Spacer limit for carbon steerer

bungle73
bungle73 Posts: 758
edited June 2019 in Workshop
According to the docs got I got with my new bike the safe amount of spacers on the steerer tube is 40 mm. Does this include the height of the bearing cover or not? I'm assuming to does? I want to replace the stock stem and handlebars with the Deda Superzero ones I already had. The troubler is the stem clamp om the Deda is slightly shorter than the stock one, so if I just swap them the steerer comes up too far.

I've found two ways it might work. One, the pack included a shorter bearing cover (the fitted one is quite tall), so if I use that, plus some spare spaces I have laying around, it would put the stem in correct place. Two, buy an extra 3 mm spacer to use with the original set up + Deda stem. The trouble is both these would exceed the 40 mm limit, including bearing cover.

I guess I could cut down the steerer tube, but I don't really don't want to do that. I guess my only choice would be to use the stock stem with the Deda handlebars?

Comments

  • Alejandrosdog
    Alejandrosdog Posts: 1,975
    You should take it to a professional bungle like cycleclinic or Merlin.

    I would just use the extra spacer if you need it or if your stem is at the right height without, cut the steerer down.

    Or Slam it and live with the pain.

    #slammed
  • whyamihere
    whyamihere Posts: 7,700
    Whatever you do will be fine. The 40mm guideline is to make sure you don't have a huge amount of steerer below the stem, as that acts as a big lever with the fulcrum at the top bearing, and so is more relevant when fitting a new fork. Your bike will have been supplied with a steerer which is safe with a stem right at the top of it (unless you do something stupid like put a load more spacers in so that only the bottom 5mm of the stem is clamping the steerer).
  • bungle73
    bungle73 Posts: 758
    whyamihere wrote:
    Whatever you do will be fine. The 40mm guideline is to make sure you don't have a huge amount of steerer below the stem, as that acts as a big lever with the fulcrum at the top bearing, and so is more relevant when fitting a new fork. Your bike will have been supplied with a steerer which is safe with a stem right at the top of it (unless you do something stupid like put a load more spacers in so that only the bottom 5mm of the stem is clamping the steerer).

    OK thanks, I guess that makes sense. I was just a bit paranoid about it, as you hear horror stories about carbon components if you don't respect them.
  • carl_p
    carl_p Posts: 989
    I wouldn't worry about 3mm. But for added piece of mind you could use an extra long expansion bolt to spread the load a bit.

    https://www.tredz.co.uk/.Pro-Headset-Ex ... ZEALw_wcB#
    Specialized Venge S Works
    Cannondale Synapse
    Enigma Etape
    Genesis Flyer Single Speed


    Turn the corner, rub my eyes and hope the world will last...
  • bungle73
    bungle73 Posts: 758
    I just ordered a 2 mm spacer on eBay, which by my calculations should put the stem in the correct place.
    Carl_P wrote:
    I wouldn't worry about 3mm. But for added piece of mind you could use an extra long expansion bolt to spread the load a bit.

    https://www.tredz.co.uk/.Pro-Headset-Ex ... ZEALw_wcB#

    But the stem clamp is clamping a smaller area, so surely that part wouldn't be a problem?

Categories