Two-bolt or four-bolt stems?
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  1. #1

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    Two-bolt or four-bolt stems?

    Is it OK to use a regular two-bolt aluminum stem (such as a Profile Design H2o) for clamping 31.8 carbon fiber handlebars? Are four-bolt stems better? Should I tighten the bolts until I hear a "cracking" or "crunching" sound (Just kidding!) Thanks very much for your advice!

  2. #2
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    2-bolt OK, 4 is better...

    A 2-bolt stem will generally have larger M6 bolts that can be tightened more, but the 4-bolt models do a better job of distributing the clamping forces.

    Use of a torque wrench is a good idea, particularly if you don't have a good feel for the appropriate torque.

    http://www.boltdepot.com/fastener-in...ed-Torque.aspx

  3. #3
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    According to Easton

    Quote Originally Posted by Wisbiker
    Is it OK to use a regular two-bolt aluminum stem (such as a Profile Design H2o) for clamping 31.8 carbon fiber handlebars? Are four-bolt stems better? Should I tighten the bolts until I hear a "cracking" or "crunching" sound (Just kidding!) Thanks very much for your advice!
    It appears that Easton is in the "Two Bolt" camp.

    http://www.eastonbike.com/downloadab...ess%20Tech.pdf

    Bryan

  4. #4
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    interesting...

    My experience with 2-bolt models has never been as good as the 4-bolt. I've had problems with the bars slipping that I never have with the 4-bolt. Easton's new design may indeed work better than other 2-bolts, like the ITM's (which always slipped on me). Any owners with expereince?

  5. #5

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    I use the ITM Millennium Carbon OS 2-bolt type on my road bikes. Never experienced any slipping in combination with the Millennium Carbon 31.8 bars. I do however make sure that the contact surfaces of both bar and stem are free of burrs and grease.

  6. #6

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    I think Easton is just trying to sell their stuff. They had their 2 bolt stems on the market long before they crafted that marketing spiel.

  7. #7
    Ya, what ATP said...!
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    Quote Originally Posted by C-40
    Any owners with expereince?
    I'm using the Cinelli Solida/o Mag combo (a 2 bolt pattern) and haven't had any trouble. Though the bars are a carbon wrap over the standard aluminum Solida bar. Very stiff combo and pretty comfy.

  8. #8

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    Cleaning is key...

    It is recommended by Barnett with ALL stems that you clean the contact surfaces on the handlbar and the inside of the stem mounting surface with rubbing alcohol or acetone (well ventilated area, yada yada). This is contrasted with the seat post in the seat tube, which should be lubed to prevent seizing.

    This will clean any contaminants or grease that could tend to increase slippage.

    But certainly a four-bolt system divides clamping forces more evently. If you are of substantial weight and tend to climb out of the saddle and push down on the bars, I can't see a two-bolt system as ideal.

    Also, when tightening, you want to tighten in a crossed-X pattern in a four-bolt clamp. Do NOT tighten to recommended torque on one bolt, then move to the next one. This applies uneven clamping force. I tighten all four to 10 in-lbs under recommended, then go to five under, then to recommended. Takes an extra one minute, but well worth it.

    And this is DEFINITELY a time when you want a torque wrench. Strip these bolts and you've got BIG problems.

  9. #9

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    Two on a Road Bike is fine. .

    Quote Originally Posted by Wisbiker
    Are four-bolt stems better?
    Four bolt stems are overkill on a road bike. . they really belong on mountain bikes. I have had (have) both. A Ritchey WCS and a Easton 2-bolt. They both work just fine. .

  10. #10
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    With a four bolt stem, it's easy to screw up and tighten the bolts too much. If you use a torque wrench ( or are careful ), a four bolt stem will be fine.
    If your opinion differs from mine, ..........Too bad.
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