I ride a Giant road bike with OD2 carbon steerer. It was originally built up with a standard expander plug, but was supplied with the glue-in Aircap expander as well. Im not sure whether to use it and there is very little information about these online.

I've only been able to find two things about it so far. Apparently it's a bit lighter, but I couldn't find how much lighter. It seems to also be a lot more hassle if you install it then want to cut the steerer again. If that's the only downside to it, then I'm happy to use it because my steerer is already cut down to have no spacers underneath. Is there anything else that should affect my decision to use this or not?

  • Impossible to over-torque and damage CFC steerer? Commented Jan 14, 2019 at 17:03
  • I understand that you always need at least one spacer above and below, even if its only a 2mm.
    – Criggie
    Commented Nov 25, 2019 at 8:55

2 Answers 2


The weight savings is 30grams, aircap 15g, original 45 grams.

  • The numbers are great, but it would be even better if you could supply references for them...
    – DavidW
    Commented Nov 25, 2019 at 14:38

Many people tend toward a "if it ain't broke, don't fix it" mindset with bicycles. I think you already understand the main differences (weight, inability to shorten steertube after installation). The only other immediate difference is cost (money for a new expander, versus the one you already own) and labor.

One other difference may be that if that fork is somehow damaged/destroyed, you'll likely lose the glue-in, however, you have original as backup in that case. Really it's just a case of you deciding to spend the money to save a few grams (that's assuming the glue doesn't make up the weight difference and make it the whole thing just a marketing gimmick).

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