Question about seatposts and shims

Discussion in 'Mountain Bikes' started by Northern Pie, Apr 6, 2003.

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  1. Northern Pie

    Northern Pie Guest

    Question about seatposts and shims

    Ebikes go fast which means shock-absorbing seatposts and *soft* saddles (e.g. Velo/CCM Mega Gel) are
    imho mandatory.

    Questions:

    1) Is is possible to machine down a shock seatpost from 27.2mm to
    2.4mm without compromising safety?

    3) Is it true that a shim made from pop can aluminum will be good enough to shim a post from 27.2mm
    to 28.6mm?

    Thanks for all replies!
     
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  2. Sorni

    Sorni Guest

    "Northern Pie" <[email protected]> wrote in message
    news:[email protected]...
    > Question about seatposts and shims
    >
    > Ebikes go fast which means shock-absorbing seatposts and *soft* saddles (e.g. Velo/CCM Mega Gel)
    > are imho mandatory.

    Bzzt. Wrong. (Whatever an "ebike" is.)

    > Questions:
    >
    > 1) Is is possible to machine down a shock seatpost from 27.2mm to
    > 25.4mm without compromising safety?

    No.

    > 2) Is it true that a shim made from pop can aluminum will be good enough to shim a post from
    > 27.2mm to 28.6mm?

    Better use a beer can. The injuries won't hurt as much.

    > Thanks for all replies!

    NP.

    Bill "southern pudding" S.
     
  3. Andy Chequer

    Andy Chequer Guest

    "Northern Pie" <[email protected]> wrote in message
    news:[email protected]...
    > Question about seatposts and shims
    >
    > Ebikes go fast which means shock-absorbing seatposts and *soft* saddles (e.g. Velo/CCM Mega Gel)
    > are imho mandatory.
    >
    > Questions:
    >
    > 1) Is is possible to machine down a shock seatpost from 27.2mm to
    > 25.4mm without compromising safety?

    I really wouldn't.

    > 2) Is it true that a shim made from pop can aluminum will be good enough to shim a post from
    > 27.2mm to 28.6mm?

    No. IME, the beer can shim will work for a seatpost only if there is one layer of the can material..
    If you wrap it round several times, it will slide over itself and the seatpost will slip.

    Either get the right size post or buy a post with a purpose built shim.

    Andy Chequer
     
  4. Nelson Binch

    Nelson Binch Guest

    "Andy Chequer" <[email protected](youdontwantthisbitinit)thisisasparagus.com> wrote in message
    news:[email protected]...
    |
    | "Northern Pie" <[email protected]> wrote in message
    | news:[email protected]...
    | > Question about seatposts and shims
    | >
    | > Ebikes go fast which means shock-absorbing seatposts and *soft* saddles (e.g. Velo/CCM Mega Gel)
    | > are imho mandatory.
    | >
    | > Questions:
    | >
    | > 1) Is is possible to machine down a shock seatpost from 27.2mm to
    | > 25.4mm without compromising safety?
    |
    | I really wouldn't.
    |
    | > 2) Is it true that a shim made from pop can aluminum will be good enough to shim a post from
    | > 27.2mm to 28.6mm?
    |
    | No. IME, the beer can shim will work for a seatpost only if there is one layer of the can
    | material.. If you wrap it round several times, it will slide over itself and the seatpost
    | will slip.
    |
    | Either get the right size post or buy a post with a purpose built shim.

    If you are in the US, see your LBS and ask them to order a shim from QBP called "Problem Solvers"
    (there are many other manufacturers BTW) Just go to them, tell them your inside and outside
    diameters and there you go.

    ---
    __o _`\(,_ Cycling is life, (_)/ (_) all the rest, just details. Nelson Binch =^o.o^=
    http://intergalax.com

    Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.467 / Virus Database: 266 -
    Release Date: 4/1/2003
     
  5. Northern Pie wrote:

    > 2) Is it true that a shim made from pop can aluminum will be good enough to shim a post from
    > 27.2mm to 28.6mm?

    aluminum cans are quite surprisingly accurate in thier uniformity of thickness
     
  6. Northern Pie wrote:

    > Question about seatposts and shims
    >
    > Ebikes go fast which means shock-absorbing seatposts and *soft* saddles (e.g. Velo/CCM Mega Gel)
    > are imho mandatory.
    >
    > Questions:
    >
    > 1) Is is possible to machine down a shock seatpost from 27.2mm to
    > 25.4mm without compromising safety?
    >
    > 2) Is it true that a shim made from pop can aluminum will be good enough to shim a post from
    > 27.2mm to 28.6mm?
    >
    > Thanks for all replies!

    1: NO!
    2: it would be better to stop by your LBS and get a shim that is made for the purpose.

    Most of the shockabsobing posts you'll be looking at come in 1 or 2 sizes, they most likely come
    with the shims you'll need.
     
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