I'm having trouble working out how to properly service this Shimano 105 rear hub. I've watched some videos, read Leonard Zinn's book and following Park Tools' instructions, but it doesn't help.

I've got a 15mm cone spanner around the cone (I think that's the part in the picture), but there are no flats of any size on the locknut.

I got some vise-grip pliers and managed to get it undone, but there must be an easier way!

Flats on the cone (black), but not on the locknut (silver)

1 Answer 1


OK, I eventually worked out the easier way.

The locknut has a hole in the end which, in addition to taking the skewer when fitted, has a hex socket for a 5mm allen key. Turn the hex/allen key anti-clockwise relative to the cone spanner to undo.

15mm cone spanner and 5mm hex wrench on a Shimano 105 rear hub.

  • 1
    Don't forget you can accept your own answer (since it is the correct answer)
    – Weiwen Ng
    Mar 20, 2020 at 21:22
  • 2
    A hex hidden inside a hole is not uncommon on race bike stuff - it looks sleeker and more aero than having flats on components, and flats have to be milled to look nice. A hidden hex can be cast or pressed into the component, which is easier/quicker/cheaper during manufacture. Great spotting BTW - I carry a bright torch/flashlight that is handy for these sorts of investigations
    – Criggie
    Mar 21, 2020 at 0:15
  • @WeiwenNg Thanks, it says I can do that tomorrow. I guess it can give other people a chance. :-) Mar 21, 2020 at 9:11
  • @Criggie. Thanks, interesting background info. Mar 21, 2020 at 9:11

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