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  1. #1
    Formerly of Kent
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    SID Brain 9mm 29er SA - Conversion Options?

    As the title says, I am looking at a SID Brain. 9mm, 29er, Solo Air.

    Right now I'm running an RCT3 Dual Air 15mm.

    Love the 15mm TA. Not going back to 9mm.

    So, what are the options for a Frankenstein fork?

    DA lowers with SA Brain upper?

    Swap dampers? Is that possible?

    Buy new 15mm SA lowers for the SID Brain?


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    Last edited by Le Duke; 1 Week Ago at 07:13 PM.

  2. #2
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    Just swapping Dampers is the easiest. But is going to involve removing the lower from the upper anyhow.

    If the Specialized fork has a carbon crown, I would put the QR15 lowers on that and swap the damper.

    If it's an aluminum crown/steerer I would just put the Brain damper in your QR15 fork.

    Just take your time and have some appropriate weight fork fluid on hand. Keep everything nice and clean and well organized. You don't have to have extra O-rings laying around after reassembly It's not that bad.

  3. #3
    Formerly of Kent
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    Quote Originally Posted by briscoelab View Post
    Just swapping Dampers is the easiest. But is going to involve removing the lower from the upper anyhow.

    If the Specialized fork has a carbon crown, I would put the QR15 lowers on that and swap the damper.

    If it's an aluminum crown/steerer I would just put the Brain damper in your QR15 fork.

    Just take your time and have some appropriate weight fork fluid on hand. Keep everything nice and clean and well organized. You don't have to have extra O-rings laying around after reassembly It's not that bad.
    Briscoelab,

    Thanks for the response. I do all of the work on my forks and shocks, so I'm well versed in the workings of RS forks.

    However, it sounds like the Brain unit is different than what I'm used to working on, in that it is more a one-piece cartridge unit, similar to Fox forks. I don't envision this being a problem, I'm just not familiar with it.

    My original plan was to just swap the Brain into the RCT3 fork, as suggested.

  4. #4
    J-Flo
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    Le Duke,

    I had a very similar situation a few months ago -- I have a SID WC Brain fork with 9mm QR and I hated the thought of losing my 15mm TA. I was all set to buy new lowers for the fork in order to get the 15mm TA but decided to try the 9mm QR with 28mm end caps, which was good enough for the race team until a year ago, and a fellow at Specialized said the switch to 15mm TA across the board was primarily driven by marketing (desire to offer the perceived new standard and to abandon the custom 28mm end cap spec). I wasn't sure I believed it but I do now. I was surprised by how stiff the 9mm with 28mm end caps is when tightened down well with a good ratcheting QR. The front end stability is indistinguishable to me from my son's bike, which is a 2014 model with the same fork and 15mm TA.

    it might work to swap dampers with your existing RCT3 if you prefer to go that route, but I fear it might not because the lowers were slightly redone when they switched from Dual Air to Single Air and the other specs (damper rod length, mounting position of the rebound knob, etc.) may not be exactly the same. The oil volume is not the same, for example. As long as the total internal length of the lower on your older RCT3 fork is exactly the same, it should work -- you will need to swap out all the damper side parts, as the Brain is a cartridge style unit rather than an open-bath damper. Rockshox should be able to confirm this.

  5. #5
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