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  1. #1
    NRS
    Reputation: nygeo's Avatar
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    definitive NRS seatpost diameter?

    I am about to buy a thomsom seatpost for my 2003 NRS. What size should I order, the 30.8 or the 30.9? and what length? (Im 5'8 and like my seat reasonably high.)
    thanks
    g
    "Drinking and driving is wrong, but hey, the kids gotta get to school right?"
    -Dave Attell

  2. #2
    hooked on quack
    Reputation: Duckman's Avatar
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    30.8x410mm.

    A 30.9 "will" work tho.

    See this for the reason why the length...

    enjoy


    http://forums.mtbr.com/showthread.ph...64560#poststop

  3. #3
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
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    Just to add to what Duck sez, my RF XY 30.9 fit my NRS like a glove, but Giant warranty warned me that I must maintain at least 6"/150mm insertion if I'm doing away with the shim. With the relatively thin Allux tubing and low TT junction, it's best not to take any chances and purchase the longest post you can find.

  4. #4
    NRS
    Reputation: nygeo's Avatar
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    Ok...I am not sure exactly what to do here. If a 30.9 "will" fit...then isnt that the appropriate size? Im inclined to get the 30.9 because it may be a snugger and safer fit. What reason would there be for getting the 30.8?
    g
    "Drinking and driving is wrong, but hey, the kids gotta get to school right?"
    -Dave Attell

  5. #5
    hooked on quack
    Reputation: Duckman's Avatar
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    Non really. Thats why most mfgs just make a 30.9. This whole 30.8/30.9 thing makes me tired as well. Its considered the correct size FWIW. The snug'r fit "might" scratch up a carbon post sooner...but thats the only thing I can think of, short of making it more tempting to grab the seat and twist upward when removing it or adjusting it higher..instead of grab'n the post for that action. This might damage a pressed on head type post like a Syncros or equal.

  6. #6
    TEAM TOPEAK - ERGON
    Reputation: KERKOVEJ's Avatar
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    Get the 27.2

    Stay with the Manf. spec.!!!! Get the 27.2 and use the shim. For length, run the "trusted" 350mm for tons of adjustment. I believe there might be warranty issues if you don't use the shim.

    Just my 2 cents worth

  7. #7
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
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    Quote Originally Posted by KERKOVEJ
    Stay with the Manf. spec.!!!! Get the 27.2 and use the shim. For length, run the "trusted" 350mm for tons of adjustment. I believe there might be warranty issues if you don't use the shim.

    Just my 2 cents worth
    As I stated, "spec" in this case (according to Giant warranty dept.) allows for the no shim option: The "official" choices are (a) 27.2 + shim + 100mm of insertion or (b) 30.8 + at least 150mm insertion. Saying "350mm for tons of adjustment" just doesn't cut it. I was running a 410mm post and barely made the 150mm requirement.

    As for 30.8 versus 30.9, I can only tell you that I was nervous about it, but the 30.9mm Rac Face XY fit *perfectly*, as if it were made for that frame. No twisting, forcing, shoving, etc. It glided in and glided out. Everyone on these boards who have tried it -- and there have been many -- report similar experiences, even with other brands of seat posts. Yes, it's possible the user is taking a chance that the post won't fit and they'll have to return it, but so far I haven't heard of anyone having that trouble. And yes, a little common sense is required on the part of the owner, knowing that the potential for a mis-fit is there.

  8. #8
    hooked on quack
    Reputation: Duckman's Avatar
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    100% WRONG. Thats a silly statement. The 30.9x410mm IS in factory specs. Also...a 410mm offers TONS more adjustability then any 350mm, unless this is some kinda new math your using. The 30.9 post on my epic NRS IS stronger at this junction then my NRS race bikes wonderful(relatively flimsy and heavy as hell)factory shim with an USE carbon 27.2 post...thats a fact since the longer post goes all the way down to the levell of the upper shock pivot.

  9. #9
    NRS
    Reputation: nygeo's Avatar
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    Well...just got

    my 30.9 Thomson seatpost in the mail. It's so funny cause now I know what is meant by "It "fits""...Indeed it does "fit" but its a tight squeeze! I greased up the post and tube and it went in with a little effort (twisting) but its IN. And it looks great and FEELS great and I think its worth the effort cause the fit is just tight and you could tell that its NEVER going to squeak. Id be more confident on this set up than a straight TUBE running from the bb to my seat.
    thanks for the insight,
    g
    "Drinking and driving is wrong, but hey, the kids gotta get to school right?"
    -Dave Attell

  10. #10
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    NRS Seatpost

    I just put a 30.9 Easton Carbon seatpost on my 2003 NRS Air and it fit fine. The shim on the old seatpost was a 30.8. I don't think that the .1 in size makes a difference.

  11. #11
    On MTBR hiatus :(
    Reputation: Speedub.Nate's Avatar
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    Quote Originally Posted by jenlee
    I just put a 30.9 Easton Carbon seatpost on my 2003 NRS Air and it fit fine. The shim on the old seatpost was a 30.8. I don't think that the .1 in size makes a difference.
    I wouldn't want to create the impression that .1mm doesn't make a difference in all cases. I've tried .2mm differences and it's a killer -- something you don't want to do intentionally because you'll find yourself literally *screwing* the post into the frame. With the Giants, 30.9 happens to work out in most cases, buy nygeo's report that his took a little bit of "twisting" made me cringe. With my XY, when I purchased it nearly 3 years ago, I asked Speedgoat to mic the post they were sending me because I didn't want any problems, and as I indicated, it fit flawlessly. But with Thomson and their flavor ridges left over from the machining process, you'd have to expect there might be a "catch".

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