[dw]

Wouldn't having the rear suspension pivot around the drive cog in a high pivot location, such as on the jack shafted Brooklyn race-link isolate the two forces?

simple answer: nope. CHeck out the archives though, this has been discussed and dissected to all holy hell!

Dave

 

[dw]

also, theres a point where we are just splitting performance-hairs, where some 'impressive' engineering numbers between systems dont necessarily translate into a noticible or justifiable performance difference, where a more simplified and practical design that also lowers cost and maintenance concerns is deemed more disirable.

I am not sure what you are implying, but once you get to actully ride one of the dw-link Sundays on a DH course, you come pack an tell me about noticable differences. Hows that sound?

Fact is that I personally cleared hills on my Hollowpoint that I coulnt even approach on my Superlight (which was a damn good single pivot bike).

dw

 

[shock]

simple answer: nope. CHeck out the archives though, this has been discussed and dissected to all holy hell!

Dave

Discussion is not proof. I'm not talking about the bikes listed, (because I have no personal experience with them) but just because it hasn't been done doesn't mean it can't be done...

BTW, the floating brake has been discussed and dissected to holy hell, but I have yet to see the ONE TRUE ANSWER, and we (Therapy Componets)arguably have more experience on that subject than anyone....

 

[dw]

heh

youre right Brian, discussion is not proof, but analysis backed up with data aquaistion during testing that proves pre existing analysis is about as close as it gets. Squat response in suspension under powered acceleration is far more quantifiable than braking response in suspension under decelleration. I'm not getting into that in any more depth here though. We can talk over beer at Interbike .

See you in a few weeks

Dave

 

[shock]

I am not sure what you are implying, but once you get to actully ride one of the dw-link Sundays on a DH course, you come pack an tell me about noticable differences. Hows that sound?

Fact is that I personally cleared hills on my Hollowpoint that I coulnt even approach on my Superlight (which was a damn good single pivot bike).

dw

I know this wasn't directed at me, but I'd love to try the dw link bike, and I'd also love to try a floating brake on that bike. I know you've stated that it doesn't need it (as have all the fsr fans), but you know me, I will maintain that as long as the brake caliper is bolted to the suspension, the force MUST BE transmitted to the suspension, and that a floating brake will be better. I'd love to arrange a test....................

Note: I am not saying all bike designs are equal in the way they manage this force, but they are all affected.

As far as personal accomplishments on one bike design versus another, it's entirely possible that rider technique may come into play. Often new designs are the cure for a problem that not everyone is afflicted with, but the designer has a particular issue with.

Again, i offer the floating brake as an example...How many riders of high single pivot bikes say that they wouldn't benefit, because they don't have a problem with "brake jack". I personally do have a problem with it, therefore I feel it would be a benefit to everyone....

 

[TWISTED]

Floating disc brakes.
If a bike has a perfectly verticle axle path, how would you choose to manipulate the brake forces? Unless I understand the action and intent of floating disc brakes incorrectly?

 

[ChrisKring]

Heck yeah, it would definitley have all of the same performance advantages as on a derailleur bike.



Problem with that is that you can't "isolate the drive forces from the suspension" with a high single pivot like on a Motocross bike. Its just that a motocross bike doesnt complain about pedal feedback and the like.

MX engines also turn out a smooth power output at 10,000 rpm and don't bounce up and down. While a DH bike/rider is not smooth at all on the power output and does it at 40-120 rpm while the "engines" COG is bouncing all over the place.

 

[MikeD]

MX engines also turn out a smooth power output at 10,000 rpm and don't bounce up and down. While a DH bike/rider is not smooth at all on the power output and does it at 40-120 rpm while the "engines" COG is bouncing all over the place.

Not to mention that the relative mass of the 'pistons' (ie, feet) is a lot greater compared to the overall mass of the bike than a single cylinder is to an MX bike...

 

[dw]

MX engines also turn out a smooth power output at 10,000 rpm and don't bounce up and down. While a DH bike/rider is not smooth at all on the power output and does it at 40-120 rpm while the "engines" COG is bouncing all over the place.

You got it brother!

