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  1. #1
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    Relative Anti Squat Profiles Published! (finally)

    Thanks to a local engineer to helped my find the linkage program - here are a few anti squat profiles showing how ventana's stack up compared to a DW link and GT Idrive. These are just a few examples for refernce purposes only.
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  2. #2
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    Quote Originally Posted by iheartbicycles
    Thanks to a local engineer to helped my find the linkage program - here are a few anti squat profiles showing how ventana's stack up compared to a DW link and GT Idrive. These are just a few examples for refernce purposes only.
    Here's the ibis mojo...
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  3. #3
    The Bubble Wrap Hysteria
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    Not to discount your results or data but have you researched the credibility of the linkage program? Please post this so it will add credibility to your results.

  4. #4
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    Engineers, get a life and ride your bikes!!!
    Wait, first design some HVAC systems for me to inspect so I can keep working !!!

  5. #5
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    Quote Originally Posted by mtnbiker4life
    Not to discount your results or data but have you researched the credibility of the linkage program? Please post this so it will add credibility to your results.
    Nope! But I am glad you brought that up. I think a lttle scepticism is healthy. I do not vouch for the program, but it appears to be well accepted in the community. I would be interested to hear of any faults it may have.
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  6. #6
    on a routine expedition
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    Here's what Dave Weagle thinks of the Linkage program:

    Quote Originally Posted by dw
    It makes me cry to see people comparing bikes with that Linkage program. As you've pointed out, unless someone measured the bike with a CMM, there is NO WAY THAT THE INFORMATION IN THE PROGRAM IS ACCURATE.

    As a matter of fact, with short links like used on the Revolt, or a dw-link, a difference of 1mm makes a completely different bike. The pictures of leverage rate curves in this message are not accurate, and nobody should be basing anything off of them.

    Dave
    http://www.ridemonkey.com/forums/sho...&postcount=393

  7. #7
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    Help me understand. BTW, there is no disrespect, no baiting, no nothing hidden in this post.

    Ok, now maybe some of this was addressed in the "other post" here on the Ventana board, but once things started downhill, I tuned out. I'm not interested in a war of words, or suspension design. I've ridden Ventana a long time, and haven't ridden a lot of other designs, so ignorance maybe is bliss for me. Also, for me and my riding style, I personally haven't had anything to complain about with my Ventanas. Yes, I goof around with my suspension settings, both shock and fork, when I get something new, but then I'm generally happy.

    Ok, now that that is out of the way. Help me here -

    Squat. Is this sag? If not, what is the difference?

    Ok, so Ventanas, or the suspension designs similar to Ventana, squat(?) more than other designs in order to achieve full usage of the shock? (I'm asking, I don't know, but I think this is what I was reading on the other post.)

    Ok, so this (amount of needed) squat is bad? Again, I don't know, but it seems that it is from this discussion. Its bad because? Is it bad because in order to get full usage of the rear shock I need to sag or squat so far into the stroke that I lose (effective) travel?

    Ok, so for example, the suspension design of the day (and no doubt it is good, I have friends that are running it and love it), the DW, does not (need to) squat / sag as much, because of the frame design, so you are getting more usage of your over all travel? AND not "bobbing" as much, because your shock is not as soft???

    Assuming that my understanding thus far is correct, does a design that "sits higher" / less squat / sag, have any issues with what I think of as "top out". I mean, does this design (i.e. DW) require additional rebound control, or is this a non-issue. Again, I don't know the answer, I'm just trying to picture the various suspensions actively cycling in my mind.


    Thinking back over the past 20 years or so of mountain bike suspension styles, there have been some very interesting ones to be sure.

    I always love to learn when it comes to bicycles, and suspension design is one place I need to study.
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  8. #8
    Nightriding rules SuperModerator
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    one more thing...please use "print screen" to capture the screen (or Alt + PrnScn to capture only the active application) to the clipboard and paste it as a new image in your favorite image program, that would make them easier to read

    Thanks for the info

  9. #9
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    Quote Originally Posted by El Salt
    Help me understand. BTW, there is no disrespect, no baiting, no nothing hidden in this post.

    Ok, now maybe some of this was addressed in the "other post" here on the Ventana board, but once things started downhill, I tuned out. I'm not interested in a war of words, or suspension design. I've ridden Ventana a long time, and haven't ridden a lot of other designs, so ignorance maybe is bliss for me. Also, for me and my riding style, I personally haven't had anything to complain about with my Ventanas. Yes, I goof around with my suspension settings, both shock and fork, when I get something new, but then I'm generally happy.

    Ok, now that that is out of the way. Help me here -

    Squat. Is this sag? If not, what is the difference?

