Specialized headset spacers - techie question

meggiedude
meggiedude Posts: 257
edited September 2010 in Workshop
Ok, so I have taken delivery of my Specie Allez Comp and overall I am very pleased.
However I need to install a 110mm stem and at the same time I'd like to lower the handlebars.
The Allez range come with 3 spacers set below the stem and the stem angle set at -8deg by default. By rotating the shim I can get the angle to -16deg which is a start, but since I have the spacers I was going to move 2 or 3 of the spacers above the stem to see what that is like.
However with the Specie fork installation guide that came with the bike it comes with the warning, and I quote
"Warning!, Do not permanently place stem spacers above the stem. Placing spacers above the stem defeats the purpose of the expander plugs ability to support the stearer tube and stem"
There's then a nice little right and wrong diagram (spacers below stem = tick, spacers below = cross).
There are also instructions about sawing bits of the carbon steerer as the 'perninent' fix, which I am reluctant to do for obvious reasons.

This is my first recent 'modern' carbon forked bike, my others being 'old school' quill stems, which don't have this restriction. So any advice on what to do here would be appreciated. I went into a local bike shop yesterday and there were loads of bikes (no specialized) in the store setup with spacers above the stem. Why is this an issue for Specialized??
Can I upgrade???

Comments

  • sungod
    sungod Posts: 16,849
    it's a carbon steerer thing, rather than specific to specialized

    perhaps the bikes with spacers above the stem have alloy steerer tubes

    if you put spacers above the stem, the expander plug will no longer be positioned inside the tube at the same position that the stem clamps the tube

    the expander plug prevents the carbon steerer tube being distorted/crushed by the stem

    without the plug to support it, the lower edge of the stem may put a concentrated load on the steerer tube, eventually this could cause catastrophic failure
    my bike - faster than god's and twice as shiny
  • softlad
    softlad Posts: 3,513
    in practice, it's not a major issue. you don't need a huge amount of force to secure the expander plug in the steerer, so the risk of failure through having a spacer above the stem on a carbon steerer is relatively minor. Either way, it sounds like you will have to cut the length of the steerer anyway to remove the excess - a bike shop will do this for you if you're not confident, but I used a jig saw on mine. The hard part is measuring it correctly in the first place...
  • sungod wrote:
    it's a carbon steerer thing, rather than specific to specialized

    perhaps the bikes with spacers above the stem have alloy steerer tubes

    if you put spacers above the stem, the expander plug will no longer be positioned inside the tube at the same position that the stem clamps the tube

    the expander plug prevents the carbon steerer tube being distorted/crushed by the stem

    without the plug to support it, the lower edge of the stem may put a concentrated load on the steerer tube, eventually this could cause catastrophic failure
    The bike shop in question was selliing new Felt and Lapierre road bikes alongside a larger stock of MTB's
    The Felt was all Carbon and the Lapierre carbon forked. It gives the bikes a more aggressive head-down setup but its a worry that some techs are setting the bikes up like this if it compromises safety.

    TBH, Bike Radar don't do themselves any credit by reviewing some of their bikes in this apparently dodgy setup - see here:
    http://www.bikeradar.com/gallery/article/specialized-allez-elite-20022?img=6&pn=allez-elite-09&mlc=gear%2Fbikes%2Froad%2Farticle

    Full article here:
    http://www.bikeradar.com/gear/category/bikes/road/product/allez-elite-09-33633

    If they setup the bikes like this for the review, others will think its a safe config for their own bike.

    MD
    Can I upgrade???
  • softlad
    softlad Posts: 3,513
    meggiedude wrote:
    but its a worry that some techs are setting the bikes up like this if it compromises safety.

    it doesn't compromise safety. it just looks naff.

    edit - I just re-read your original post. For some reason I was thinking you were looking at cutting a full length un-cut steerer, as opposed to one already fitted and sized correctly. You won't have any issues running a single spacer above the stem, for the reasons I mentioned earlier. Although the more you have on top, the sillier it looks.....
  • softlad wrote:
    meggiedude wrote:
    but its a worry that some techs are setting the bikes up like this if it compromises safety.

    it doesn't compromise safety. it just looks naff.

    edit - I just re-read your original post. For some reason I was thinking you were looking at cutting a full length un-cut steerer, as opposed to one already fitted and sized correctly. You won't have any issues running a single spacer above the stem, for the reasons I mentioned earlier. Although the more you have on top, the sillier it looks.....

    No I don't want to cut it, if at all possible. I worry less about how silly some people may consider it looking. More concerned about safety.
    sungod's post above pretty much sums up what the Specialized instructions state.
    This has got to to a safety concern hasn't it??

    Below is the instruction sheet I have been provided with. Note bit at bottom left of page 1 and the diagrams on right of page 1.
    http://cdn.specialized.com/OA_MEDIA/pdf/manuals/08_Fork_Installation_Guide_r2.pdf

    MD
    Can I upgrade???
  • softlad
    softlad Posts: 3,513
    I don't think it's a safety concern, for the reasons I mentioned earlier. I know what Spec's safety instructions are like, because I built up a Tarmac frame recently. I really don't think satefy is a major concern here and I suspect their instructions have more to do with the US litigation system than any sound practical advice. FWIW I'm running a 5mm spacer above my stem on the carbon steer on my tarmac...
  • softlad wrote:
    I don't think it's a safety concern, for the reasons I mentioned earlier. I know what Spec's safety instructions are like, because I built up a Tarmac frame recently. I really don't think satefy is a major concern here and I suspect their instructions have more to do with the US litigation system than any sound practical advice.
    Yes this did cross my mind, the several references to serious injury or death(!!!) in the brochure back this up.
    softlad wrote:
    FWIW I'm running a 5mm spacer above my stem on the carbon steer on my tarmac...
    Now thats just going to look plain naff...........

