Thomson stem issues

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  • Thomson stem issues
  • rabriguez
    Member

    I have recently added a Thomson stem to my camber 29er and have noticed a lot of play in the headset. I changed back to the stock stem (specialized own branded) and the play disappears. On investigating the specialized stem there is a small shim marked 8. 16. This appears to have a slight bevel to it

    Has anyone had similar issues or know of a solution to my woes?

    Thanks in advance

    _tom_
    Member

    It’s probably a lower stack height so when you’re tightening up the top cap it’s just bottoming out on the steerer and not actually loading the bearings. You’ll need to either trim the steerer a bit or add a spacer above or below the stem.

    rabriguez
    Member

    Thanks Tom. It all seems to fit pretty well but there is the slightest of gaps with the Thomson that the stock stem doesn’t have. It’s had me frustrated all night!

    robarnold
    Member

    The stock stem has an insert that allows you to change the angle of rise/fall, that is what the 8/16 refers to. I think you’ll find that it’s prefixed by a + or -. The gap in the insert must line up with the gap in the stem. The stem comes with an eccentric top cap which you shouldn’t use with a standard stem as the hole for the bolt isn’t centred.

    As Tom says, all this probably has nothing to do with your headset, you’ll be bottoming out your top cap on your steerer. If any part of the underside of the top cap is touching the fork steerer the whole lot won’t preload the bearings. You need a good 3-4mm gap between the top of the steerer and the top of the stem before you start tightening up the top cap. Put a slim spacer between stem and top cap and you’ll be laughing

    rabriguez
    Member

    Robarnold

    Thanks for the informative response. I have 2 spacers under the stem, one on top of the stem then the stem cap itself. If using the Thomson stem I think your implying purchasing a different stem cap, would that be correct?

    STATO
    Member

    Apparently the speccy top cap is offset and needs replaced if you change stem, tho as its only preloading the headset its not that important once the stem is done up.

    What he is saying tho, before you fit the top cap you should check the top spacer should sit above the top of the steerer by a few mm, this is to ensure when you tighten the top cap there is space to take up the slack. No space here = slack in headset = rattle.

    Therefore, you may need to add another spacer?

    titusrider
    Member

    What everyone is trying to say is it should look like this only less so
    http://singletrackworld.com/forum/topic/is-this-safe-2

    robarnold
    Member

    Rabriquez, STATO, that’s exactly what I was saying. Different top cap required and make sure there is room for slack to be taken up before you start tightening everything up

Viewing 8 posts - 1 through 8 (of 8 total)

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