apparently, I'm not sure if this bike will have a bit of brake induced squat or jack though. Seat stay trying to rotate down would induce squat, but the shocks link looks like it'd extend producing jack,not sure what would win or if I'm totally missing something.
Great looking lil DH bike ^^^ , can't wait to hear some feedback on it.

 

[Steve M]

The main advantage I see is this will work with a gearbox......

Someone needs to do it!

Anything else can work with a gearbox too... so?

IMHO, given that the problem of chain tension will be solved by kind of the mentioned eccentric dropout, e.g. something like the "Ekzentriker" bottom bracket mount by TR!CKSTUFF (http://www.trickstuff.de/index.php?p=d110de1)*, the "Split-Pivot" design offers the advantages of being the less prone-to-damage as well as the more light weight solution over a "full floater". The "Maxle" seems to be a suitable device in this context.

*

The problem with using any concentric pivots is that, especially if they're low pivot bikes, they pedal like crap. So you're still going to need a chain tensioner.

Seriously - until dw comes up with some magic reason why this system is awesome, I will restate:

This has no potential for higher performance than FSR does, nor will it be inherently lighter, stiffer, stronger or cheaper to manufacture than FSR. It is simply a marketing man's way to cut in on the FSR slice of the pie without infringing upon their patents or having to use particularly expensive/accurate manufacturing methods.

In a performance sense, it's actually nothing new whatsoever. Fact.

 

[dirtdigger]

Anything else can work with a gearbox too... so?



The problem with using any concentric pivots is that, especially if they're low pivot bikes, they pedal like crap. So you're still going to need a chain tensioner.

Seriously - until dw comes up with some magic reason why this system is awesome, I will restate:

This has no potential for higher performance than FSR does, nor will it be inherently lighter, stiffer, stronger or cheaper to manufacture than FSR. It is simply a marketing man's way to cut in on the FSR slice of the pie without infringing upon their patents or having to use particularly expensive/accurate manufacturing methods.

In a performance sense, it's actually nothing new whatsoever. Fact.

right on brother, i had a similar rant in the thread about the new trek DH frame

 

[norbar]

If only bergamont bikes looked a bit better and had a slightly more agressive geo... Anyway it's nice there's something new going there as you can get some nice prices from them.

 

[DirtyMike]

Something I would have liked to see in a design, maybe someone here can do this, But I would like to see a Main pivot that is around the BB, Like the Cove SHocker, with the ABP axle pivot. I would think that would help out and work well. Correct me if I am wrong, but wouldnt that eliminate chain growth isues???

 

[atrokz]

Anything else can work with a gearbox too... so?

Without the aid of a tensioner? No.

 

[no skid marks]

Without the aid of a tensioner? No.

Most bikes use the gearbox as a tensioner, so yes,accept for anything that has a hugely variable axle path(Older Intense or Santa Cruz, but what's the point in that?).Not sure how variable current SC or Intense are, I think the binned the idea mainly.

 

[atrokz]

Most bikes use the gearbox as a tensioner[/COLOR]

what bikes?

 

[Steve M]

Without the aid of a tensioner? No.

a) It's been done. Centurion had a parallelogram link gearbox bike with no tensioner a while ago (see below), and you could just as easily make an FSR bike with a fixed CC that needed no tensioner.
b) concentric pivot/drive outputs pedal like crap, especially with low pivots, as I mentioned before, so your point is irrelevant as far as high-performance suspension goes anyway.

 

[no skid marks]

what bikes?

My mistake, I meant idler, or thought you did, as a tensioner is really not an issue at all, I overlooked it. I'd rather better suspension design with a tensioner than **** design without.
Here some good designs.
BCDs
GT IT1(let down by geo).
Lahars
Mylard
and a handful of little brand or home made creations.
Has anyone had tensioner issues with any high pivot or VPP style gearbox bikes?

 

[atrokz]

My mistake, I meant idler, or thought you did,

Ah, gotcha.

