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FSA compression plug

chatlowchatlow Posts: 825
edited August 2018 in Workshop
Just bought a lovely 2015 Canondale supersix evo but I am baffled by the headset. Had the change the stem but then found it's using an FSA compressor top cap.

Never used one before but youtube seemed to show something similar and I ended up using a 5mm key to tighten/expand the compressor inside the tube (to around 5nm) then tightened the top cap further with a 6mm key until snug and no movement in the headset.

Took a few attempts (and the compressor fell down the fork twice) but can someone just let me know if I've done the right thing as I am paranoid.

Posts

  • chatlow wrote:
    Just bought a lovely 2015 Canondale supersix evo but I am baffled by the headset. Had the change the stem but then found it's using an FSA compressor top cap.

    Never used one before but youtube seemed to show something similar and I ended up using a 5mm key to tighten/expand the compressor inside the tube (to around 5nm) then tightened the top cap further with a 6mm key until snug and no movement in the headset.

    Took a few attempts (and the compressor fell down the fork twice) but can someone just let me know if I've done the right thing as I am paranoid.

    If it’s using a compressor plug it’s in place of a star spangled nut. If you can’t get the compressor plug to work see if you can get a star nut that fits in the steerer.
  • timothywtimothyw Posts: 2,482
    If it’s using a compressor plug it’s in place of a star spangled nut. If you can’t get the compressor plug to work see if you can get a star nut that fits in the steerer.

    Definitely don't do that if it is a carbon steerer tube.

    Star nuts are only for use in metal fork steerers. Expander bungs can be used in any kind of fork.
  • TimothyW wrote:
    If it’s using a compressor plug it’s in place of a star spangled nut. If you can’t get the compressor plug to work see if you can get a star nut that fits in the steerer.

    Definitely don't do that if it is a carbon steerer tube.

    Star nuts are only for use in metal fork steerers. Expander bungs can be used in any kind of fork.

    True, all my steerers are alloy. If it’s a carbon steerer stick to expander plugs.
  • chatlowchatlow Posts: 825
    Okay, So... the way I have fitted - does it sound okay? Feels good so hoping so.
  • chatlow wrote:
    Okay, So... the way I have fitted - does it sound okay? Feels good so hoping so.

    If the bars are staying put and there’s no back and forward play in the forks to headset you’ve got it right.
  • drexel1975drexel1975 Posts: 69
    chatlow wrote:
    Okay, So... the way I have fitted - does it sound okay? Feels good so hoping so.
    As long as the compression plug is where the stem clamps then all is good.
  • keef66keef66 Posts: 13,123
    Your description sounds like the bung I got with my Scott frameset but with the allen keys the other way round. Tightened it inside the steerer with a 6mm, then the top-cap with a 5mm. After the shakedown ride and final adjustment of the headset bearing preload I removed the top-cap again and tightened up the bung a bit more since the steerer was by then clamped by the stem. Been rock solid for 5 years
  • Vino'sGhostVino'sGhost Posts: 4,129
    chatlow wrote:
    Okay, So... the way I have fitted - does it sound okay? Feels good so hoping so.

    It’s the correct way yes.
  • chatlowchatlow Posts: 825
    resurrecting the thread because my headset developed a creek yesterday. I have undone the top cap and tightened the plug a little more, before tightening the cap and clamp bolt. Creak is better but remains.

    When I put down on the handlebars, the creek isn't there when the stem clamp bolts are loose, but once tightening again, it comes back.

    Any thoughts?

    BTW, the compressor plug is tightened to ~4nm and the top cap needed tightening to the same to stop any play. I am wondering if having a small spacer above the clamp bolts might be causing this.

    thanks,
  • jgsijgsi Posts: 5,029
    Very quick headset compliance test
    Front brake on , grab the bars and try to move the bike back and to - any movement in the front end?
    Yes ..means your headset needs attention - all the bits of it.
  • chatlowchatlow Posts: 825
    JGSI wrote:
    Very quick headset compliance test
    Front brake on , grab the bars and try to move the bike back and to - any movement in the front end?
    Yes ..means your headset needs attention - all the bits of it.

    The headset is tight, no movement at all and has been that way since fitting the plug a few weeks ago. My issue is creaking within the headset when putting weight on the handlebars
  • Carbon has a tremendous ability to transmit creaking sounds so check all material contact points.

    I had a creaking that seemed to be coming from a contact point on the carbon bars, either the stem or a brake lever, but it turned out to be the wheel in the dropouts.
  • QR skewers and the points where spokes cross over on wheels are notorious points for creaks, which as said above can transmit through carbon quite nicely, leading you to believe the creak is coming from somewhere it isn’t.
  • keef66keef66 Posts: 13,123
    Carbon paste near headset bearings and spacers is also not a great idea.....
  • chatlowchatlow Posts: 825
    the creaking it definitely from the headset. It's silent when the top cap and stem bolts are loosened. Perhaps tightening the plug over 5nm might fix, I was just worried as it's carbon.

    It's a lot better now, but still creaks if I put weight on the bars so I guess would notice when putting the power down
  • imposter2.0imposter2.0 Posts: 11,382
    chatlow wrote:
    the creaking it definitely from the headset. It's silent when the top cap and stem bolts are loosened. Perhaps tightening the plug over 5nm might fix, I was just worried as it's carbon

    The expander plug only has to be tight enough to pull down on the headset without slipping. If it is doing that, then tightening it more will not make any difference.
  • Imposter wrote:
    chatlow wrote:
    the creaking it definitely from the headset. It's silent when the top cap and stem bolts are loosened. Perhaps tightening the plug over 5nm might fix, I was just worried as it's carbon

    The expander plug only has to be tight enough to pull down on the headset without slipping. If it is doing that, then tightening it more will not make any difference.
    Indeed.

