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  1. #1
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    Air shocks more active in initial travel ?

    Are air shocks more active in their initial travel compared to coil shocks ?

  2. #2
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    Ummm...no not really, but...

    the modern crop of air shocks are pretty darned close anymore. But a coil shock is still more active or responsive to small hits, stutter bumps etc. A few years back, coils were hands down favorites for small hit compiance. That was due to the initial stiction (stickieness) or resistance to initial movement that is inherent in air shocks/forks. This has been over come by the addition of "negative air chambers" or "negative springs" to most air shocks and forks. This is a small chamber or spring that acts against the main airchamber in order to overcome stiction. Almost all air shocks use some form of negative chamber anymore. Many of Rock Shox offerings have the capability of seperate negative air adjustment, you manualy pump up the negative chamber with a pump just like the main chamber, "Dual Air" they call it. The higher you set the pressure (up to a point) in the negative chamber, the more active the shock will be. I don't know for sure how Fox and Cane Creek do it, but as you pump up the main chamber, air is added to the negative chamber using a predetermined (set at the factory) ratio. Either way it works pretty well, Anyway, a properly set up and sprung coil shock still reacts better to small hits than an air shock. But, a modern air shock, properly set up and adjusted will come VERY close to the same performance as a coil, with the added advantage of being highly resistant to bottom out, and a much wider range of adjustment for rider weight without resorting to the purchase of a lighter or heavier spring.

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  3. #3
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    I ran a Pushed Vanilla air shock on an Enduro that suffered from horrible pedal bob. Not sure if it was the horst link or the air shock - ran a non-platformed coil on the same bike and had far less pedal bob ?

  4. #4
    Bodhisattva
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    Quote Originally Posted by keen
    I ran a Pushed Vanilla air shock on an Enduro that suffered from horrible pedal bob. Not sure if it was the horst link or the air shock - ran a non-platformed coil on the same bike and had far less pedal bob ?
    Keen,
    This doesn't make sense.
    Vanillas, both front & rear, are coil shocks.
    The Float/RP3/AVA, etc are air shocks.
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  5. #5
    www.derbyrims.com
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    To the original question....
    There is more "plushness" with air in midstroke compared to a coil with the same overall travel on the same bike.

    With the same total travel, sag level, and damper settings, air springs ramp up compression resistance much later in travel, so are softer in mid stroke.

    Even with the advances of slicker sliding, negative sprung, more linear air shocks and forks, coil still has much freer action over very small bumps, this is the traction advantage.

    - ray

  6. #6
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    Quote Originally Posted by The Squeaky Wheel
    Keen,
    This doesn't make sense.
    Vanillas, both front & rear, are coil shocks.
    The Float/RP3/AVA, etc are air shocks.

    Oops meant Pushed Float...

  7. #7
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    Derby - question

    Quote Originally Posted by derby
    To the original question....
    There is more "plushness" with air in midstroke compared to a coil with the same overall travel on the same bike.

    With the same total travel, sag level, and damper settings, air springs ramp up compression resistance much later in travel, so are softer in mid stroke.

    Even with the advances of slicker sliding, negative sprung, more linear air shocks and forks, coil still has much freer action over very small bumps, this is the traction advantage.

    - ray
    Derby, given what you have said, would'nt that also mean the intial shock movement would be more active.
    For example: the first .5" of shaft travel would have a much lower ramp up as compared to a coil. As the volumn decreases the pressure increases exponentially, but this also has a positive effect in the beginning of the shock travel as the increase in compression is not as fast as a coil spring, Right?
    The early shocks might have had issues with sticktion, but not in a few years. Also, even coil shocks have high psi of nitrogen.

    Derby thanks for all the great posts in the past, keep them coming!

    Thanks,
    Phil

  8. #8
    Elitest thrill junkie
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    Quote Originally Posted by Phantomtracer
    Derby, given what you have said, would'nt that also mean the intial shock movement would be more active.
    No, the large shaft on an air shock has a large surface area where the seal contacts the shaft, and it creates much more friction than you'll get in a coil shock, where the seal doesn't have to be nearly as strong because it's only holding in oil around a relatively small shaft. This phenominon is known as "stiction" and it is why the air shock is not as compliant over small bumps. Stiction is still there, and it's still noticable. The air shock will tend to not move over very small impacts, causing the rear end of the bike to just not react to small bumps, so it's not as active as the coil shock.

