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  1. #1
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    Admit it here...who's shimming?

    Need a new post for my HT and I had been shimming my 27.2 to a 31.6. I figured it was cheaper and more comfortable. Who's doing it? I'll probably go c. fiber for the post again....
    thanks!

  2. #2
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    I've been running a Niner EMD with Race Face Next 27.2 carbon post shimmed out to 31.6 for a while now, with no issues. I think I can feel a little more compliance from the post compared to my old Air 9 frame with an unshimmed 31.6 Thomson, but the effect is less than a few PSI of air pressure in the tires.

  3. #3
    Airborne Product Dude
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    Quote Originally Posted by toddre View Post
    Need a new post for my HT and I had been shimming my 27.2 to a 31.6. I figured it was cheaper and more comfortable. Who's doing it? I'll probably go c. fiber for the post again....
    thanks!
    I'm not a big fan of shims unless they are long enough to pass below the tube juncture on the frame. Most commercially available shims don't take every frame design into account and put more stress than intended on the frame. Will it break? Probably not.......but why take that chance?
    Airborne Dude.

  4. #4
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    I admit...

    I was, for a while.
    But not for the reasons you had in mind...


    Don't know what happend at Thomson, but someone must 've been sleeping.
    All sorted out now, a brand new Thomson is smiling at me, from my desk.
    Belgian beer and Scotch whisky.

  5. #5
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    Shimmed 27.2 in a 31.6 slot on my Access 29er frame.

    I'd picked up a straight 31.6 post when I built it but it wasnt comfortable so I pulled out an old setback 27.2 post and picked a shim up from the LBS and was good to go. Only gripe is messing with the shim if I slam the post for more aggressive descending.

  6. #6
    Big Boy
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    Funny, I thought I clicked on the "29er bike" forum.
    -It's time to shred some mild to moderate gnar!!

  7. #7
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    Quote Originally Posted by texasnavy05 View Post
    Funny, I thought I clicked on the "29er bike" forum.
    One of those, huh?

  8. #8
    AZ
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    Quote Originally Posted by texasnavy05 View Post
    Funny, I thought I clicked on the "29er bike" forum.




    No mistake. I use a 29er specific shim. Don't want to see a perfectly good carpet fibre seat post sit in a parts box.

  9. #9
    Big Boy
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    Quote Originally Posted by toddre View Post
    One of those, huh?
    "those" being people who think you should post a thread in the correct sub-forum.

    Yes. I am one of "those".
    -It's time to shred some mild to moderate gnar!!

  10. #10
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by toddre View Post
    Need a new post for my HT and I had been shimming my 27.2 to a 31.6. I figured it was cheaper and more comfortable. Who's doing it? I'll probably go c. fiber for the post again....
    thanks!
    I shim my dropper post. Bought a 27.2 so I can use it with several different frames I have.

    Use the proper diameter for regular posts. My 31.6 posts did not cost me more than $35 each. A couple were $9, less than the shims I have for the dropper.
    mtbtires.com
    The trouble with common sense is it is no longer common

  11. #11
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    Quote Originally Posted by texasnavy05 View Post
    "those" being people who think you should post a thread in the correct sub-forum.

    Yes. I am one of "those".
    Yah! I mean c'mon, the "29er components" forum is just one line lower than this one!
    "That's a niiiiiiiice biiike boy! That a Huffy!?"

  12. #12
    FM
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    I've seen numerous frames screwed up from running shims and under-size dropper posts. Both aluminum and steel. Something I am looking into repairing on my steel hardtail right now. No fun

  13. #13
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    Some Giant frames in the past came with a seatpost shim as standard. They required a longer insertion length if a seatpost without a shim was used.

    Tim

  14. #14
    usually cranky
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    Quote Originally Posted by thasingletrackmastah View Post
    I was, for a while.
    But not for the reasons you had in mind...


    Don't know what happend at Thomson, but someone must 've been sleeping.
    All sorted out now, a brand new Thomson is smiling at me, from my desk.
    was that on a 29er? you're asking for trouble man, thats a dh/fr shim.

  15. #15
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    Quote Originally Posted by FM View Post
    I've seen numerous frames screwed up from running shims and under-size dropper posts. Both aluminum and steel. Something I am looking into repairing on my steel hardtail right now. No fun
    Really?

    I ran a shim on my old aluminum hard tail (31.6) with a 27.2 GD for the last few years, just switched to a Yelli, also shimmed, with the same 27.2 dropper post.

    What's the screw up? From the shim being too short?

  16. #16
    FM
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    Quote Originally Posted by grundy View Post
    Really?

    I ran a shim on my old aluminum hard tail (31.6) with a 27.2 GD for the last few years, just switched to a Yelli, also shimmed, with the same 27.2 dropper post.

    What's the screw up? From the shim being too short?
    Not really sure. My guess is that "under tolerances" stacked up and caused the frame to deform. Or, maybe the shims were too short, creating too much leverage on the top of the seat tube, creating bending or deformation.

    Bike #1 is my curtlo hardtail, 28.6 seat tube with a shim, 27.2 GD classic.
    Bike #2 was a friends diamonback mission, I think those are 30.9, he was also running a shim down for a gravity dropper.

    On both bikes, the effect is the seat tube is crimped or deformed so changing seat height or removing the post involves 10-15 minutes of bike wrestling.

    Gonna take my curtlo into a local frame shop to look into repair, hopefully it's an easy fix (and with steel, good chance it might be)

  17. #17
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    Well good time to discuss the nicer (longer) shims from the cheaper (shorter) shims?

    I think I've got a Cane Creek in my frame and IIRC it was around 3" long, long enough to get through the top tube/seat tube junction on my frame.

  18. #18
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    Quote Originally Posted by thasingletrackmastah View Post
    Don't know what happend at Thomson, but someone must 've been sleeping.
    All sorted out now, a brand new Thomson is smiling at me, from my desk.
    Thomson seatposts often run undersized. Thomson did exchange a couple of undersized Elites for me, but I've sort of given up on Thomson and gone to Ritchey.

  19. #19
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    Quote Originally Posted by b-kul View Post
    was that on a 29er? you're asking for trouble man, thats a dh/fr shim.

    Seriously, 29er shims should only be made out of beer cans and preferably a good quality micro brew.

  20. #20
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    Quote Originally Posted by toddre View Post
    Need a new post for my HT and I had been shimming my 27.2 to a 31.6. I figured it was cheaper and more comfortable. Who's doing it? I'll probably go c. fiber for the post again....
    thanks!
    I've been running shims on my dropper post for the nearly 7 years I've owned it on 4 different frames. No issues.
    15mm is a second-best solution to a problem that was already solved.

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