    Loading up the bearings unnecessarily making for some stiff steering.
  • chatlowchatlow Posts: 825
    Imposter wrote:
    chatlow wrote:
    the creaking it definitely from the headset. It's silent when the top cap and stem bolts are loosened. Perhaps tightening the plug over 5nm might fix, I was just worried as it's carbon

    The expander plug only has to be tight enough to pull down on the headset without slipping. If it is doing that, then tightening it more will not make any difference.

    that's what I thought and followed a setup guide which suggested around 4nm which I stuck too.

    as for the top cap, on my other non-plug type headsets, I would normally go for just over finger tight but there's still lots of play with this type and it has to be around 3-4bnm to stop any play.

    Bl00dy creaks :roll:
  • imposter2.0imposter2.0 Posts: 11,382
    Please stop mentioning torque numbers, they are irrelevant. Obviously if you tighten something, it will be tightened to a certain torque, but in this case the actual number is incidental. Some top caps might need more, others will need less. Let's leave torque out of this discussion.
  • chatlowchatlow Posts: 825
    Imposter wrote:
    Please stop mentioning torque numbers, they are irrelevant. Obviously if you tighten something, it will be tightened to a certain torque, but in this case the actual number is incidental. Some top caps might need more, others will need less. Let's leave torque out of this discussion.

    How so? Tightening the expander plug just enough so that it's sat in the head tube is a lot different to 5+nm - so I just wanted to check it hadn't been overtightened and the cause of the creak.
  • keef66keef66 Posts: 13,123
    chatlow wrote:
    Imposter wrote:
    Please stop mentioning torque numbers, they are irrelevant. Obviously if you tighten something, it will be tightened to a certain torque, but in this case the actual number is incidental. Some top caps might need more, others will need less. Let's leave torque out of this discussion.

    How so? Tightening the expander plug just enough so that it's sat in the head tube is a lot different to 5+nm - so I just wanted to check it hadn't been overtightened and the cause of the creak.

    He meant with reference to tightening the top cap. Although it appears some manufacturers do specify a value even for that.

    I doubt overtightening the bung in the steerer would be the cause of a creak unless you'd really overdone it and split the carbon. Once the stem is clamping the steerer you could always whip the top cap off and remove the bung to see if it makes any difference to the creaking?

    The expander bung needs to be tight enough in the steerer so that it's not pulled up as you tighten the top cap bolt. Some manufacturers give a range of torque values, some a maximum. It's helpful if the makers of the fork, bung and headset all agree, but they don't always. Some require the bung to fully support the section of steerer clamped by the stem, while others don't. And there is differing advice about the size and number of spacers allowed both above and below the stem. Some insist on a spacer above because the bung sits below the top of the steerer and they fear the unsupported end could be crushed by the stem. On mine the bung sits flush with the top of the stem so the advice is no spacers above, presumably because the stem might otherwise crush an unsupported bit of steerer further down. And some seem to be concerned with the amount of flex in the steerer above the upper headset bearing.
  • chatlowchatlow Posts: 825
    thanks for that and yeah it does seem to differ a lot amongst manufacturers. Also read about spacers and trying to have the plug where the bolt clamp too, which mine is - I think. As for the top cap - the only reason I mentioned the amount needed to stop play was because it was A LOT more compared to my other setup which are little over finger tight and never had a problem with them
  • chatlowchatlow Posts: 825
    Update: refit the plug and cap a number of times until snug and no play and confirmed there's zero creak going on UNTIL I tighten up the stem clamp bolts.

    I have 1 spacer above the stem. Is it likely to be causing an issue and is there anything I can do to help fix this

    ^^ NM - I also tried fitting with no spacer above the step and it's the same situation: fine when the stem bolts are loose, creaking when tightened (and adding weight to the bars)
  • chatlow wrote:
    Imposter wrote:
    Please stop mentioning torque numbers, they are irrelevant. Obviously if you tighten something, it will be tightened to a certain torque, but in this case the actual number is incidental. Some top caps might need more, others will need less. Let's leave torque out of this discussion.

    How so? Tightening the expander plug just enough so that it's sat in the head tube is a lot different to 5+nm - so I just wanted to check it hadn't been overtightened and the cause of the creak.

    Good point well made.
  • chatlow wrote:
    Update: refit the plug and cap a number of times until snug and no play and confirmed there's zero creak going on UNTIL I tighten up the stem clamp bolts.

    I have 1 spacer above the stem. Is it likely to be causing an issue and is there anything I can do to help fix this

    ^^ NM - I also tried fitting with no spacer above the step and it's the same situation: fine when the stem bolts are loose, creaking when tightened (and adding weight to the bars)
    A bit of carbon gripper paste around the inside of the spacer might help.
  • keef66 wrote:
    Carbon paste near headset bearings and spacers is also not a great idea.....

    The paste won’t be near the bearings, it might be near the spacers but hey if it stops the creak.
  • chatlowchatlow Posts: 825
    cheers - worth a go. annoying I have to tighten the stem clamp up because the entire thing is actually solid with the them loose and also creak free!
  • Vino'sGhostVino'sGhost Posts: 4,129
    I have to agree with the idiot biker grove this time try the carbon paste.
  • imposter2.0imposter2.0 Posts: 11,382
    Should not be necessary to put carbon paste on the steerer, for any reason. If nothing has stopped the creak so far, then I would be looking closer at the steerer to see if it is cracked..
  • svettysvetty Posts: 1,904
    Hard to see that there is movement at the steerer if the stem bolts are properly tightened.....
    FFS! Harden up and grow a pair :D
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