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  1. #1
    is slower than you Peek the Geek's Avatar
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    Lip on shim for stem....top or bottom?

    Okay, I'm gonna try my best to describe this. I apologize if this gets confusing.

    I had a bike fitting done today at a Minnesota bike shop. Among other things, it was decided I would need a shorter stem, so the shop guy takes the old one off and starts to put the new one on. An important detail here is that I have a 1" steerer tube and 1" headset, and the stems are Ritchey WCS 1 1/8" inch stems that come with shims for using the stems on 1" steerers. Like other shims I've seen, these have a lip around the perimeter of one end.

    So, the shop guy proceeds to install the stem with the lip of the shim underneath the stem. Then he says, "You can't use the top cap you're using with this because the top cap is 1" and only presses down on the shim---not the stem itself." (Can you picture what I'm describing?) "You need to use a 1 1/8" top cap."

    So I say, it's my understanding that the lip of the shim goes above the stem, so that the top cap presses down on the shim, which in turn presses down on the stem.

    Shop Guy: "No, the lip goes underneath."

    Me: "But I had it the other way, and it worked fine."

    Shop Guy: "No you didn't. The lip was on this side of the stem when you brought it in."

    Me: "Yes, but you flipped the stem to an upward angle. It was angled downward when I came in."

    Shop Guy: "No it wasn't."

    Me: "Yes it was."

    Shop Guy: "No it wasn't."

    Me: "Okay, fine. Put it on your way with a 1 1/8" top cap. Just make sure I get my 1" to take with me."

    So.... How should the shim be installed? With the lip on top and the 1" top cap that came with the headset? Or with the lip on the bottom and a 1 1/8" top cap he had laying around? (And if the lip goes on the bottom, why the hell is it there in the first place?)

    Thanks for reading.
    Last edited by Peek the Geek; 04-28-06 at 09:04 AM.
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  2. #2
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    Basically the top cap sets the preload on the bearings. As long as it's pressing down on something solid (without the stem bolts tightened) you're good. If you can get decent pre-load in your configuration, you're fine. The top cap doesn't keep anything together really, in fact, you can take it off (with the stem tightened, that is) and nothing would happen. It simply sets the preload between the fork and the lower race until you tighten the stem bolts down.

  3. #3
    Senior Member Old_Fart's Avatar
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    I have used several Ritchey stems and I put the shim with the lip under. I reasoned it thusly;
    If you have to have the lip there, put it on the bottom where it is slightly less visible.
    If you use a 1-1/8" cap directly against the stem it once again has a cleaner look than a 1" cap with the shim poking out.
    Functionally, the lip/shoulder of the shim, when on the bottom, helps the stem sit firmly against the smaller ID spacers and/or headset pieces. Since the stem typically sticks above the stearer tube by a mm or three. having the shim up there does nothing. Since the the clamping force against the stearer goes all the way to the bottom of the stem, it does more good there.
    Also, if the lip is down, the shim stays in place better as you push the stem/shim combo down on the stearer. With the lip up, it can slide out as you push the pieces down.


    All in all, I'm sure it would work fine both ways, all of my reasons are trivial. I still will always put the lip down.

  4. #4
    is slower than you Peek the Geek's Avatar
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    Quote Originally Posted by ivan_yulaev
    Basically the top cap sets the preload on the bearings. As long as it's pressing down on something solid (without the stem bolts tightened) you're good. If you can get decent pre-load in your configuration, you're fine. The top cap doesn't keep anything together really, in fact, you can take it off (with the stem tightened, that is) and nothing would happen. It simply sets the preload between the fork and the lower race until you tighten the stem bolts down.
    Yep, I know what the top cap is for and how to install and adjust headsets. The fact that everything will function fine either way is the reason I just agreed and let him do what he wanted. I'm just not so sure that the shim was meant to be installed that way and that I can't use my 1" top cap. I tried finding specifics on Ritchey's site, but no luck.
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  5. #5
    is slower than you Peek the Geek's Avatar
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    Quote Originally Posted by Old_Fart
    I have used several Ritchey stems and I put the shim with the lip under. I reasoned it thusly;
    If you have to have the lip there, put it on the bottom where it is slightly less visible.
    If you use a 1-1/8" cap directly against the stem it once again has a cleaner look than a 1" cap with the shim poking out.
    Functionally, the lip/shoulder of the shim, when on the bottom, helps the stem sit firmly against the smaller ID spacers and/or headset pieces. Since the stem typically sticks above the stearer tube by a mm or three. having the shim up there does nothing. Since the the clamping force against the stearer goes all the way to the bottom of the stem, it does more good there.
    Also, if the lip is down, the shim stays in place better as you push the stem/shim combo down on the stearer. With the lip up, it can slide out as you push the pieces down.


    All in all, I'm sure it would work fine both ways, all of my reasons are trivial. I still will always put the lip down.
    Makes sense. So do you just not use the top caps that are supplied with your 1" headsets?
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  6. #6
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    Here's what I'm thinking:

    If the stem is a bit longer than the shim, then use the 1 1/8" cap and put the lip on the bottom. The cap will press against the top of the stem, and the bottom of the stem will press against the lip. The shim will then press against the lower spacers. I believe that is the intended design.

    If the shim is longer than the stem, then you'll likely want to use the 1" cap and let it press against the shim.

    Is the shim the same length as the stem? In that case, I honestly don't know which top cap to use, but I"d still probably go with the 1 1/8". Or I'd cut the shim down so that it's +/-3mm shorter than the stem.

    I think the ideal situation is for the cap to press against the stem, and the stem to press against the lower lip of the the shim. In all situations, I'd put the lip on the bottom.

    Hope that helps.

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    Ha ha ha, I laughed out loud at the "no it wasn't" "yes it was" part of your story. I've had many similar conversations at bike shops about all sorts of things, including the correct pronunciation of "Bianchi".

    The shims I have used have no lip at all, so... well, I just don't know.

  8. #8
    hello roadfix's Avatar
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    The bottom line is either way works......
    .cinelli.olympic.surly.long.haul.trucker.kona.ku.surly.steamroller.
    .litespeed.classic.litespeed.firenze.bianchi.pista.dean.colonel.plus.more.

  9. #9
    is slower than you Peek the Geek's Avatar
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    Quote Originally Posted by The Fixer
    The bottom line is either way works......
    That's certainly how it appears. I actually sent an e-mail to Ritchey, asking them if either way is preferred. I've tried e-mailing them with a technical question before, though, and never received a response, so I'm not holding my breath.

    Thanks for the input, everyone.
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  10. #10
    is slower than you Peek the Geek's Avatar
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    Okay, here's an update. I got a response from Ritchey (very quickly, I might add), and it looks like everybody's right. Here's their response:

    "Either or, if you put the lip on top you can use a 1" top cap.
    If you put the lip on the bottom you should use a 1-1/8" top cap.

    GO PACKERS!
    Ritchey Info"


    Aesthetically, I think the lip looks better up top. And I don't have to use the f'ugly 1 1/8" cap the shop gave me.
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  11. #11
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    Sweet. Now we've all learned something today.

    I also laughed out loud at the "yes it was" "no it wasn't" thing. I was ready for somebody to yell "Hey Moe" and poke someone in the eye.

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