Plus the MX engine doesnt have feelings to hurt or a mouth to complain with

dw

 

[dw]

I know this wasn't directed at me, but I'd love to try the dw link bike, and I'd also love to try a floating brake on that bike. I know you've stated that it doesn't need it (as have all the fsr fans), but you know me, I will maintain that as long as the brake caliper is bolted to the suspension, the force MUST BE transmitted to the suspension, and that a floating brake will be better. I'd love to arrange a test....................

Note: I am not saying all bike designs are equal in the way they manage this force, but they are all affected.

As far as personal accomplishments on one bike design versus another, it's entirely possible that rider technique may come into play. Often new designs are the cure for a problem that not everyone is afflicted with, but the designer has a particular issue with.

Again, i offer the floating brake as an example...How many riders of high single pivot bikes say that they wouldn't benefit, because they don't have a problem with "brake jack". I personally do have a problem with it, therefore I feel it would be a benefit to everyone....

There is no doubt that a floating brake kit could "alter" the braking performance on the Sunday, but the bike was designed to have a specific function under braking. Absolutely I could attain the same desired acceleration characteristics with a different braking characteristic.

The thing is, this exact layout is where the 2 years of real world testing and analysis left us, so we are pretty confident with it. Again, I'm not saying that it cant be altered, and maybe some riders would like or dislike the changes. There are plenty of bikes out there that NEED a seperate floating brake in my opinion, but the Sunday was designed from the beginning to perform a specific function under braking.

I am psyched for you and your priduct, but I am sure that Iron Horse would not even consider warrantying a frame fit with an external floating brake. The bike was never, and will never be intended to use one. It just does such a damn good job on its own!

We can still be friends though

See you at the show Brian, I will arrange a ride for you at ODD in Vegas.

Dave

 

[shock]

heh

youre right Brian, discussion is not proof, but analysis backed up with data aquaistion during testing that proves pre existing analysis is about as close as it gets. Squat response in suspension under powered acceleration is far more quantifiable than braking response in suspension under decelleration. I'm not getting into that in any more depth here though. We can talk over beer at Interbike .

See you in a few weeks

Dave

Ok, and now we're really getting deep, (and I think this thread is getting seriously derailled)

but certainly power delivery during acceleration is as much if not more of a variable on a mountain bike than brake force, i.e, pedalling "circles vs squares", clipped in vs flats, rider cg and his management therof (like standing or seated, and associated leverage effects thereof). Not to mention crank length and gearing effects, front and rear. In addition to selective power input vs various terrain features (like where you choose to pedal hard).

Now braking certainly is affected by where you choose to brake hard, and rider cg and management, but none of the other leverage issues really come into play (for a given suspension design).

As for data acquisition, I remember a discussion with a data acquisition engineer about the accuracy of the damper traces at Indy. I believe the maximum sampling rate at the time was 200hz (200 times per second). Some quick math revealed that we were sampling the shock movement once every 1.8 ft at 245 mph (or something like that but I've had a margurita or two, and I could be off (in more ways than one)). So we were missing a lot of stuff in between.

My point here is that data acquisition is just a tool, and can be used to prove anything you want, sometimes without even knowing. (kinda like math and statistics)

Ok, and I think I owe you that beer, tell me what you're drinkin and I'm buyin..

Brian

 

[shock]

Floating disc brakes.
If a bike has a perfectly verticle axle path, how would you choose to manipulate the brake forces? Unless I understand the action and intent of floating disc brakes incorrectly?

Well we're kinda cheating there, since a front fork is really the only suspension on a bike that has a staight line axle path (and that is a very interesting subject for another day), but a fork has very different force inputs and leverages acting on it, and can't really be compared to a rear suspension in theis context.

But for example, I believe the lawill type suspension, as used on the Yeti and older Tomac designs, is highly touted for it's near linear axle path. Yet this design is one that can benefit the most from a floater, due to it's tendency to rise up under braking. This has much more to do with how the caliper is mounted to which suspension link, and how those reaction forces relate to the tire contact patch and the other suspension links, and the associated moments and leverages on those links. (boy that was a mouthfull, did it make any sense?)

But the basic answer, is that a floater can remove the braking forces from the suspension, allowing whatever "ideal" compromise that the designer intends, between damping, spring, rate management, axle path, etc, to operate as it was intended, without the input of up to 1000 pounds of braking force...

