Normal for stem not to close fully?

Bike-Rich
Bike-Rich Posts: 275
edited March 2012 in Workshop
Hi all,

Something I have always noticed on my road bike is that the stem to bar clamp never closes fully, is this normal? I never get any 'slips' or have the need to re-tighten on rides. It just I would of thought that clasp would of closed fully but it does not no matter how hard I tighten bolts:

IMG_2520.jpg

Comments

  • kettrinboy
    kettrinboy Posts: 613
    Yes its normal, if there wasnt a gap when fully tightened up the bars would likely slip, i do try to keep the gap equal top and bottom though to even out the stress on the top and bottom bolts
  • Bike-Rich
    Bike-Rich Posts: 275
    Perfect, thanks for help :) I will retighten to ensure stress is equal also.

    Also, looking at the picture. What size would you say my handle bar is? Oversize?
  • sungod
    sungod Posts: 16,845
    it's oversize 31.8mm (1.5")

    when clamping, make sure the surfaces are clean, then do up bolts a bit at a time to even out the force over the faceplate

    for instance, the four bolts viewed from front...

    1 - 2
    |....|
    3 - 4

    ...do them up in this order 1 4 2 3, start finger tight, then give each a half turn, then move on to the next bolt, repeat until you reach enough force to clamp the bars, 5-6Nm is usually plenty - if doing it by feel, do quarter turns, and test the bars after each 1423 'lap' until they are tight, it does not take a lot to clamp them securely
    my bike - faster than god's and twice as shiny
  • Bike-Rich
    Bike-Rich Posts: 275
    Many thanks for reply, and advice.

    So is 'oversize' always classed as 31.8? I know there are other common sizes like 26.4 and 31.6, but is it 31.8 that is oversize only?

    Also, when you say 5-6nm is this by general 'feel'? I have a good halfords pro socket set but do not have a gauge measurement - do you think it is a good ideal to get one?
  • desweller
    desweller Posts: 5,175
    If you don't have any natural feel for torque then get a torque wrench. You can damage the bars if you overtighten the faceplate screws.
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  • andy46
    andy46 Posts: 1,666
    Torque wrenches can be quite expensive so the Ritchey Torque Key can be a good investment.

    http://www.chainreactioncycles.com/Mode ... elID=39478
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  • sungod
    sungod Posts: 16,845
    Bike-Rich wrote:
    Many thanks for reply, and advice.

    So is 'oversize' always classed as 31.8? I know there are other common sizes like 26.4 and 31.6, but is it 31.8 that is oversize only?

    Also, when you say 5-6nm is this by general 'feel'? I have a good halfords pro socket set but do not have a gauge measurement - do you think it is a good ideal to get one?

    by feel, just tighten evenly, in small increments, when you reach the point where you can't turn the bars in the stem, it's tight enough - i used to do it this way with alloy bars, with cf i use a torque wrench

    for road bikes, the older standard was 26mm, but there were variations

    today, oversize means 31.8mm (except deda who choose to be different with 31.7mm, but they're still compatible)

    31.6mm is a seatpost size, don't remember seeing it used for handlebars
    my bike - faster than god's and twice as shiny
  • Bike-Rich
    Bike-Rich Posts: 275
    Perfect, thanks for help :) I understand now.

    Also, for a mountain bike do you think straight bars are better then 'riser' or 'monkey bars'?
  • JamesB
    JamesB Posts: 1,184
    Also, for a mountain bike do you think straight bars are better then 'riser' or 'monkey bars'?

    I`ve used both on my MTB and apart from difference in width I`m unsure that there is any difference in handling between say a flat bar with extra spacers under stem and a riser bar set at same bar end height; it is interesting to see now that extra wide flat bars are coming into fashion. eg http://www.chainreactioncycles.com/Mode ... elID=41039 super wide XC bars

    So IMO risers may just be a passing fad