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  1. #1
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    6Pack+Wires=New Toy (Techno-geeks only)

    Howdy,

    Came back from I-Bike and had a package from Paul over at Race Tech on my desk. What was in it? His latest leverage ratio/wheel travel analysis package. Let the fun begin.

    One 6 Pack, a few wires, a few minutes of my time, and voila!

    157mm (6.2") of vertical wheel travel (shock metal to metal) and a 5.7% rising rate over the bulk of the stroke.
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  2. #2
    Rolling
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    Cool...sexxay.

    This is like doing it with porn on the tv!

  3. #3
    Amphibious Technologies
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    Quote Originally Posted by PUSHIND
    157mm (6.2") of vertical wheel travel (shock metal to metal) and a 5.7% rising rate over the bulk of the stroke.
    Awesome! Nice to know I'm getting 6" of actual travel.

    So what does the 6% rising rate over the bulk of the stroke mean (please translate in plain English)? Will this info affect how you tune the shocks from now on?

    Looking at the leverage ratio dot plot, it seems like the ratio actually remains the same throughout the travel; i.e. no statistically significant change. If so doesn't that mean that the leverage rate is linear?
    Last edited by SCUBAPRO; 10-11-2005 at 04:33 PM.
    "The best you've ridden is the best you know" - Paul Thede, Race Tech

  4. #4
    Natl. Champ DH Poser/Hack
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    who ya got runnin that thing? jordi la forge? guessin the box on the down tube holds the dilythium crystals.
    No, I'm NOT back!

  5. #5
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    Darren,
    Does that information suggest that one setup will be better for the 6 pack than another,ie an Air or a Coil, or is 5.7 % not the factor, both air and coil can be tuned to suit.
    Thanks

  6. #6
    FM
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    Yeah, while you're at it, can you explain the whole "regressive travel" thing in regards to running a 2.25" stroke shock on the RFX/6-pack?

  7. #7
    Yay! Bikes !
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    Quote Originally Posted by FM
    Yeah, while you're at it, can you explain the whole "regressive travel" thing in regards to running a 2.25" stroke shock on the RFX/6-pack?
    BIG ditto. I'd love to know.

    coughcoughcough.avyforxmas.coughcoughcough
    Nick.

  8. #8
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    So what does the 6% rising rate over the bulk of the stroke mean (please translate in plain English)? Will this info affect how you tune the shocks from now on?

    Looking at the leverage ratio dot plot, it seems like the ratio actually remains the same throughout the travel; i.e. no statistically significant change. If so doesn't that mean that the leverage rate is linear?
    It means that the suspension between sample points has a rate change of (+) 6%. This means that the suspension rate rises to help increase bottoming resistance toward the end of the stroke. Higher initial leverage for better small bump compliancy, Lower ending number to help in bottoming control. As for the plot, it shows a plot of the rate rise throughout the entire stroke. Note how the left side of the plot is higher than the right side (Rising Rate), not linear. Lastly, we've yet to tune dampers for the 6 Packs at the consumer level, so there would be no changes.


    who ya got runnin that thing? jordi la forge? guessin the box on the down tube holds the dilythium crystals.
    You may laugh, but I actually had to Google that name to find out what you were talking about!


    Does that information suggest that one setup will be better for the 6 pack than another,ie an Air or a Coil, or is 5.7 % not the factor, both air and coil can be tuned to suit.
    Not necessarily, however I'm a fan of the coil personally.


    Yeah, while you're at it, can you explain the whole "regressive travel" thing in regards to running a 2.25" stroke shock on the RFX/6-pack?
    I'm not familiar with the "regressive" term in regards to suspension? Running a 7.875 x 2.25" stroke on a DHX I'm sure would produce a number of geometry issues, both in suspension and chassis though. It would change the starting and ending angles of the rockers which would alter the leverage ratio significantly as well as change the BB and HA of the frame.

    Darren

  9. #9
    Elitest thrill junkie
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    Quote Originally Posted by PUSHIND

    I'm not familiar with the "regressive" term in regards to suspension?
    Suspension can be regressive, digressive, linear, or progressive.

    Regressive=Amount of force required to compress an inch is increasing as it goes through travel, except for each inch, it's a lesser amount of force. A regressive curve will reach a point at which it begins to become digressive. So to compress one inch might take 400lbs, to compress another inch will take 500lbs, to compress another inch will take 450lbs, if the curve continues it will approach linear, and the start to digress, which will be "falling rate". Some bikes can have a regressive spring curve, and they run out of travel before it gets "linear" or "falling rate".

