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  1. #1
    Lucky 47 crash66's Avatar
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    Existing headset cap incompatible with new stem??

    I have an '05 Specialized Allez Elite. Wanted to swap the Specialized house-brand stem out for an Easton EA70, but it seems the top cap (right name?) on the headset is far too broad. There is an overlap of at least 1/8th of an inch on one side, even more on the other. Further, it appears on the underside of the cap, there is a secondary circular ridge that probably fit into the circular hole on the original stem. This might be why the cap now appears off-center--the ridge appears to have "found its proper place" on one side, but not the other. If I expand the part of the stem that grabs the steerer tube enough, I'm sure I can get the top cap to "seat" properly, but then obviously the stem won't be securing the steerer tube tightly enough.

    I've cranked the cap down as far as it will go, but it's not exactly attractive, and worry about the safety aspect.

    The only thing that I can think of is that there was a insert in the original Specialized stem, that allowed for additional stem angles. Is it possible that my steerer tube is actually a 1" (hard to believe on a modern fork, but then again it is a Specialized fork and may have been made 1" to accept the nutty custom angled stem). If that's the case, I would need to use the shim that came with my Easton, no? If that's not it, I don't know what else to try. Would I need a new top cap? Do they even sell such a thing?

    Thanks for any ideas.
    Has anyone else noticed that 47 is a magic number?

  2. #2
    Senior Member mechBgon's Avatar
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    1) with the stem's clamping bolts relaxed, it should slide onto the steer tube with zero visible clearance. If you can just drop it onto the steer tube and it rattles around loose and has a big gap, then guess what... you use the shim that the new stem came with.

    2) if you should've used the shim, but you did not, then throw the new stem away and buy another one, because closing a 1/8" gap by brute-forcing the clamp bolts is the end of you being able to trust the stem, safety-wise.

    3) the top cap on an Ahead-type headset is there primarily to pre-load the fork bearings with, not to keep the stem on. Once the stem has been clamped to the steer tube (properly), you could remove the top cap and it wouldn't make it any less safe.

  3. #3
    Senior Member Brian's Avatar
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    The top cap does not affect safety in any way. Get yourself a purty new one and go enjoy your bike.

  4. #4
    Senior Member sydney's Avatar
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    Quote Originally Posted by crash66
    I have an '05 Specialized Allez Elite. Wanted to swap the Specialized house-brand stem out for an Easton EA70, but it seems the top cap (right name?) on the headset is far too broad. There is an overlap of at least 1/8th of an inch on one side, even more on the other. Further, it appears on the underside of the cap, there is a secondary circular ridge that probably fit into the circular hole on the original stem. This might be why the cap now appears off-center--the ridge appears to have "found its proper place" on one side, but not the other. If I expand the part of the stem that grabs the steerer tube enough, I'm sure I can get the top cap to "seat" properly, but then obviously the stem won't be securing the steerer tube tightly enough.

    I've cranked the cap down as far as it will go, but it's not exactly attractive, and worry about the safety aspect.


    The only thing that I can think of is that there was a insert in the original Specialized stem, that allowed for additional stem angles. Is it possible that my steerer tube is actually a 1" (hard to believe on a modern fork, but then again it is a Specialized fork and may have been made 1" to accept the nutty custom angled stem). If that's the case, I would need to use the shim that came with my Easton, no? If that's not it, I don't know what else to try. Would I need a new top cap? Do they even sell such a thing?

    Thanks for any ideas.
    The topcap does not secure the stem. It and the bolt thru it are used to adjust the bearing prelaod with the stem to steerer clamp bolts loosened. Once preload is set and the bolts tightened, you could remove and throw the topcap away.

  5. #5
    Senior Member Brian's Avatar
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    Quote Originally Posted by sydney
    The topcap does not secure the stem. It and the bolt thru it are used to adjust the bearing prelaod with the stem to steerer clamp bolts loosened. Once preload is set and the bolts tightened, you could remove and throw the topcap away.
    Rule number of of being a true cycling enthusiast: Throw nothing away. Ever.

  6. #6
    mousse de chocolat Moose's Avatar
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    Is the top cap hitting the steerer tube? Did you remove any spacers or is the EA70 not as tall as the stock stem? A 1 1/8" top cap should fit into any 1 1/8" stem.

  7. #7
    Lucky 47 crash66's Avatar
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    Mech and sydney,
    Thanks for the info. It turns out my steerer tube is 1 1/8", so the issue was simply that the Specialized top cap needed to be rotated a certain way and then seated much better (the hole was designed off-center, so the "long" part of the cap--from the hole-- needed to be situated forward, as opposed to left or right. Duh.)

    However, your responses about tightening the top cap before cranking down the stem bolts was definitely something this novice didn't know. So I will immediately loosen the stem, preload the bearings with the the cap, and retighten the stem. I was wondering why my spacers kept spinning no matter how much cranked the cap down.

    Thanks all.
    Has anyone else noticed that 47 is a magic number?

  8. #8
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by crash66
    Mech and sydney,
    Thanks for the info. It turns out my steerer tube is 1 1/8", so the issue was simply that the Specialized top cap needed to be rotated a certain way and then seated much better (the hole was designed off-center, so the "long" part of the cap--from the hole-- needed to be situated forward, as opposed to left or right. Duh.)

    However, your responses about tightening the top cap before cranking down the stem bolts was definitely something this novice didn't know. So I will immediately loosen the stem, preload the bearings with the the cap, and retighten the stem. I was wondering why my spacers kept spinning no matter how much cranked the cap down.

    Thanks all.
    You need more spacers under the stem. The top of the stem should be a few millimeters higher than the steer tube. DO NOT RIDE THE BIKE before you get the correct number of spacers! You have no load on the bearings now and the steerer will move up and down and could damage the bearings or the fork.
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  9. #9
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    I'd get a new top cap.

    The Specialized topcaps, like you said, are machined off center to accomidate their 4 postion stems. I've yet to find a 'normal' stem which looks good with the Specialized topcap. This is only asthetics though.

  10. #10
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    Once the headset bearing pre-load is set correctly, the the whole pressure nut assembly has no purpose. I took mine out and replaced it with a cap from the hardware store. It cost 45 cents and saved 40 grams. I wish I had had $45 in my pocket at the hardware store that day, I could have saved 9 pounds.
    The Easton website has something call a "beartrap." It's an adjustable height spacer that sets the pre-load without a pressure nut inside the steerer. It seems pointless since you can just remove the nut to get that weight saving, but it supports the idea that you don't need the compression nut inside the steerer.

    em
    Last edited by eddy m; 11-20-05 at 08:13 AM.

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