 

[ire]

a) It's been done. Centurion had a parallelogram link gearbox bike with no tensioner a while ago

Isn't that bike using the Lawwill suspension design? Definitely cool looking

 

[DirtyMike]

Isn't that bike using the Lawwill suspension design? Definitely cool looking

If it isnt, its very similar. I like the looks of that one too!!!

 

[Wilhelm]

a) It's been done. Centurion had a parallelogram link gearbox bike with no tensioner a while ago (see below), and you could just as easily make an FSR bike with a fixed CC that needed no tensioner.
b) concentric pivot/drive outputs pedal like crap, especially with low pivots, as I mentioned before, so your point is irrelevant as far as high-performance suspension goes anyway.

There are some good news concerning the proceeding of this nice LAWWILLish looking gearbox bike project: http://www.troeger-engineering.de, http://www.ridemonkey.com/forums/showpost.php?p=2967838&postcount=632.

 

[ohio]

This has no potential for higher performance than FSR does, nor will it be inherently lighter, stiffer, stronger or cheaper to manufacture than FSR. It is simply a marketing man's way to cut in on the FSR slice of the pie without infringing upon their patents or having to use particularly expensive/accurate manufacturing methods.

In a performance sense, it's actually nothing new whatsoever. Fact.

As much as I'm a (recent) fan of Specialized, patenting the Horst Link and enforcing that patent was a $hitty thing to do to the bicycle industry and us riders. So in the sense that there's some direct competition for the FSR, then YES it is something new and welcomed.

Also, unless it requires bearings on both chain and seat-stay (which I don't think it does) it does have the potential to be a few grams lighter and simpler to manufacture (fewer welds) than an FSR, in an application that was going to use a thru-axle anyway.

 

[bizutch]

can we lock this thread with all it's endless nerdy bickering until the bikes actually come out?

just a thought.........

 

[Lollapalooza]

can we lock this thread with all it's endless nerdy bickering until the bikes actually come out?

just a thought.........

It's a forum. This is where bike nerds assemble to talk about this kind of stuff exactly and play D&D. My 20 sided die says the discussion will continue.

 

[skinny mike]

My 20 sided die says the discussion will continue.

with +2 mana and the shock of infinite compression.

 

[Steve M]

As much as I'm a (recent) fan of Specialized, patenting the Horst Link and enforcing that patent was a $hitty thing to do to the bicycle industry and us riders. So in the sense that there's some direct competition for the FSR, then YES it is something new and welcomed.

Also, unless it requires bearings on both chain and seat-stay (which I don't think it does) it does have the potential to be a few grams lighter and simpler to manufacture (fewer welds) than an FSR, in an application that was going to use a thru-axle anyway.

Yeah but what you gain from the fewer welds, you lose by having a more complex axle/pivot arrangement. I don't see a net gain there.

 

[Steve M]

Isn't that bike using the Lawwill suspension design? Definitely cool looking

No, though it does look similar (especially the upper arm, where it pushes the shock looks a LOT like an old DH9). It's simply a parallelogram, which the Lawwills weren't. Kind of a cool idea but probably adding significant weight to an already heavy frame, cos of the G-boxx thing.

 

[dw]

Today the German Hamburg based BERGAMONT bike company unveilled two of their all-new for 2009 models ("Straitline 7.9" for DH use, "BigAir 9.9" for FR use) at the bike festival in Willingen (Germany): http://www.mtb-news.de/forum/showthread.php?t=341608.
If you look carefully at the rear suspension you can find Dave´s "Split-Pivot" design in combination with a "Maxle" rear axle as well as a rear postmount.

Split Pivot and Bergamont have been involved in discussions about implementing a Split Pivot design on their upcoming models. The prototypes shown at the Willingen show will be used for evaluating some of the mechanical aspects of the Split Pivot concentric dropout design, this bike uses a thru axle. I didn't personally develop the kinematics for this frame but any production bike would use kinematics that I would develop specifically for Bergamont. Its a work in progress.

