I needed to replace my broken Bontrager Satellite Plus carbon/aluminum fork on my '05 Trek 1000. I chose this Q2 carbon/ aluminum fork From auction link - avoiding link rot by inlining.

as a replacement because the few Satellite Plus forks I was able to find online had their steerers cut too short or were unacceptably marred for the asking price.

The unforeseen problem with this Q2 fork is that the crown seat is larger by 5 mm than the current lower headset, an Aheadset semi integrated, and therefore sticks out ridiculously past the the circumference of the lower head tube. See photo. What can be done to better mesh the new fork's crown to the head tube of the Trek?

I've been reviewing headsets and the SHIS system but I can't seem to hook up what is needed here. Will a "conversion " crown race work? What exactly (in SHIS nomenclature) do I need if replacing the entire lower headset is the best option? Lastly, is the crown seat diameter commonly expressed --perhaps termed something different--in the sales information of a bicycle fork? This was quite the oversight on my part having paid particular attention to steerer length, axle to crown, and the rake figures when choosing from the pool of 700c, rigid road forks.

According to Sheldon Brown, the crown seat can be milled down to proper size. However, I could never get comfortable with the idea of tearing into that beautiful clear coat, let alone riding on a reshaped fork, so this is not an option here.

Some numbers (in the "for what it's worth" column). All are millimeters.

  • 46.6 new fork's crown race seat diameter.
  • 41 old fork c.r.s.
  • 42 OD lower headtube.
  • 37.6 OD Current crown race (a 30 ID) taken off the old fork.

Looking down the head tube with the new fork slipped in. Crown race not installed but current race would have no coverage beyond the current lower headset].

enter image description here

  • 5
    I wonder if a splash of black paint will get you 80% there?
    – mattnz
    Commented Jul 28, 2019 at 6:31
  • 2
    ^ paint. And/or a rubber ring or similar to get rid of harsh 90degree corners and something more rounded instead. Or, just get over it :)
    – stijn
    Commented Jul 28, 2019 at 8:03
  • Lol. I may have to get over it. Paint is my absolute fallback.
    – Jeff
    Commented Jul 28, 2019 at 16:37
  • 3
    Tie some colorful ribbons on it. Commented Jul 28, 2019 at 17:47
  • 1
    @Criggie I focused on my mountain biking and hung the Trek road bike up on the garage rafters. Lol. I used a plastic outer ring that was part of an upper headset's top cover. I'll add an answer with pics when I get some time. The days are growing longer and that makes the bosses list longer: make hay while the sun shines, and all that.
    – Jeff
    Commented May 17, 2023 at 0:57

1 Answer 1


You are facing the as-old-as-fashion question "How can I look slimmer?", albeit on a very small scale.

Decades of empirical research and design tell us that wearing clear (possibly white) horizontal stripes color against a darker color will make the person looks like it is slimmer.

In your case, you can experiment with some matte white tape, make a ring around the fork, covering the brake mount and then paint in matte white the crown seat (the shiny, "excessive" part).

OT about the empirical knowledge on horizontal stripes: there is some peer reviewed research backing it

Thompson, P. Mikellidou, K. (2009). The 3-D Helmholtz Square illusion: more reasons to wear horizontal stripes. Journal of Vision, 9(8):50, 50a, http://journalofvision.org/9/8/50/, doi:10.1167/9.8.50

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