Stem advice - are 4 bolts really necessary?

KonaKurt
KonaKurt Posts: 720
edited November 2009 in MTB workshop & tech
I'm just looking for some quick opinions. The only weak point I consider my bike to have is possibly the stem. It is a TWO bolt EA50 but has served me well up to now for basic XC and trail riding. I'm just wondering how much stronger a 4 bolt EA50 would be in comparison? What exactly are TWO bolt stems designed for in terms of punishment?

KK.

Comments

  • nicklouse
    nicklouse Posts: 50,673
    generally XC.

    but it does depend on the stem and its design.

    Titec did some very strong 2 bolt design which were goog for most things.

    So what stem do you have now?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • KonaKurt
    KonaKurt Posts: 720
    I have a 2006 Easton EA50 (two bolt). With 0 degree rise and 130mm long. I need the length because I am tall. It's well fitted and kept nice and tight, but I sometimes 'feel' it flexing very slightly on big hits out on the trails.

    KK.
  • The Rookie
    The Rookie Posts: 27,812
    A 2-bolt will always be more flxible than a 4, its physics, and a 130 will be more flexible than a 100......

    Shorter bars will reduce the flex in the bars and also reduce any effect of unequal pressure on them resulting in a twist being put on the stem.

    Otherwise you'll have to consider a stiffer stem, especially if your a big 'un!

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • KonaKurt
    KonaKurt Posts: 720
    I am a bit of a big 'un!

    I'm not going to panic about having a 2 bolt because it's done me proud so far. But if something goes wrong I'll rush to the shops for a 4 bolt.

    KK.
  • k2rider
    k2rider Posts: 575
    2 bolt stems generally have bigger bolts in them holding on the faceplate, usually m6 or ive even seen m8, the four bolt stem usually has m5, trouble with the 4 bolt stem its a lot easier to strip the thread of a smaller tapped hole in aluminium than it is with a bigger hole even if its only 1mm bigger they also need more careful tightening than a 2 bolt stem, the reason you say it flexes has nothing to do with the 2 or 4 bolt faceplate its all down to the length of the stem.
    who cares?
  • hoathy
    hoathy Posts: 776
    genrally speaking and in my experience - weighing 18stone - 2 bolt stems flex more, but it does vary on a case to case basis, I used to have a 120mm Eastons EA50 2 bolt, and it was more flexy than the RaceFace 4 Bolt I replaced it with, I have also strugged with stems clicking and creaking with a bolt EA70 and a Bontrager Race X.

    Of course bar width and type also make a big difference, but i have always found easton bars to be amongst the best.
    - Kona Hot '96 - Marin Rift Zone '09 - Cannondale Synapse Carbon '06 - Kona Caldera '98 - Kona AA '94 - Dawes Kickback II - Cannondale BadBoy '11 - Genesis iOiD SS -
  • nicklouse
    nicklouse Posts: 50,673
    As k2rider says it comes down to the design.

    some 4 bolts are not as strong as some 2 bolts etc etc...
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • KonaKurt
    KonaKurt Posts: 720
    ok, thanks everyone. :)

    I don't think the 'flex' I sometimes feel is down to the length of the stem, though I admit it's a long one. My Easton bars are as solid as I could wish them to be, so the flex is definatly at the faceplate.

    All the same, no worries :)

    KK.

    PS: My bolts are M6 bolts.

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