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  1. #1
    Mr. Knowitall
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    New question here. Project 321, CK headset and stack height

    I had a theoretical 1.5mm to go on stack height om my headset/headtube stack on my bike to fit between XL clamps on the Lefty. Now that I have installed it, the upper adaptor is 1-2mm from having full contact with the inner clamp surface.

    My points here are:
    - Is this ok?
    - CK and stack height cannot be trusted
    - Do I need to go for a lower stack headset like CB Opium or similar?

    I am going to a bike gathering soon, so I will need to fix this ASAP.

    Help and input is much appreciated

  2. #2
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    I had the same case when installed Lefty Max (regular, not XL) on my Mojo L, upper Project321 adapter was 2mm over the upper Lefty's clamp. I just left it this way, there are still 8-9mm clamping surface, no problem so far since then.

  3. #3
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    picture?

  4. #4
    Mr. Knowitall
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    It was very difficult to capture the gap on film, unfortunately. The insert is extending a ~5mm above the clamp, and the top cap of the headset intruding a bit into the clamp "area" by one mm or thereabouts.

  5. #5
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    A little bit crappy pictures......Project 321, CK headset and stack height-2010-06-017.jpg

    Project 321, CK headset and stack height-2010-06-020.jpg

  6. #6
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    Forgot to mention.... inside HT is Cane Creek IS3 headset.

  7. #7
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    This is fine guys. The top ring of our adapter is machined 2.5mm thicker than the top
    crown for this very reason. If you only have 2mm above the crown your very close to flush
    on bottom. DO NOT let the top ring extend more than 3mm in either direction (up or down) from the top crown. At that point you would begin to loose contact area and clamping force on the steerer tube.

    As always feel free to call our toll free number if you have any questions regarding our products.
    Jake
    Project321
    877-584-7321
    http://www.project321.com/

  8. #8
    I want to ride
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    I don't understand... I have a lefty fork, the clamps are bonded on the lefty "shaft". with all the different headtube sizes out there How can I ever possibly get a tight fit. I'm confused.

  9. #9
    Mr. Knowitall
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    Quote Originally Posted by pumpkinbiter
    This is fine guys. The top ring of our adapter is machined 2.5mm thicker than the top
    crown for this very reason. If you only have 2mm above the crown your very close to flush
    on bottom. DO NOT let the top ring extend more than 3mm in either direction (up or down) from the top crown. At that point you would begin to loose contact area and clamping force on the steerer tube.

    As always feel free to call our toll free number if you have any questions regarding our products.
    Thanks Jake. My problem was the opposite - I have lost some clamp area by 1.5mm. My calculations were that the total stack height should be 161.5mm, but actual proved to be ~164.5-165mm. I got the fork to fit, but the insert is only extending above and is not flush below. Seems it is a bit difficult to describe this in writing without any pictures (tried as mentioned above).

    I am going to a bike gathering for 4 days, and have started my desperate search for a new headset that is good but not too expensive and lower than CK. A bit stressed out now

    Will it hurt to have ~1.5mm lost clamping height for one ride or two?

    I am in Norway, so your toll free number won't be that toll free for me, though. But it is a good service for your countrymen

  10. #10
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    Quote Originally Posted by pd406
    I don't understand... I have a lefty fork, the clamps are bonded on the lefty "shaft". with all the different headtube sizes out there How can I ever possibly get a tight fit. I'm confused.
    It is a combination of the headtube length, headset stack height and spacers. Some combinations just may not work out but most will.

  11. #11
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    hssp, quick question. Did you split the lower bearing race?
    If not it may not have slid completely down on the steerer tube causing
    the increased stack dimension.

    If that's not the issue I would recomend a shorter stack headset. The
    king is one of the taller ones @ 31.4 so i'ts not hard to find one shorter.
    Cane Kreek is doing a good job making headsets these days.

    If you are only 1.5mm inside that leaves you with 11.2mm of clamping area.
    I don't think that will be a problem for a couple rides. It probably would never
    be a problem but I think it would be worth fixing once you get back from your trip.
    Jake
    Project321
    877-584-7321
    http://www.project321.com/

  12. #12
    Mr. Knowitall
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    Thanks Jake!

    I split the lower race, yes. Guess the stack height didn't take the baseplate into account

    I have already talked to the distributor of Acros here in Norway, as they are having a stand at this event, so I will go for the first ride and then change it afterwards Trading American precision to German precision shouldn't be much of a fuss...

    Now I just need to learn how to set the spring preload. Toolshopping coming up!

    This is why I rather buy Project 321 than the Lefty 4 All steerer. Superb customer support!

  13. #13
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    For this application the Acros headset is a bad fit. The lower bearing race is so
    thin that the bearing is allowed to slide down far enough to hit the press fit diameter
    for the bearing race. Then it wont seat against the bearing plate. I just ran into this
    problem on a couple builds. And just for the record I really like the Acros product.
    It just doesn't fit well with this setup.
    Jake
    Project321
    877-584-7321
    http://www.project321.com/

  14. #14
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    Another option would be to machine of a few mm from the top of the king
    headset. A local machinst would probably do it for a good six pack of beer.
    You got good beer in Norway? Kidding of course!
    Jake
    Project321
    877-584-7321
    http://www.project321.com/

  15. #15
    Mr. Knowitall
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    In Norway we have REAL beer, so that shouldn't be a problem. Do not like fiddling too much with my CK set, I will however review the Acros sets, as they have different models, and I might be lucky Really appreciate the input, Jake! Now it is off to bed and getting stoked for tomorrow's first ride with a Lefty Max on my already perfect bike

  16. #16
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    Enjoy!
    Jake
    Project321
    877-584-7321
    http://www.project321.com/

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