Or in some instances, managed for another purpose, i.e. Fabien Barel's "squat and thrust" (I just love saying that)

 

[dw]

Hell yeah, sounds good man. and yeah, you gotta keep those sampling rates up. Im pumping 1000Hz on most points. Thats screaming, but the DAQ i'm using is screaming expensive too. You would **** if you saw all the stuff I actually sample. Ive never seen or heard of anything like it.

dw

 

[ChrisKring]

As for data acquisition, I remember a discussion with a data acquisition engineer about the accuracy of the damper traces at Indy. I believe the maximum sampling rate at the time was 200hz (200 times per second). Some quick math revealed that we were sampling the shock movement once every 1.8 ft at 245 mph (or something like that but I've had a margurita or two, and I could be off (in more ways than one)). So we were missing a lot of stuff in between.

My point here is that data acquisition is just a tool, and can be used to prove anything you want, sometimes without even knowing. (kinda like math and statistics)

Ok, and I think I owe you that beer, tell me what you're drinkin and I'm buyin..

Brian

Now you started it.

Reportly, Dave has a data acquisition system that makes the Shock Tech look like a echa sketch. I would like to get my hands on this system. Most good data acquisition are too big and bulky to use in a DH situation.

That said, I think the Shock Tech system would help me with fine tuning my racers suspension. Some of them are good at telling me what is going on which makes tuning a little easier. While others are close to my weight and riding style so I can set it up for me and let them tell me where it isn't working and where it works great. Then there is the rider that can't tell me anything and weighs a fraction of my weight.

 

[shock]

There is no doubt that a floating brake kit could "alter" the braking performance on the Sunday, but the bike was designed to have a specific function under braking. Absolutely I could attain the same desired acceleration characteristics with a different braking characteristic.

The thing is, this exact layout is where the 2 years of real world testing and analysis left us, so we are pretty confident with it. Again, I'm not saying that it cant be altered, and maybe some riders would like or dislike the changes. There are plenty of bikes out there that NEED a seperate floating brake in my opinion, but the Sunday was designed from the beginning to perform a specific function under braking.

I am psyched for you and your priduct, but I am sure that Iron Horse would not even consider warrantying a frame fit with an external floating brake. The bike was never, and will never be intended to use one. It just does such a damn good job on its own!

We can still be friends though

See you at the show Brian, I will arrange a ride for you at ODD in Vegas.

Dave

I'm not sure how the warranty affects this discussion, or even the bike's intended design purpose under braking....unless it's tested WITH one, it's all just conjecture. I would really love to put one on and see the effect. It could be surprising for both of us (or maybe just me!!!). Just like Fabien's geometry.

Always a pleasure Dave, you lnow I just love stirring it up and making people think. Absolutes bug me (unless of course I'm the proponent)

Ok, now BACK TO WORK (sound of my boss cracking the whip in the background)

 

[shock]

dammit I can't even type enough to keep up with this, don't you people have anything better to do at midnite?!?!?! I'm going to bed (to work in my sleep)

Tomorrow

 

[TWISTED]

Brian, what I was trying to say was, there must be some suspension design that would not need an added on floating kit. Don't some suspension linkage designs already contain the traits you try to accomplish with your kit. Or perhaps you have a design in mind that you prefer.

I thought a floating brake was meant to allow the suspension to cycle through the stroke without the brakes having an ill effect, whether to imply an extending or compressing force.

I saw a guy on a demo 9 lock the rear brake then bounce on the seat to run the bike through it's travel. The drop-out, chain, and rear derailleur did not move. This made me think this bike would not need a floater, but of course I'm wrong, yes?

I'm no engineer or college grad, but an industry guy on the production end who rides every day, and has a strange imagination.

 

[zedro]

I saw a guy on a demo 9 lock the rear brake then bounce on the seat to run the bike through it's travel. The drop-out, chain, and rear derailleur did not move. This made me think this bike would not need a floater, but of course I'm wrong, yes?

oooo dont use the word "need", to me thats a no-no. This is what i mean about splitting-hairs, what is subtle and almost indistinguishable (holy crap that cant be spelled right) to one rider can be an obvious sore spot to another.

