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  1. #1
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    c.1992 Diamondback Apex LE stem replacement?

    Hi All,

    I'd like to replace the stem on my c.1992 Apex LE (I got it in 1992 used, but I think it is a 1989 model) with the "original" stem.

    Question: How do I go about this to make sure that the part I am considering will fit my bike?


    The 1989 Diamondback catalog:
    Pages 6 & 7 | 1989 Diamond Back Catalogue | Retrobike


    The new stem I am considering:
    Tioga Avenger Tbone Stem 25 4" | eBay



    THANKS in advance for any advice.
    --eric

    My c.1992 Diamondback Apex LE:
    Attached Thumbnails Attached Thumbnails c.1992 Diamondback Apex LE stem replacement?-after2.jpg  


  2. #2
    Sneaker man
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    That is later than an 89, more likely a 91 (by decals,the 89's had little semafore flags in the branding). So you really need to check that it isn't an oversized headset (probably not, I think they still ran the same frame from 89 till 91/92, but I think the axis was oversizes by then, so Apex could be too...or not). But yeah a Tioga t-bone would fit the bill (I lost mine somewhere along the way)
    All the gear and no idea.

  3. #3
    Sneaker man
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    oohps I see the one you linked IS oversized, so yeah just better check that it is or isn't oversized. (1in vs 1-1/8 or was oversided back then 1-1/4 or was it already called evolution by then??)

    But also, what is wrong with the stem on there?
    All the gear and no idea.

  4. #4
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    Thanks for the reply. I wanted to experiment on using a shorter stem maybe a 105mm. The current one is about 130mm. I used to have a 17" 1989 Diamondback Sorrento (entry level), and I remember it was much more maneuverable (turning into the corners) than my 18" c.1992 Apex LE. But then maybe it is me getting old.

    Question: How exactly should I measure the headset or headtube diameter? Is it just the outer diameter, or do I need to find out the inner diameter? I do have a caliper. Thanks in advance.

  5. #5
    Sneaker man
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    stem might have it written (probably not), you need to measure the diameter where it enters the headset, or if you take it out the internal diameter of headset. it'll be 1 inch [standard at the time] , 1-1/8 [oversize] or 1-1/4 [evolution]. haha I've never ever converted inch to mm in headset sizes, so whatever they are i corresponding metric sizes apart form the decimal of imperial (1, 1.125, 1.25).

    edit;
    ...so the linked stem is OverSize, but 25.4mm with is 1 inch... I always thought they were the newer sizes...so maybe it refers to something different...or maybe I don't know what O.S. is...
    All the gear and no idea.

  6. #6
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    Thanks for the reply. I'll have to figure out how to measure the inner diameter then.

    Question: How about threaded vs non-threaded? Is that something I should be concerned about when it comes to getting a new stem for an old bike? How would I determined that as well?

  7. #7
    Sneaker man
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    yeah, loos like you have threaded (so far as I can see). the difference is that threaded, the fork pokes up a above the frame a little bit, same height as the headset. It has threads on it, the headset op then screws onto it, then a lock nut screws on top of that. Then the stem goes inside all that, iside the steerer tube and is lock in by an expanding quill arrangement. Unusually spotted by there being just on bolt to do up on the top of the stem and the headset has two big...er...things that look like you would do up with a very large adjustable spanner.
    Aheadset style the fork pokes up a lot above the frame, the headset assemble slides over it and down to the frame, while there is still a lot of fork steerer tube above that. The stem then also slides on, then does up with bolts on the side of the stem.It also has a cap on top which is used to compress everything (as opposed to the screw in onto the fork in the threaded version). You can tell as there is no screwing ... er... bits on the headset, the stem has bolts to tighten it ROUND the stem rather than into it, and there is a metal(or plastic) topcap that screws down (that looks like it might be a quill style) but you can take it off and look down into the fork and see the star nut (that it screws into)


    stolen from parktools site: to get the idea, things may vary abit dependingon model

    threaded



    threadless

    All the gear and no idea.

  8. #8
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    To clarify the 25.4 being over sized, that would fit the 1-1/8" fork. You're looking at the inner diameter of the steerer tube. Since steel fork steerer tubes use 1/16" thick steel, you subtract 1/8" to get the inner diameter. A 1" fork uses a 7/8" quill mast, a 1-1/8" fork uses 1" and 1-1/4" forks use a 1-1/8".

  9. #9
    Sneaker man
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    Yeah, yeah...all ^ that! (never actually knew all that...never had to I guess)
    All the gear and no idea.

  10. #10
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    Thanks for the replies, much appreciated.

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