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  1. #1
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    Rear Shock - How does it work?

    Hi all,

    Bought a used 05 Specialized Epic Comp Disc - the previous owner was trying to describe how the whole "Brain" thing worked but I'm not getting it. When I ride it seems almost like a hardtail - I really can't even tell there is any compression at all. I understood that it somehow reduces the "bouncy bouncy" when you pedal ... right?

    Please tell me:

    1 - what's the concept of the "Brain" - how does it work?

    2 - how can I test to see if my shock is even working? If I dismount and simply lean heavy on it it won't budge.

    Thanks!

  2. #2
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  3. #3
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    to test the brain, lift up the rear of your bike with your seat and then slam it down and lean on the seat in 1 motion. Your brain will activate and the shock compress. Or just put a cable tie around the piston, push it up against the seal and do a bunny hop to activate the brain

  4. #4
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    Thank you for the video link and test - that helps!

    A couple more questions, please.

    1 - brad72 - when I do as you describe it works ... for one compression. Any further attempts to compress the shock, without again slamming it, are in vain. Normal?

    2 - I noticed in the video that, with an adjustment, the shock could be set to appear to bypass the brain - in that the shock could be compressed easily with a push on the seat. Is that exclusive to the "Fade" technology? My 05 with the "Lite" won't have that adjustment will it? As mentioned above it literally takes a slam to get any sort of compression regardless of any adjustment to the thumb wheel.

    Thanks again!

  5. #5
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    Regarding the compression yes, it will usually compress once then return.

    Heres what you do. Push the o'ring on the shock piston up to the dust seal. Sit on the bike in your normal riding gear and let the rear shock settle for about 10 seconds. Carefully get off the bike and measure the sag. On my 2006 epic I ran about 13mm of sag, that is the distance from the dust deal to the o'ring. Longer than 13mm add air, shorter than 13mm let some air out. Once this is done you can set how firm of soft the shock will be via the dial on top of the shock. Really this dial just governs how big of a bump is required to make shock active. But once the shock has gone through it's cycle and rebounded it will need another hit to become active again. That why you can pedal with a hardtail type platform till a bump is hit.

    Rebound setting is a personal thing. Good starting point is in the middle of the number of available clicks, then adjust from there. To fast a rebound and it will feel like the bike is trying to buck you, too slow and it will bottom out and just feel like crap
    Last edited by brad72; 10-15-2010 at 03:05 AM.

  6. #6
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    Thanks for that info, brad72 - greatly appreciated!

    The o-ring was not present - maybe had deteriorated or broken. I went to the hardware store and got a few - removed one end of the shock and replaced the o-ring. Once that was in place I was able to set it up as you describe. I seem to have it dialed in but will test tomorrow on an actual ride.

    One quick question - is there an exploded view/parts breakdown somewhere for that model? When I took the shock off I wasn't paying close enough attention and 3 washers fell. I "think" I know where they came from but ...

    also what is the torque spec on the upper shock bolt?

    Thanks again!

  7. #7
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    Try the specialized web site. It may have something for you. I found an owners manual PDF for an XC with exploded views. Hope this helps.http://www.specialized.com/us/en/bc/...Name=downloads
    Disclaimer: Always get a second opinion cause I'm just guessing

  8. #8
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    Thanks - I did find the schematic here.

    Should be good to go!

    Thanks everyone!

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