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The Ancient One
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Discussion Starter · #1 · (Edited)
Cactuscorn wanted me to analyze a bunch of bikes. Well what I'm going to do is give the brake squat percentages. These numbers multiplied by the force acting at the rear ground contact point to slow the bike tell how much of that force goes towards compressing the rear suspension. The base figures for the Turner 6-Pack were .86 for the TNT and .48 for the HL. All these are measured at about 25% sag.

Specialized Enduro: ~.75 (approximate because I couldn't get a good profile picture.)

Cannondale Prophet: .80

Ellsworth Distance: about the same as Cannondale

Ellsworth Id: Tall version: .56; Cali.version: .49 (my bike)

Giant Reign: about the same as Cannondale

Santa Cruz Heckler: .76

Santa Cruz Nomad: about the same as Cannondale

Kona Coiler: .83

Iron Horse Mark III: .79

Yeti 575: .87

Yeti ASX: .90

Ellsworth Moment: .30

Now our expert evaluators tell us that there is no perceptible difference between the Turner TNT and HL at .86 and .48. So I guess these figures tell us that there's three times as much imperceptible brake squat on a Yeti ASX as on a Moment.
 

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It's a Turner!
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528 Posts
Actually that's not entirely true. At least one person said they felt slightly more squat on the TNT v HL and they preferred that because it kept the bike more level on steep drops. Anyway, I tend to believe real world tests, however qualitative, over theory. This information makes about as much sense to me as a bag of hammers.



Steve from JH said:
Now our expert evaluators tell us that there is no perceptible difference between the Turner TNT and HL at .86 and .48. So I guess these figures tell us that there's three times as much imperceptible brake squat on a Yeti ASX as on a Moment.
 

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Rolling
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11,120 Posts
Gosh, being a physics kind of guy, I just want to huck my ride off a cliff and see if Newton's Laws still apply.

If Brake squat is a 1% effect on performance, does three times that really matter? I suppose so, if you focus on that part of it.
 

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A few quick questions for you Steve.

Explain the position of IC(HL) vs. TNT(pivot) in your diagram. What do those lines represent? It has been awhile since I studied four-bar linkages.

Also, what are your credentials? You an ME with a background in dynamics? Your analysis seems focused on static loads.

Steve from JH said:
Cactuscorn wanted me to analyze a bundch of bikes. Well what I'm going to do is give the brake squat percentages. These numbers multiplied by the force acting at the rear ground contact point to slow the bike tell how much of that force goes towards compressing the rear suspension. The base figures for the Turner 6-Pack were .86 for the TNT and .48 for the HL. All these are measured at about 25% sag.

Specialized Enduro: ~.75 (approximate because I couldn't get a good profile picture.)

Cannondale Prophet: .80

Ellsworth Distance: about the same as Cannondale

Ellsworth Id: Tall version: .56; Cali.version: .49 (my bike)

Giant Reign: about the same as Cannondale

Santa Cruz Heckler: .76

Santa Cruz Nomad: about the same as Cannondale

Kona Coiler: .83

Iron Horse Mark III: .79

Yeti 575: .87

Yeti ASX: .90

Ellsworth Moment: .30

Now our expert evaluators tell us that there is no perceptible difference between the Turner TNT and HL at .86 and .48. So I guess these figures tell us that there's three times as much imperceptible brake squat on a Yeti ASX as on a Moment.
 

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Never enough time to ride
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1,575 Posts
I have a great idea guys. Instead of waisting our time with meaningless numbers and trying to prove that what ever "wonder linkage" is new and cool today has x amount more brake squat or bobs less than this thing overhere, or what ever the hell else. How bout we get off our butts, ride and let this whole subject fade away into the archive pages somewhere.

Sound like a plan??

Okay I feel better now.

happy trails...

squish
 

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The Ancient One
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1,573 Posts
Discussion Starter · #8 ·
jBailout said:
A few quick questions for you Steve.

Explain the position of IC(HL) vs. TNT(pivot) in your diagram. What do those lines represent? It has been awhile since I studied four-bar linkages.

Also, what are your credentials? You an ME with a background in dynamics? Your analysis seems focused on static loads.
The squat angle can be used to determine the resultant vertical force at the axle. Proof attached. This is standard in texts on vehicle dynamics.

Credentials? I don't have any. I'm a guy on the internet. I could tell you that I have a PhD. in suspension bicycle dynamics from MIT if I wanted.

Dynamics, when studied through a static medium like a computer page or page in a book, has to be done by comparing static situations at different instants in time.
 

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Trampelpfadbenutzer
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692 Posts
squish said:
I have a great idea guys. Instead of waisting our time with meaningless numbers and trying to prove that what ever "wonder linkage" is new and cool today has x amount more brake squat or bobs less than this thing overhere, or what ever the hell else. How bout we get off our butts, ride and let this whole subject fade away into the archive pages somewhere.
That is the best idea I have heard in a few weeks.

RaD
 

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Elitest thrill junkie
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lidarman said:
Gosh, being a physics kind of guy, I just want to huck my ride off a cliff and see if Newton's Laws still apply.

If Brake squat is a 1% effect on performance, does three times that really matter? I suppose so, if you focus on that part of it.
Depends on the situation. For overall riding, it may be 1%, if you are just tooling around or whatever.