    Ok, so Ventanas, or the suspension designs similar to Ventana, squat(?) more than other designs in order to achieve full usage of the shock? (I'm asking, I don't know, but I think this is what I was reading on the other post.)

    Ok, so this (amount of needed) squat is bad? Again, I don't know, but it seems that it is from this discussion. Its bad because? Is it bad because in order to get full usage of the rear shock I need to sag or squat so far into the stroke that I lose (effective) travel?

    Ok, so for example, the suspension design of the day (and no doubt it is good, I have friends that are running it and love it), the DW, does not (need to) squat / sag as much, because of the frame design, so you are getting more usage of your over all travel? AND not "bobbing" as much, because your shock is not as soft???

    Assuming that my understanding thus far is correct, does a design that "sits higher" / less squat / sag, have any issues with what I think of as "top out". I mean, does this design (i.e. DW) require additional rebound control, or is this a non-issue. Again, I don't know the answer, I'm just trying to picture the various suspensions actively cycling in my mind.


    Thinking back over the past 20 years or so of mountain bike suspension styles, there have been some very interesting ones to be sure.

    I always love to learn when it comes to bicycles, and suspension design is one place I need to study.
    Actually if you tuned out Iheart and my discussion at the end, you missed out on some details on a killer Tahoe Ride...

    But first and foremost... No, Squat in the linkage program, is NOT Sag. Squat in this case is the force of the rider and bikes relative Center of Gravity moving backwards due to accelartion, causing the the suspension to compress ie Squat down. What I'm not sure about what the% means. But I'll assume the higher percentage number the more resistance to the "squat force" the linkage provide, what I don't know is percent of WHAT?

    Another concern along the lines of what Mtbk4life is bringing up, how were the numbers for the Geometry derived? I ask because I see a nearly 10mm error in the Salty #'s for the Chainstay alone. That's a 2% error to START with. Granted if that error is carried out thru ALL the frames the relative differences stay the same.
    EDIT : Not intended as critism or an attack, just trying to help in refining the numbers so they are more accurate.

    EDIT II : The main pivot of the rocker is shown placed BEHIND the seattube and the head angle is a steep 71.4 degrees. Iheart did you use a pre-2005 Salty?
    -A
    Last edited by Ciclistagonzo; 09-17-2009 at 04:20 PM.
    -Aaron G.

    "Before D.W., "anti-squat" was referred to as pedal feedback."

  10. #10
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    Quote Originally Posted by crisillo
    one more thing...please use "print screen" to capture the screen (or Alt + PrnScn to capture only the active application) to the clipboard and paste it as a new image in your favorite image program, that would make them easier to read

    Thanks for the info
    this software has security settings that don't allow this function.
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  11. #11
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    Worth Squat

    The rider's input to suspension performance cannot be measured by these plots- how he or she shifts body position and weight to get optimal performance. The best riders do not sit on their bikes like lifeless sacks of potatoes, they're dynamic and much less affected by these so-called theoretical limitations. The difference between the suspension system deemed "best" (whatever that is) and "worst" (ditto) is far less than the gulf separating a highly skilled pilot and even an average jockey.

  12. #12
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    Quote Originally Posted by Ciclistagonzo
    Actually if you tuned out Iheart and my discussion at the end, you missed out on some details on a killer Tahoe Ride...

    But first and foremost... No, Squat in the linkage program, is NOT Sag. Squat in this case is the force of the rider and bikes relative Center of Gravity moving backwards due to accelartion, causing the the suspension to compress ie Squat down. What I'm not sure about what the% means. But I'll assume the higher percentage number the more resistance to the "squat force" the linkage provide, what I don't know is percent of WHAT?

    Another concern along the lines of what Mtbk4life is bringing up, how were the numbers for the Geometry derived? I ask because I see a nearly 10mm error in the Salty #'s for the Chainstay alone. That's a 2% error to START with. Granted if that error is carried out thru ALL the frames the relative differences stay the same.
    EDIT : Not intended as critism or an attack, just trying to help in refining the numbers so they are more accurate.

    EDIT II : The main pivot of the rocker is shown placed BEHIND the seattube and the head angle is a steep 71.4 degrees. Iheart did you use a pre-2005 Salty?
    -A
    There aren't too many ventana's that have been plotted yet. THere is a 2007 Bruja showing the same antisquat as the 2005 salty. Being that pivot position is the same on the bikes (salty and bruja) and that antisquat is not a function of leverage ratio - I don't think it matters one way or the other.
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  13. #13
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    Quote Originally Posted by iheartbicycles
    Thanks to a local engineer to helped my find the linkage program - here are a few anti squat profiles showing how ventana's stack up compared to a DW link and GT Idrive. These are just a few examples for refernce purposes only.
    A few points of clarification.

