Adaptor to use smaller seat post on larger frame?- Mtbr.com
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  1. #1
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    Adaptor to use smaller seat post on larger frame?

    I have a 27.2 bike and a 30.9 bike....in my fantasy world I could buy a 27.2 adjustable seatpost (Kindshock I7) then adapt it up so the 30.9 could use it as well.

    Does anyone offer such a mystical device (bushing) and if so does it actually work?

  2. #2
    meow meow
    Reputation: b-kul's Avatar
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    ive heard shimming an adjustable seatpost is less than desirable.

  3. #3
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  4. #4
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    Quote Originally Posted by b-kul
    ive heard shimming an adjustable seatpost is less than desirable.
    I've been running a 27.2 Gravity Dropper in a 30.9 Heckler for two years with no problems.

  5. #5
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    Quote Originally Posted by Glenn D.
    I've been running a 27.2 Gravity Dropper in a 30.9 Heckler for two years with no problems.
    How much do you weigh? Usually the force of the post bottoming out when you drop it exacerbates the problem of using a shim. I've had bad luck recently with using a shim on even a regular seatpost. My post would keep slipping throughout the ride until it was much lower than desired. Shimming can really be hit or miss. I would think it would be even more likely to slip on a drop post due to the issue I mentioned. The lighter you weigh the less likely you are to have an issue. They do make them though and they're cheap so it doesn't cost much to try.
    Gotta get up to get down.
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  6. #6
    meow meow
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    Quote Originally Posted by BaeckerX1
    How much do you weigh? Usually the force of the post bottoming out when you drop it exacerbates the problem of using a shim. I've had bad luck recently with using a shim on even a regular seatpost. My post would keep slipping throughout the ride until it was much lower than desired. Shimming can really be hit or miss. I would think it would be even more likely to slip on a drop post due to the issue I mentioned. The lighter you weigh the less likely you are to have an issue. They do make them though and they're cheap so it doesn't cost much to try.
    thats what i was thinking. also compounded by the fact that adjustable posts (at least my reverb) are so picky to clamping force. too much and it wont move, too little and the post will just fall down.

  7. #7
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    Quote Originally Posted by BaeckerX1
    My post would keep slipping throughout the ride until it was much lower than desired.
    Have you tried using Carbon Grip? It works on more than carbon.

    More importantly, you using a plastic or an alu shim? IME Alu ones are much less likely to slip, but need plenty of grease/anti sieze on them before they go in the frame.

  8. #8
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    Quote Originally Posted by Fix the Spade
    Have you tried using Carbon Grip? It works on more than carbon.

    More importantly, you using a plastic or an alu shim? IME Alu ones are much less likely to slip, but need plenty of grease/anti sieze on them before they go in the frame.
    It was an aluminum shim. I got a new post so it's not an issue. I know about the carbon paste. They specifically mention using it in the Reverb manual instead of grease. I'm going to get some to help my Reverb slipping issues, but haven't gotten around to it yet.
    Gotta get up to get down.
    LMB

  9. #9
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    It depends on what kind of bike you have. You'd need shim, best place to get is Gravity dropper website, they have just about every popular size and the cup is deep enough. Some companies don't recommend using the shim because the cup may not be long enough and the post can potentially damage the seat tube.

    I've been using the 27.2" gravity dropper and AMP post on my 28.6, 30.9, and 31.6 bike for a few years and have no problem with the issue at all. Clamping force should not be a big factor on the i7r. It's more of an issue for mechanical posts than hydro from my experience, not including Reverb.

    I usually use ti prep or carbon prep to help reduce the clamping force, and prevent bond.

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