    Digressive=Amount of force required to compress an inch is less as travel is increased.

    Lastly, the problem with putting a longer stroke shock on many bikes, linkage or otherwise, is that if you could keep increasing the stroke of the shock, maintaining the same eye to eye (or even slightly different) you'd reach a point where the suspension would become a falling-rate, because the eyelet hole of the linkage will eventually start to move away from the eyelet hole of the frame. This means the rate of the suspension is changing past what it was designed with, so, with 6" of travel a certain bike might have a linear or progressive rate, and when you increase travel by increasing the stroke of the shock the suspension starts to get either regressive or digressive, in not as many words it's a good way to screw up your suspension and run into a plethora of other problems.
    Last edited by Jayem; 10-11-2005 at 08:38 PM.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  10. #10
    FM
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    Darren, thanks for posting back!

    The "regressive" thing came up here: in regards to pushing a 7.5x2.25" fox vanilla RC for use on a RFX or 6-pack. I was curious about it since I got the push factory race system done on my 7.5x2.25 vanilla RC. With 6" rockers, this produces an extra 3/4" of travel, compared to the stock 7.5x2.0" shock. I'm asking about it here, because I was curious why Bulldog and I got different stories about your willingness to service the 7.5x2.25 vanilla. Perhaps this was all a miscommunication.

    A bunch of us with RFX's have played with this and found that a few diferrent rocker designs were produced for the RFX, some have tire clearance issues with the 7.5x2.25 shocks and others don't. yeah, we have kind of a shock cult going on.

    For the record, my set-up works great. Plenty of tire clearance with michelin DH 2.5's, the shock does not bob, or bottom out on flat landings. It's seen moab, whistler and plenty of north vancouver this year on top of the local seattle rides, so I've put it through the paces. If anything, I think it could benefit from slightly less compression damping. I do much prefer the pushed 2.25" RC to the other shocks I have had on this bike (fox RP3 and romic). Not to mention, I really appreciated the time you and Jimmy spent with me on the phone. Good stuff!



    Quote Originally Posted by PUSHIND
    I'm not familiar with the "regressive" term in regards to suspension? Running a 7.875 x 2.25" stroke on a DHX I'm sure would produce a number of geometry issues, both in suspension and chassis though.

  11. #11
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    Regressive=Amount of force required to compress an inch is increasing as it goes through travel, except for each inch, it's a lesser amount of force
    ?? uh...okay

    All I know is that I've been involved in suspension design and engineering for more than 10 years proffesionally now, and neither myself nor my colleagues have ever used that term.

    Suspension systems can be Falling, Rising, or Linear. Damping curves can be Linear, Digressive, or Progressive.

    Suspension design:
    Falling = Leverage increases as the suspension compresses
    Rising = Leverage decreases as the suspension compresses
    Linear = Leverage maintains a constant value as the suspension compresses

    Damping curves:
    Linear = Damping force increases proportionate to velocity
    Digressive = Aggressive initial damping values followed by a sharp leveling where damping value remains the same no matter how much the velocity is increased.
    Progressive = Damping curve where force increases are disproportionate to velocity.

    This remains true whether Motorsport or bicycle.

    Darren

  12. #12
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    Oh yeah

    FM,

    Now it's clear. As for the RFX thing, we had/have some conflicting results/data that prevent us from moving forward with that setup. As for your bike, or others that we've set up in the past, we'll still continue to offer service/support.

    Again, it's just not an application that we feel comfortable releasing. It's a great application for an Avalanche unit though.

    Thanks,

    Darren

  13. #13
    FM
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    Awesome, thats exactly the short of clarification I was hoping for.

    So basically, no problems pulling extra travel out of the RFX using a 2.25" stroke shock, but the old vanilla RC may not be the best candidate due to it's design limitations. (i'm guessing lack of oil volume, etc) Makes me think: perhaps this is why fox quit making this weird size to begin with!

    I think it's awesome when the people behind the products (like yourself or Dave Turner) hop on the boards here to clear stuff like the up in person- thanks again.

    Quote Originally Posted by PUSHIND
    Again, it's just not an application that we feel comfortable releasing. It's a great application for an Avalanche unit though.

    Thanks,

    Darren

  14. #14
    ... I guess you won't be
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    I'm wearing new socks!!!
    Yes, we do indeed rock...http://www.myspace.com/spokedrunkies

  15. #15
    Rolling
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    Quote Originally Posted by PUSHIND
    ?? uh...okay

    All I know is that I've been involved in suspension design and engineering for more than 10 years proffesionally now, and neither myself nor my colleagues have ever used that term.
    ...
    It's ok Darren, some homers might have the word "regressive" in their head since Dave dropped the bomb on them....besides, maybe they got lost in your linear regression fit on that data.

