Why are the headset spacers "required" on purchasing a new bike?- Mtbr.com
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  1. #1
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    Why are the headset spacers "required" on purchasing a new bike?

    Overheard this at my LBS...

    Why are the headset/stem spacers "required" for the purchase of a new bike?

    I believe there is a required height for all/many manufacturers, from what I understood anyway.

    My 09 Stumpjumper has three 10mm spacers.

    Just curious if there is a reason (similar to the reflector requirement, etc)

  2. #2
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    Adjustability.

    They install them because there is no way for the manufacturer to know how high to place the bars for everyone.

    If they didn't put them on, there would be no way to raise the bars without a new stem.

    You can always lower the bars, but you can't raise them once the steer tube is cut too short.

  3. #3
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    Ah, gotcha.

    Thanks for the response.

    I wasn't sure if there was some other BS law/rule that requires them to be at a certain height for "riders to maintain maximum visibility of the road".

    This makes logical sense.

  4. #4
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    You want at least a small spacer above the stem so that there is contact with the fork along the entire width of the stem.

  5. #5
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    At least some fork manufacturers specify 30 mm of spacers as the maximum recommended height. I expect it is CYA, much like "lawyer lips" on the dropouts.

    -mud
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  6. #6
    Hairshirt Rider
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    Quote Originally Posted by flargle
    You want at least a small spacer above the stem so that there is contact with the fork along the entire width of the stem.
    oh really?

  7. #7
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    Quote Originally Posted by Loudpawlz
    oh really?
    Well, I do. You might not.

  8. #8
    San Diego County
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    Quote Originally Posted by flargle
    Well, I do. You might not.
    I do not. The stem should sit flat just fine by itself against the top of the headset or the top cap.
    Last edited by Duzitall; 09-08-2009 at 04:16 PM.
    Quote Originally Posted by turnerbikes View Post
    Of course the easiest way to fix this is to go for a hike.
    DT

  9. #9
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    Quote Originally Posted by flargle
    You want at least a small spacer above the stem so that there is contact with the fork along the entire width of the stem.
    Some forks with carbon steerer tubes recommend doing this so that the top of the steerer tube does not get crushed.

    I usually do it so that the stem has full contact with the steerer tube. Also, it allows a little adjustment later on and enough steerer tube if the stem is replaced with one that has a longer clamp.

  10. #10
    Harmonius Wrench
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    Quote Originally Posted by Polk
    Some forks with carbon steerer tubes recommend doing this so that the top of the steerer tube does not get crushed.

    I usually do it so that the stem has full contact with the steerer tube. Also, it allows a little adjustment later on and enough steerer tube if the stem is replaced with one that has a longer clamp.
    Or if you replace your headset and it has a taller stack height.

    Better to have some "wiggle room", than be caught out by a variance in parts.
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  11. #11
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    Quote Originally Posted by Polk
    Some forks with carbon steerer tubes recommend doing this so that the top of the steerer tube does not get crushed.
    2-3mm is factory recommended for my Reynolds Ouzo Pro fork w/ carbon steerer on my roadie.
    Happiness depends more on the inward disposition of mind than on outward circumstances. Benjamin Franklin

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