    Sorry couldn't resist it.
    .
    .
    .
    I'll get me coat.

    MD
    Can I upgrade???
  • softlad
    softlad Posts: 3,513
    meggiedude wrote:
    Now thats just going to look plain naff...........

    Sorry couldn't resist it.

    20/30mm above looks naff - 5mm is hardly noticeable.. ;)
  • The expander plugs are only used in forks with carbon steerers as far as I know.

    The Allez always used to have an aluminium steerer tube, with a conventional star fangled nut inside. The 2011 model still uses an aluminium steerer according to the website.

    In which case, you can run pretty much whatever spacer combination you like.
    Alex
  • 2alexcoo wrote:
    The expander plugs are only used in forks with carbon steerers as far as I know.

    The Allez always used to have an aluminium steerer tube, with a conventional star fangled nut inside. The 2011 model still uses an aluminium steerer according to the website.

    In which case, you can run pretty much whatever spacer combination you like.
    Ah, OK, so I am looking for an aluminium steerer (bonded to carbon forks I guess) together with an ally star nut. If I see a steerer tube plug/expander-bolt then I am all carbon.

    Cheers

    MD.
    Can I upgrade???
  • sungod
    sungod Posts: 16,849
    softlad wrote:
    it doesn't compromise safety. it just looks naff.

    <...>
    .

    specialized are quite clear on the matter, they explicitly say it does compromise safety...

    http://cdn.specialized.com/OA_MEDIA/pdf ... ide_r2.pdf

    steerer tube failure is always going to be nasty, going face first into the tarmac at speed doesn't bear thinking about, you'd be crazy to ignore the manufacturer's advice on this
    my bike - faster than god's and twice as shiny
  • softlad
    softlad Posts: 3,513
    sungod wrote:

    specialized are quite clear on the matter, they explicitly say it does compromise safety...

    http://cdn.specialized.com/OA_MEDIA/pdf ... ide_r2.pdf

    steerer tube failure is always going to be nasty, going face first into the tarmac at speed doesn't bear thinking about, you'd be crazy to ignore the manufacturer's advice on this

    We've already covered this. I'll take the risk, thanks...
  • sungod wrote:
    softlad wrote:
    it doesn't compromise safety. it just looks naff.

    <...>
    .

    specialized are quite clear on the matter, they explicitly say it does compromise safety...

    http://cdn.specialized.com/OA_MEDIA/pdf ... ide_r2.pdf

    steerer tube failure is always going to be nasty, going face first into the tarmac at speed doesn't bear thinking about, you'd be crazy to ignore the manufacturer's advice on this
    Softlad is clearly a little braver than I - maybe he should change his username :wink:

    That said if 2alexcoo is correct (I've checked the Allez specs and I think he Is) then I have carbon forks with an ally steerer.
    As Lewis Hamilton found out at the weekend, Carbon fibre, while incredibly strong under designed loading, is somewhat fragile in any other loading condition. Ally tubing is a little more forgiving.
    So should I still have the same concern wrt spacers above the stem, aside from the obvious and subjective aesthetic concern that is.

    If the answer is - 'Yes, you're a fool to take the risk', then I stick by my point above that Bikeradar should not be publishing reviews with the steerer set up like this.

    I know we've already covered this softlad, but my setup is somewhat different to what I originally thought. I am also a little less cavalier when it comes to the condition of my face, shoulder blades etc. Just my opinion - sorry.

    MD
    Can I upgrade???
  • softlad
    softlad Posts: 3,513
    clearly if you have the stem set up like the pic in the Specialized instructions, then you would need your head examined anyway. But like I said, I have a 5mm spacer above the stem, with no more than 2mm of the steerer protruding above. None of the 'expanding' part of the expander bolt assembly is above the stem - so it's a total non issue as far as I'm concerned.

    And as I said at the start, unless you are a total gorilla with no sense of mechanical sympathy, you do not need to wind the expander bolt up too tight in order for it to grip the inside of the steerer securely. It only has to be tight enough to stay put and support enough pressure (via the cap bolt) on the top headset bearing to remove any play in the steerer - that's all. It's hardly structural.....
  • flasher
    flasher Posts: 1,734
    sungod wrote:
    softlad wrote:
    it doesn't compromise safety. it just looks naff.

    <...>
    .

    specialized are quite clear on the matter, they explicitly say it does compromise safety...

    http://cdn.specialized.com/OA_MEDIA/pdf ... ide_r2.pdf

    steerer tube failure is always going to be nasty, going face first into the tarmac at speed doesn't bear thinking about, you'd be crazy to ignore the manufacturer's advice on this

    However the .pdf also says:

    "Unless the desired stem height is already determined, it is recommended that the initial installation of the fork be done with the maximum allowed stack height (40mm) to allow the greatest range of adjustability. Spacers can be placed above or below the stem to adjust your position. Once a more precise stem height is determined, a second cut can be made to eliminate any spacers that may have been placed above the stem to achieve the desired position."