    The numbers posted are all derived from a gear ratio of 32/30 - which I picked just cause it's a common climbing gear - but antisquat curves change based on gearing - so each bike will differ a bit based on this.

    Generally speaking, the lower the gear in the front - the more anti squat and the smaller (higher) the gear in the back, also the more antisquat. The converse holds true as well.

    Also - the anti squat posted for each bike is at top out - assuming sag of 20mm or so, each bike will behave a little differently. I haven't checked each - but of the ones I have (dw and ventana) antisquat decreases during suspension compression.
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  14. #14
    Nightriding rules SuperModerator
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    Quote Originally Posted by iheartbicycles
    this software has security settings that don't allow this function.

    bummer..I have the older version 2 and still allows it.....

    also..maybe the Alt+PrnScn may be blocked, but the one for the whole desktop should still work.... anyhow... too bad if it doesn't

  15. #15
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    Quote Originally Posted by Marshall Willanholly
    Here's what Dave Weagle thinks of the Linkage program:



    http://www.ridemonkey.com/forums/sho...&postcount=393
    That doesn't appear to be an indictiment of the program as much as the users. As the saying goes "garbage in, garbage out."
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  16. #16
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    Quote Originally Posted by Ciclistagonzo
    Actually if you tuned out Iheart and my discussion at the end, you missed out on some details on a killer Tahoe Ride...

    . What I'm not sure about what the% means. But I'll assume the higher percentage number the more resistance to the "squat force" the linkage provide, what I don't know is percent of WHAT?


    -A
    I believe it's a percentage of inertia. If you know the bike is accelerating at a certain rate you can configure the initertia of the bike and it's rider. My guess is antisquat % posted is the resistance to this.

    The error I see in this is you can't assume 100% antisquat means the bike is 100% efficient because it doesn't take into account the rider is not a perfect machine - in addition to the downward force on the pedals, (and we all do this) we all have a tendancy to bounce a bit as we pedal. So even a bike with 100% antisquat will bob a bit. More anti squat is required to counter the effects of inertia combined with rider induced bob.

    This is just my guess/understanding.
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  17. #17
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    Quote Originally Posted by iheartbicycles
    I believe it's a percentage of inertia. If you know the bike is accelerating at a certain rate you can configure the initertia of the bike and it's rider. My guess is antisquat % posted is the resistance to this.

    The error I see in this is you can't assume 100% antisquat means the bike is 100% efficient because it doesn't take into account the rider is not a perfect machine - in addition to the downward force on the pedals, (and we all do this) we all have a tendancy to bounce a bit as we pedal. So even a bike with 100% antisquat will bob a bit. More anti squat is required to counter the effects of inertia combined with rider induced bob.

    This is just my guess/understanding.
    That is what i assumed as well, but wanted to hear what others thought. I agree with your assesment about how we as rides are a dynamic being and are not a static force on our bikes. There is no 100% "efficient" design.

    Any idea HOW anti-squat is plotted by the program? I'd like to see the equation(s)

    Edit: Or a link to the program?

    -A
    -Aaron G.

    "Before D.W., "anti-squat" was referred to as pedal feedback."

  18. #18
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    Quote Originally Posted by Ciclistagonzo
    That is what i assumed as well, but wanted to hear what others thought. I agree with your assesment about how we as rides are a dynamic being and are not a static force on our bikes. There is no 100% "efficient" design.

    Any idea HOW anti-squat is plotted by the program? I'd like to see the equation(s)

    Edit: Or a link to the program?

    -A
    http://www.bikechecker.com/
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  19. #19
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    Do you have any...

    Diddley Squat profiles plotted?
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  20. #20
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    As a lay-reader and not a mechanical engineer..

    While this is an interesting discussion, what are we supposed to take away from this? We all need Propedal or some type of compression to offset the squat? I mean, it comes across like iheartbicycles is trying to prove something about the DW link being so much better than the Ventana designs, and not necessarily using current Ventana designs. I just can't figure out what I'm not being snarky, just want to understand the point you're trying to get across.

    Do you take into account any of the newer designs like the Bruja v2 or the Terremotto? What about running the bike with 30% sag (Sherwood recommends 30%) instead of 25% sag? Would that have an effect on the squat?

    I just ride bikes, not design 'em
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  21. #21
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    Quote Originally Posted by Stripes
    As a lay-reader and not a mechanical engineer..

    While this is an interesting discussion, what are we supposed to take away from this?
    This is simply a follow up on the many other threads where people have asked why their Ventana's squat so much while pedalling. Usually the people on the Ventana board recomend high levels of propedal and etc. This fix doesn't always work for one, and makes the suspension less active. When I brought up the idea that the suspension design itself was at fault, lacking in sufficient antisquat, it turned into an argument. So here you go.

