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This nut (pictured) fits the binder bolt from a vintage 3ttt stem. I would like to know the name of this nut, or the type of nut this is so that I can try to buy more.

stem binder bolt nut bottom stem binder bolt nut top

So far, I've found similar things when searching the internet with keywords like "knurled", "conical", and "tapered", but haven't managed to find anything that has the flange.

Can anyone help?

Edit: For clarification, here's a pic of the nut in situ

3ttt stem

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    I've never seen anything like it on a bike. Where exactly is it positioned?
    – Daniel R Hicks
    Commented Apr 8, 2018 at 0:42
  • I'd say a proprietary nut used by TTT. Most stems of that type used standard six-sided (lock) nuts in a six-sided recess. You could be lucky on a vintage parts market.
    – Carel
    Commented Apr 8, 2018 at 7:59
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    Just out of curiosity, what's wrong with the nut? (Or do you need a matching one for a different bike?)
    – Daniel R Hicks
    Commented Apr 8, 2018 at 12:39
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    Did you ever find these? I have the same stem and looking for a replacement too (I snapped the bolt and managed to find a replacement at a local bike coop).
    – Josh
    Commented Feb 18 at 14:22
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    @Criggie As I tightened the stem clamp bolt, the stem clamp binder nut completely dug into the stem, bedding itself in there nicely. It felt odd to do, because it is a slightly destructive process. I never would have expected the stem to deform enough to accommodate the size of binder nut I had — but...it did. After all that though, the stem was too short for me lol
    – Paul Roper
    Commented Feb 29 at 2:37

4 Answers 4

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It's called a stem clamp binder nut. The names don't get more specific than that, unfortunately. You could search for the bolt by the stem name, and maybe get lucky finding another one. It's not a super-common setup for stems; they typically used a hex nut.

If it doesn't fit a little further into the stem, it's most likely an incorrect size for the stem. The flange should sit flush when the bolt is fully tightened. The binder bolt thread only comes in a few sizes, so you may just have a bolt that "works" but is not original to the stem.

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I've found something similar (only the other way round) for Cinelli: https://www.ebay.com/itm/Cinelli-1A-stem-clamp-serrated-section-fixing-bolt-and-nut/142719429884 and I was searching for "stem clamp serrated nut". This one has the flange.

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Maybe something like a "Countersunk External Serrated Tooth Lock Washers" Countersunk External Serrated Tooth Lock Washers in combination with a lock nut turned upside-down "Hex All Metal Lock Nuts" Hex All Metal Lock Nuts

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As JonR said back in 2018 it is called a stem clamp binder nut. That would be the generic name for any nut used in this context - a handlebar stem.

It can also be called a knurled spline nut or just a spline nut.
enter image description here
The length and diameter are variable parameters.

Don't confuse these with rivet nuts.
Article on rivet nuts and how they are installed.

If it were me, I'd just find a longer bolt and use a regular nut on the back.

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