Dave

 

[dw]

I don't want to sound negative but what advantage would a split pivot do for a gearbox frame? sure its separates the acceleration forces from braking forces.
but you would still need some device for the chaintension.
it might work with some eccentric-dropout solution but its far more complicated than just mount a floating brakemount round the wheelaxle

Split Pivot would have the same exact advantages for a gearbox frame as it would for a standard front derailleur frame. Its not like a chain tensioning or chain slack mechanism needs to be overly complex, every motocross bike in existence uses one. The performance increases in traction, acceleration efficiency, and braking control far outweigh the simple prospect of adding some kind of chain management device. In my typical way, I won't let the words just stand on their own, I intend to prove that to you.

Dave

 

[dw]

Anything else can work with a gearbox too... so?



The problem with using any concentric pivots is that, especially if they're low pivot bikes, they pedal like crap. So you're still going to need a chain tensioner.

Seriously - until dw comes up with some magic reason why this system is awesome, I will restate:

This has no potential for higher performance than FSR does, nor will it be inherently lighter, stiffer, stronger or cheaper to manufacture than FSR. It is simply a marketing man's way to cut in on the FSR slice of the pie without infringing upon their patents or having to use particularly expensive/accurate manufacturing methods.

In a performance sense, it's actually nothing new whatsoever. Fact.

I love that you have become such a confident individual Fatman, think back, just a couple years ago you would come here and ask question after question about suspensions, how they function, etc.. I took a lot of my personal time to humor those questions and to share some of the information with yout that's just not available in books. Today you are here and making definitive statements about theoretical suspension performance. I think that its great to see how your knowledge has grown, and I can't help to feel but just a little bit responsible. Bravo!

That being said however, there are a couple of places that your statement is at least not entirely accurate.

First off, from a structural standpoint, the Split Pivot design does have the potential to be stiffer or stronger for the same weight. It’s simple physics. Less of a moment arm on the pivot = less force in the pivot = less material in the pivot.

Your suggestion that the Split Pivot's dropout pivot is in some way more complex the FSR is amusing at best. In fact, the exact opposite is true. Take apart both systems and count the parts. Typical FSR bikes actually use sex bolt type pivots (for a couple of reasons), and because of that the FSR dropout has MORE parts than the Split Pivot dropout. The concentricity of the Split Pivot dropout also has the advantage of letting the designer use a thru axle type connection straight through the entire chainstay pivot, and potentially stiffening the interconnection even more by creating in effect, one large double shear connection. This is not possible with the FSR layout. Of course, all of this assumes that you have an engineering team that is optimization minded and capable of eliminating weight where they need to. Specialized is awesome at this kind of thing, and they have their FSR bikes designed to the limit from their years and years of experience with the design.

From a performance standpoint, you are correct only if you are talking about identical linkage arrangements. With identical pivot placement of all but the dropout pivot, the Split Pivot and FSR designs are capable of some very similar levels of performance, but only within specific kinematic layouts. There is a wide range of engineering latitude within the Split Pivot patent portfolio that does not exist in the FSR portfolio. A much wider array of link layouts, and because of this, performance characteristics can be achieved with the Split Pivot design.

Feel free to read the Split Pivot patent applications and make your own assessment by following the links below. You will see for certain that there are specific performance characteristics cited in the applications that have never been implemented or are even capable of being implemented with the FSR design.

US20080067772A1

http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=2&f=G&l=50&co1=AND&d=PG01&s1=Weagle&OS=Weagle&RS=Weagle

US20080073868A1

http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&co1=AND&d=PG01&s1=Weagle&OS=Weagle&RS=Weagle

The reality is that suspension characteristics and performance are directly related to the kinematic layout of the links in said system. Why would I spend my time working to optimize someone else’s design when I could spend the same amount of time optimizing my own. I know that there is a good deal of capability within the Split Pivot design to build bikes that are stronger, lighter, and better performing than some of their counterparts. Like I said earlier though, you need an engineering team with the skill and knowhow to make it happen. I think that you will be happily surprised with the ride of the true Split Pivot bikes when you get a chance to ride one. I wish I could tell you an exact date when that will be, but that’s not something that is in my power.

Hope this clears some things up or at least motivates you further to keep learning.

Dave