    I like objective over subjective and empirical over ethereal. If after understanding this information you still love your ventana, that is fine - but this is the information I wanted to add to the conversation

    Quote Originally Posted by Stripes
    We all need Propedal or some type of compression to offset the squat? I mean, it comes across like iheartbicycles is trying to prove something about the DW link being so much better than the Ventana designs
    all the designs I checked had significantly more anti squat than the ventana. The GT Idrive actually had the most. Of the Idrives, the DHI had the most (200%)

    ,
    Quote Originally Posted by Stripes
    and not necessarily using current Ventana designs.
    Ventana has never changed their anti squat profile. Being that the bike is a single pivot and that the pivots are in the same place from year to year - plotting a 2005 vs a 2009 doesn't matter. But just in case, I did go and check on a 2007 and it has the same antisquat.


    ,
    Quote Originally Posted by Stripes
    Do you take into account any of the newer designs like the Bruja v2 or the Terremotto? What about running the bike with 30% sag (Sherwood recommends 30%) instead of 25% sag? Would that have an effect on the squat?

    I just ride bikes, not design 'em
    Yes, I did check one of the newer designs. The changes to the newer designs don't affect antisquat - they affect compression curves.

    With the Ventana's at 30% sag their antisquat decreases from an already low 45% to an even lower 37%.
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  22. #22
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    Quote Originally Posted by Marshall Willanholly
    Here's what Dave Weagle thinks of the Linkage program:



    http://www.ridemonkey.com/forums/sho...&postcount=393

    The program is 100% Accurate, the only problem is that pictures are not, they are always a little bit distorted, so the models are not perfect. If a bike has very small links the miskake is bigger, but it really depends on the picture that you are using to do the Linkage Model.

    If you use a "Full HD" picture, or a CAD Drawing you can build a very good model.

    I'ld love to see this kind of stuff posted by the original authors, and see how big are the mistakes that we are making but they never give this kind of information (Banshee is probably the only exception...). In the meantime, I'll keep using the program.

  23. #23
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    I've been riding a DW for the past 9 months and kinda miss the squat action of the Ventana under pedal load and braking. I like what it does to the geometry and handling of the bike. And on tech climbs the squat is not an issue. It's the long steep climbs where you have to remain on the nose of the seat for a while that bug.

  24. #24
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    Say(ing) what?

    There definitely is some bob going on with my plush X5, and on long flat climbs often I crank up some propedal and even lockout the Pike. The shock and fork don't seem to get warm so I doubt any significant amount of energy is being converted to heat. I do get a lot less beat up & rattled than some of my virtual pivot friends on high speed washboards and fast downhill rocks (e.g. Baldwin, Rocky Ridge). Also, I believe the compliance helps get up and over things nicely sometimes (nicer than my virtual buds). Haven't had the pleasure of a direct comparison ride w/ a DW, just w/VPP.

    Like Stripes, I'm still waiting for a direct statement of meaning from all this analysis. Are you saying a Ventana design wastes energy that a DW doesn't, or that it rides worse or harder under certain conditions, or doesn't climb well? Come on, we can handle the "truth" (as you see it).
    K

  25. #25
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    Quote Originally Posted by bayareamtnbiker
    There definitely is some bob going on with my plush X5, and on long flat climbs often I crank up some propedal and even lockout the Pike. The shock and fork don't seem to get warm so I doubt any significant amount of energy is being converted to heat. I do get a lot less beat up & rattled than some of my virtual pivot friends on high speed washboards and fast downhill rocks (e.g. Baldwin, Rocky Ridge). Also, I believe the compliance helps get up and over things nicely sometimes (nicer than my virtual buds). Haven't had the pleasure of a direct comparison ride w/ a DW, just w/VPP.

    Like Stripes, I'm still waiting for a direct statement of meaning from all this analysis. Are you saying a Ventana design wastes energy that a DW doesn't, or that it rides worse or harder under certain conditions, or doesn't climb well? Come on, we can handle the "truth" (as you see it).
    K
    My direct statement I thought was pretty clear. This thread is really a follow up to numerous other threads.

    The only thing I would add is the shocks spec'd on Ventana's generally are either the medium or high compression tune RP23's - which have significanty more compression than those spec'd on many other bikes. You will not achieve a more plush ride on a Ventana due to this, alone.

    Please note that I have included info on many non-dw bikes. The Idrive is notable as with regard to antiquat - it is a single pivot.

    I also ran numbers on Foes FXR - which came in at more than 100% antisquat for a simple, single pivot.
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