For example, Brians a crusader for perfect braking tendacies so he'll probably say yes, whereas someone else will say they just blew all their money on a Demo9 and cant afford to care even if it is needed...

 

[vitox]

Problem with that is that you can't "isolate the drive forces from the suspension" with a high single pivot like on a Motocross bike. Its just that a motocross bike doesnt complain about pedal feedback and the like.

Are you sure about that????????? Never say never.......[/QUOTE]


chain therapy ®

 

[TWISTED]

oooo dont use the word "need", to me thats a no-no.
For example, Brians a crusader for perfect braking tendacies so he'll probably say yes, whereas someone else will say they just blew all their money on a Demo9 and cant afford to care even if it is needed...

Shhhhhh, I know, I know. I was catering the question toward him.

 

[DßR]

FWIW, the Demo9 is the only bike I've ever seen that looks like it already has a floating brake in place -- you can bounce up and down, and the position of the brake caliper relative to the mainframe, rotor, whatnot, does NOT change at all. Pretty cool looking really...

 

[zedro]

FWIW, the Demo9 is the only bike I've ever seen that looks like it already has a floating brake in place -- you can bounce up and down, and the position of the brake caliper relative to the mainframe, rotor, whatnot, does NOT change at all. Pretty cool looking really...

proper variations in caliper rotation are very slight and not really visible tho. You just cant look at it, nor assume the forces input into the frame.

 

[ChrisKring]

It's funny how many people "need" a floating brake or whatever the latest trendy part is but have no idea what their tire pressures are. Hint: tire pressure is one of the most important set up items for DH.

 

[DßR]

but have no idea what their tire pressures are. Hint: tire pressure is one of the most important set up items for DH.

hmm, so just squishing them and saying "that feels about right" is no good eh? Damn...

 

[math2014]

hmm, so just squishing them and saying "that feels about right" is no good eh? Damn...

Thats exactly how i check it!

 

[dante]

I thought you checked tire pressure by riding something, sliding out, take air out of the tire for about 5-7 sec, pump on it by hand to make sure it's not *too* soft, and go.

Oh yeah, and not to throw MORE gasoline on the fire, but the Sunday Prototype that I'm riding feels better under braking than a bike that has completely neutral braking characteristics... "and that's all I'm gonna say about that."

(oh crap, I've said to much, dw's gonna kill me... )

 

[math2014]

Does IH has european distributors???

 

[binary visions]

(oh crap, I've said to much, dw's gonna kill me... )

It has been mentioned/discussed on here that a certain amount of squat is a desirable braking characteristic, and IIRC dw was one of the ones discussing it...

 

[MikeD]

Oh yeah, and not to throw MORE gasoline on the fire, but the Sunday Prototype that I'm riding feels better under braking than a bike that has completely neutral braking characteristics...

Wow, it's got the new Braking+ option! Like normal braking...just a little bit more!

 

[UiUiUiUi]

Does IH has european distributors???

as far as i know they don't.
but they are looking for partners.
at least thats the info i got on eurobike.

 

[shock]

Hell yeah, sounds good man. and yeah, you gotta keep those sampling rates up. Im pumping 1000Hz on most points. Thats screaming, but the DAQ i'm using is screaming expensive too. You would **** if you saw all the stuff I actually sample. Ive never seen or heard of anything like it.

dw

Ok, but even at 1000 hz, at 30 mph, that's more than 1/2 inch between samples, so did you sample at the point of impact, or just after? That makes a huge difference in the force or displacement reading.

And what's worse is that the sample will occur at a different point with each succesive run, not to mention that the track changes. Even on a stable course like a paved race car course, trying to make sure the data you're looking at is for the same point lap after lap, is impossible.

I won't even get into the filtering that's necessarry (which further corrupts the data) or the aliasing effects.

Don't get me wrong, I'm not saying that data acquisition is useless or wrong, but there are inherrant inaccuracies that have to be taken into account, and should keep the engineer from being too confident that what he is recording is the "truth". It's just another tool.

 

[MikeD]

Hey, who let the real engineers in? This forum is for amateur speculation ONLY. You guys are BOOOOOORRRRRR-IIIIINNNNNGGGGGG....