On the real sketchy steep descent with lots of little bumps, you'll notice a much bigger difference, and it 3x that will be a huge difference.
 

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1946:2006:2066
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1,458 Posts
which linkage program?

I assume you are using Linkage 2.5 but which one? Personal or Professional.

Is the Professional worth the money?
It sounds like it might show all the forces you are describing.

michael
 

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The Ancient One
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1,573 Posts
Discussion Starter · #12 ·
mrdy said:
I assume you are using Linkage 2.5 but which one? Personal or Professional.

Is the Professional worth the money?
It sounds like it might show all the forces you are describing.

michael
I've just got the demo 2.5 plus the old free one. I'm thinking about buying one of them just to give him some money for his efforts.
 

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Steve from JH said:
I've just got the demo 2.5 plus the old free one. I'm thinking about buying one of them just to give him some money for his efforts.
Hey Steve,

Don't mention that the world is round. You'll have a lot of posters telling you that it doesn't feel that way. If it were round, they'd fall off the edge.... and that hasn't happened.... 'nuff said :rolleyes:
 

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...
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I feel robbed!

When I clicked on the thread I thought it was gonna be a bunch of CCs old bikes, maybe some more of those "spy photos" of his. Instead I got served up a heaping big pile of smelly diagrams, and some force vectors gibberish thrown in.

Why am I posting? "Move along nothing to see here folks" Time to go find a thread with some pictures... ;)
 

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What if Steve is saying the earth is flat, because he's quite clearly measured it to be so, and has diagrams to prove it? :)
 

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I was expecting bike pictures, too - I think the title was a little misleading. It should, at the very least, have contained the phrase 'brake squat' in it.
 

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Brass Nipples!
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2,006 Posts
Thanks Steve

Kinda sucks that you did all this work and all you're getting is crap. Reminds me a lot of the:

"Don't get an Ellsworth Truth it'll break."

"I've ridden my Truth for 5 years and had no problems."

"Doesn''t matter, I read they break a lot."

"Hey, don't respond to these posts and they'll go away."

"Yeah, I'm not responding to these any more."

"Me neither."

"Or me."

"Yeah, I propose we don't respond to these posts any more."

"OK."

etc. etc.

Thanks for figuring out what you could. I'm still waiting for the minimum braking distance test numbers.

People need to figure out that something in this topic must appeal to many, because of all the views and replies. I'm certainly getting tired of the discussions, but hey, I just posted too. :confused:
 

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1946:2006:2066
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1,458 Posts
I paid for the Personal Version.

Steve from JH said:
I've just got the demo 2.5 plus the old free one. I'm thinking about buying one of them just to give him some money for his efforts.
Mr. Kovacs definitely deserves something positive for his efforts.
Just as do you. Ignore all these MTB Turner ludites.

I'm thinking I might go for Mr. Kovacs' Professional Version.
Xmas present from me to me to Mr. Kovacs.

michael
 

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Steve from JH said:
T
Dynamics, when studied through a static medium like a computer page or page in a book, has to be done by comparing static situations at different instants in time.
In this context, then damping would be unimportant. Yes - you cannot easily show a dynamic system on a webpage, however the equations that take rotational inertia and damping into effect yield valid numbers more meaningful than the statics you describe. I am not trying to refute your analysis, just trying to understand it better.

Why is E and E' so far apart? Are these the actually pivot locations or something else? The geometry of the two systems seem much closer than the image suggests.

I wasn't giving you a hard time about your creditials, I just want to know what language to use. I am a post graduate engineering student with 8 years mechanical design experience so I can easily start talking about math that would get me banned from this forum so I want to know my audience before doing so.

Thanks for all the work on this. Whether or not it has any real-world relevance makes no difference to me. I like to ride...I like to derive...it's all sick.
 

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www.derbyrims.com
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Evidence to the contrary

Steve from JH said:
The squat angle can be used to determine the resultant vertical force at the axle. Proof attached. This is standard in texts on vehicle dynamics.

Credentials? I don't have any. I'm a guy on the internet. I could tell you that I have a PhD. in suspension bicycle dynamics from MIT if I wanted.

Dynamics, when studied through a static medium like a computer page or page in a book, has to be done by comparing static situations at different instants in time.
Having done some resent modeling of 4-bar suspension action, it is clear that the 4-bar configuration in your diagram produces forward rotation of the frame which would react as extending or anti-squat suspension action. There is in reality no squat reaction from applying the rear brake of that configuration, until the rear brake is released.

I'm sure you haven't done the modeling I've experienced or you wouldn’t hold on to the diagram as a “proof”.

Try cutting some stiff cardboard into 4 strips and use thumbtacks as pivot points similar to the configuration in the diagram. Rotate the “rear caliper link” forward and see what happens to the forward link (which the frame is fixed to). Hint: the IC shows which direction both the floating and fixed links rotate around. Hint#2: while the seat tube angles more forward, the rear suspension extends.

In the diagramed configuration how can there be rear suspension compression tension while the frame extends?

You should try it if you are really interested in facts. You would see that the angle of a and a’ in the diagram are clearly not calculating squat reaction, at least not for the 4-bar situation since the 4-bar actually extends the frame in that configuration.

- ray
 
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