  16. #16
    Elitest thrill junkie
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    Quote Originally Posted by PUSHIND
    ?? uh...okay

    All I know is that I've been involved in suspension design and engineering for more than 10 years proffesionally now, and neither myself nor my colleagues have ever used that term.

    Suspension systems can be Falling, Rising, or Linear. Damping curves can be Linear, Digressive, or Progressive.

    Suspension design:
    Falling = Leverage increases as the suspension compresses
    Rising = Leverage decreases as the suspension compresses
    Linear = Leverage maintains a constant value as the suspension compresses

    Damping curves:
    Linear = Damping force increases proportionate to velocity
    Digressive = Aggressive initial damping values followed by a sharp leveling where damping value remains the same no matter how much the velocity is increased.
    Progressive = Damping curve where force increases are disproportionate to velocity.

    This remains true whether Motorsport or bicycle.

    Darren
    How would you describe each of these then?

    One the first one, it goes from ~linear to falling rate.

    The second one is linear, the amount of force to compress an additional inch is always the same.

    On the third one the amount of force to compress an inch is increasing with travel, but the rate at which it is increasing is actually decreasing. This is key to describing what we are talking about. If you don't believe there are bikes that share this trait, you need to do some more research.

    The fourth one is progressive, the amount of force required increases with each additional inch.
    Attached Images Attached Images
    Last edited by Jayem; 10-12-2005 at 09:28 AM.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  17. #17
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    Quote Originally Posted by PUSHIND
    ?? uh...okay

    All I know is that I've been involved in suspension design and engineering for more than 10 years proffesionally now, and neither myself nor my colleagues have ever used that term.
    Darren, Jayem has his own terminology for everything, and he seems to trust and rely on a linkage program that he takes as gospel that isn't quite right.

  18. #18
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    What is it?

    This is key to describing what we are talking about
    Who is "we"

    you need to do some more research.
    That's what we do everyday here at PUSH. That's why this whole post exists. There is an astronomical amount of time, money and energy being put into this equipment and we take what we do very seriously.

    At this point I feel like your comments aren't meant to be constructive, but rather to attack either myself or my company. In your post you don't provide the information to whether your lines are for leverage rates or damping curves, in either case your infromation describing them is incorrect.

    I would be curious as to your profession, but it appears that you work in the industry?

    Darren

  19. #19
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    Hey Darren,
    Can I get some of those cool PUSH stickers for my car?

  20. #20
    It's a Turner!
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    Do you have any experience with the new Cane Creek Double Barrel shock? http://www.canecreek.com/46.html

    Interested to see how this shock performs on a 6-Pack.

    Quote Originally Posted by PUSHIND
    FM,

    Now it's clear. As for the RFX thing, we had/have some conflicting results/data that prevent us from moving forward with that setup. As for your bike, or others that we've set up in the past, we'll still continue to offer service/support.

    Again, it's just not an application that we feel comfortable releasing. It's a great application for an Avalanche unit though.

    Thanks,

    Darren
    I didn't just drink the koolaid, I stuck my head in the punchbowl.

  21. #21
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    Decals

    sumguy1,

    Drop an e-mail to christina@pushindustries.com. Get her a name and mailing address and she'd be happy to get you setup. We have a new decal sheet that has like 25 different pieces on it.

    Darren

  22. #22
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    Quote Originally Posted by PUSHIND
    I would be curious as to your profession, but it appears that you work in the industry?

    Darren
    Doesn't being a 28 year old bike shop owner qualify one as a suspension specialist?

  23. #23
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    Do you have any experience with the new Cane Creek Double Barrel shock
    No but I did have it's big brother, the Ohlins TTX40 in for an application last year. I have huge respect for Ohlins, but have no experience with the Cane Creek unit. It doesn't seem like there are many out there.

    Darren

  24. #24
    Now with flavor!!
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    Thanks for posting. Neat stuff.

  25. #25
    Rolling
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    Quote Originally Posted by Jayem
    H
    On the third one the amount of force to compress an inch is increasing with travel, but the rate at which it is increasing is actually decreasing. This is key to describing what we are talking about. If you don't believe there are bikes that share this trait, you need to do some more research.

    .
    I think there is an issue here with terminology. Darren probably lumps this under the general term of rising rate since even though it's not linear, it's still rising. Your terminology seems to originate from the regressive tax idea the tax rate decreases as income increases. I suppose you can use this terminology here but is it really used in the industry?

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