This is an old back hub that has back-pedal break, and two internal gears. As pictured it has two slitted nuts that lock the hub.

Which tool should I use to remove these nuts without damaging them?

Is there some way of removing them without a special tool?

Rear hub with flat slitted nut Rear hub with flat slitted nut

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    You need what is called, in the US, a "spanner". (In the UK "spanner" == "wrench", so there's presumably a different term there.) There are different styles -- what Petaspeed illustrates is one style, others have pins but will also work. In a pinch you can use a cold chisel and hammer. – Daniel R Hicks Aug 8 '16 at 16:36
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    This is one commercially-available version, though I don't know if it's the right size: amazon.com/Park-Tool-HCW-5-Lock-Spanner/dp/B000C17KRI/… – Daniel R Hicks Aug 8 '16 at 16:36
  • The HCW-5 is a 40 or 42mm wrench. It's used for freewheels. The nut above looks to be 20-25mm (based on axle). – DWGKNZ Aug 11 '16 at 2:30
  1. The correct tool is called a collet/slotted nut wrench/spanner (regional variation on names). I've not seen a cycle tool company version that small but you can buy them online in both a fixed and adjustable width.

Adjustable Wrench

  1. As suggested above you can fashion a tool or use a hammer and screwdriver/ punch to loosen the nut.
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  • Saying "use a tool like this"... "I have never seen a tool like this small enough to work", doesn't make sense to me. – Nuі Aug 11 '16 at 22:58
  • I haven't said that. I've said use a slotted nut wrench, but not one made by a cycle tool company (park tools, union, X tools, pedros etc) because their smallest is generally 40mm and too big for those nuts which look to be 25mm) – DWGKNZ Aug 13 '16 at 6:00

With an angle grinder and a flat file you can easily make a tool for this purpose from flat iron (preferably hardened):

Home made tool for flat slitted bolts

If you use hardened flat iron, make sure to spray or dip it in water regularly too not lose the tempering when grinding. The small tip that fits into the slit of the nut needs to be finished with the flat file since the angle grinder doesn't reach to make it the right angle.

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You need a pin spanner, regional wording may vary.


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  • A pin spanner wouldn't work on this, they're for use when there are two holes on the face. The pins wouldn't sit right in the slots and not offer adequate leverage. – DWGKNZ Aug 10 '16 at 20:14

Some people use a screwdriver and a hammer, tapping the nut in the direction you want to go.

I personally have not done that, and I don't recommend it. But some people do this, and it seems to work for them. Not ideal, but could get you out of a bind if you have limited $ at the moment.

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  • A punch works well. It's generally considered a destructive method and not recommended. – DWGKNZ Aug 10 '16 at 20:09

How about using a file to file some flat surfaces onto the nut, so that it then takes an ordinary wrench for hex nuts?

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