    I noticed this on the DHX-air, but it's a very small effect. The fact that the shock wants to blow through it's mid-stroke travel can almost mask this effect, but I can still feel it on the small bumps. Not bad these days, but still noticable.

    The higher the leverage ratio, the less this may be apparent, but if air shocks were great at having better initial compliance, we'd see them more on baja racers and other areas where suspension compliance is the #1 priority.
    Last edited by Jayem; 11-01-2005 at 08:43 PM.
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  9. #9
    TNC
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    Good question.

    Quote Originally Posted by Phantomtracer
    Derby, given what you have said, would'nt that also mean the intial shock movement would be more active.
    For example: the first .5" of shaft travel would have a much lower ramp up as compared to a coil. As the volumn decreases the pressure increases exponentially, but this also has a positive effect in the beginning of the shock travel as the increase in compression is not as fast as a coil spring, Right?
    The early shocks might have had issues with sticktion, but not in a few years. Also, even coil shocks have high psi of nitrogen.

    Derby thanks for all the great posts in the past, keep them coming!

    Thanks,
    Phil
    I've been running some high end air and coil shocks (5th E coils, DHX coil, Manitou 4-Way Air) over the last couple of years on my long travel bikes...6" and greater. It's gotten darned near impossible to tell which type is plusher in that intial travel at the appropriate sag postition and somewhat at full extension. I think there is a tiny bit of noticeable plushness advantage in the coil version when coming off of full extension, but the shock doesn't operate at this postion except in those situations where your suspension is cycling in very harsh terrain during compression and full extension...and ultrasoft minute measurements of plushness at this point are usually not a problem. These later air and coil shocks might need some kind of sensitve measurement device to detect the minute differences of plushness between them...a kind of "Plushometer"...LOL! This difference might also be more noticeable in shorter stroke shocks vs. longer stroke models. It seems these longer eye-to-eye and longer stroke air shocks have more air volume, less initial setup pressures, and this may be what I'm making my assessment on. I don't have any air shocks less than 7.875 X 2.0. Another factor might also be the particular bike design that any particular shock is installed on. Different designs excert different demands on different shocks to some degree, therefore the feedback can be different.

    On your mention of nitrogen in today's coil shocks, the 5th E coils and DHX coils don't have a nitrogen charge anymore. I just found that out myself a few months ago. All done with air now.

  10. #10
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    Quote Originally Posted by The Squeaky Wheel
    Keen,
    This doesn't make sense.
    Vanillas, both front & rear, are coil shocks.
    The Float/RP3/AVA, etc are air shocks.
    Not that he meant it, but there actually was a Vanilla Air back in the early days. I think it came right after the first Fox MTB shock, the Fox Alps.

  11. #11
    TNC
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    Showing your age?

    Quote Originally Posted by DtEW
    Not that he meant it, but there actually was a Vanilla Air back in the early days. I think it came right after the first Fox MTB shock, the Fox Alps.
    LOL!...I had a '96 Trek Y-33, and I recall seeing, I believe, the Y-22 with one of these Fox Vanilla air shocks. Anyway, the shock I recall even had a piggyback. Looked pretty cool, but I'd bet by today's standards it would feel like poo.

  12. #12
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    Quote Originally Posted by TNC
    LOL!...I had a '96 Trek Y-33, and I recall seeing, I believe, the Y-22 with one of these Fox Vanilla air shocks. Anyway, the shock I recall even had a piggyback. Looked pretty cool, but I'd bet by today's standards it would feel like poo.
    Check out what I found going in my old magazine stash. This is a full-page ad from the October 1998 issue of MBA. I guess FLOAT was acutally an acronym, at least it started out that way. The Float forks do not use an air negative spring, although the Float shocks still do.
    Attached Images Attached Images

  13. #13
    Bodhisattva
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    Great post. Thanks for the trip down memory lane.
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