 

[syadasti]

It has been mentioned/discussed on here that a certain amount of squat is a desirable braking characteristic, and IIRC dw was one of the ones discussing it...

I've heard that from various engineers and riders - a little stability is desired over maximum possible traction for the majority of riders...

 

[shock]

Brian, what I was trying to say was, there must be some suspension design that would not need an added on floating kit. Don't some suspension linkage designs already contain the traits you try to accomplish with your kit. Or perhaps you have a design in mind that you prefer.

I thought a floating brake was meant to allow the suspension to cycle through the stroke without the brakes having an ill effect, whether to imply an extending or compressing force.

I saw a guy on a demo 9 lock the rear brake then bounce on the seat to run the bike through it's travel. The drop-out, chain, and rear derailleur did not move. This made me think this bike would not need a floater, but of course I'm wrong, yes?

I'm no engineer or college grad, but an industry guy on the production end who rides every day, and has a strange imagination.

One critical effect that the bouncing on the seat doesn't reveal (or the spin the cranks with the shock off and slam on the brakes), is the effect of the braking force on the contact patch of the tire to the ground. This force has a great deal of leverage on the suspension, and as the wheel approaches lockup, the whell and suspension become one solid lump being dragged accross the ground.

If the caliper is bolted to the same piece of metal that the hub is bolted to, they become one unit, period. I don't care how many links, struts or dealybobs connect that piece of metal to the frame. The reaction force of the brake caliper MUST be transmitted to that piece of metal, and since that piece of metal holds the wheel, which in turn is responsible for actuating the suspension, that braking force must affect suspension.

Note: I am NOT saying all suspension designs are equal in this regard, obviously a simple change inpivot height has a big effect on this leverage.

 

[shock]

oooo dont use the word "need", to me thats a no-no. This is what i mean about splitting-hairs, what is subtle and almost indistinguishable (holy crap that cant be spelled right) to one rider can be an obvious sore spot to another.

For example, Brians a crusader for perfect braking tendacies so he'll probably say yes, whereas someone else will say they just blew all their money on a Demo9 and cant afford to care even if it is needed...

Yeah, the word "need" is a bit inappropriate, we'd all be riding huffys and dragging our feet on the ground to stop if we had to.

And to clarify, I'm not as much a crusader for perfect braking as for perfect suspension while braking. We spend all this time and money to get the right spring/shock etc for our weight/riding style/terrain, and then throw that out the window by introducing another force. But a byproduct of perfect suspension while braking is of course better braking! cause the suspension keeps the wheel on the ground!

 

[shock]

Are you sure about that????????? Never say never.......

chain therapy ®[/QUOTE]

Bwahahahahaahahahahaha, wringing hands with evil intent...

Actually some wacky guy named horst did that for mx bikes a long time ago, and most people decided the effect of power on the chain and suspension were a good thing!

 

[shock]

Hey, who let the real engineers in? This forum is for amateur speculation ONLY. You guys are BOOOOOORRRRRR-IIIIINNNNNGGGGGG....

Yeah I know, sorry about that, and I swear I promise I'm not going to contribute to the hijacking of this thread any more, no matter what any body else says or argues or proves me wrong (especially the last part)!

 

[zedro]

Yeah, the word "need" is a bit inappropriate, we'd all be riding huffys and dragging our feet on the ground to stop if we had to.

And to clarify, I'm not as much a crusader for perfect braking as for perfect suspension while braking....

dont take it as a slight, just pokin ya'

and MikeD can return to the 5th ring of hell....this has been one of the more interesting threads in a long while :mumble:

 

[shock]

dont take it as a slight, just pokin ya'

and MikeD can return to the 5th ring of hell....this has been one of the more interesting threads in a long while :mumble:

Yeah, I know, I was just gittin all up an engineerin an stuff, visors down, blinders on, full speed ahead....you know what I'm talkin bout

 

[MikeD]

dont take it as a slight, just pokin ya'

and MikeD can return to the 5th ring of hell....this has been one of the more interesting threads in a long while :mumble:

Ahem, that's the 7th.

You can go back to wagging your tail and slugging martinis now, too, mutt-man.

MD