Headset/Expander Question

Lunty Posts: 20
edited July 2009 in Road beginners
I'm getting fed up of my headset coming loose and think I've traced the problem to my expander. What I need to know is if the measurements (either 1" or 1 1/8") for the new ones I'm looking at buying are for the internal or external diameter of the steering/fork tube.

My micrometer has the external at 0.999 inches so I think I know what I need, but can only find an M: Part expander to fit that (assuming it's the external diameter I want). I'm hesitant to use the M:Part again since the last one caused my problems...any recommendations?

Thanks in advance!


  • Smokin Joe
    Smokin Joe Posts: 2,706
    I'm assuming that by expander you mean the bung or starnut that fits in the steerer tube. If your headset is coming loose after being initially torqued down correctly that will not be the cause. Once the stem bolts have been tightened you could even remove the top cap and nut with no adverse effect.

    You need to look for another cause of the problem.
  • Infamous
    Infamous Posts: 1,130
    I don't know if this is any help, but I used the M part and it was terrible. Rounded the bolt off before I could even get it tight enough, replaced the bolt and still would never keep the headset tight. Changed it to an Easton one and it sorted it.

    If you are unsure of the size, take the old expander into a bike shop and ask for one the same size.
  • John.T
    John.T Posts: 3,698
    SJ is right. Once the stem bolts are clamped up it should not move. The cap is only for initial adjustment and a bit of insurance.