I have one clip-on bar where the screw was broken off. The PO, whomever that was, inserted this in the other end. I know these are a commonly used part - I received one with a front fender for my mountain bike and had to jam it up the bottom of the fork to screw on the fender mount.

Looks like a thread to screw bar end weights or mirrors into. I know my OEM Ducati bars has a similar thing.

You misunderstood me. You must be joking. 
You think I don't know how bar end weights are attached?
I know it is for the bar end weights. that's because the other end with the welded nut has a broken screw.
This was inserted into the bar end for the screw.

What is this insert called?

Oh, it's NAME?

I don't know for sure, cause it's only what I heard, but, I believe this one likes to go by the name Veronica.

Hope this helps

Michael

that looks like a tee nut as used in bed headboards the have a series of points on the other side normaly  to lock into wood (YOU MAY CALL THEM SOME THING ELSE IN AMERICA)

Nope. I know a wood T-nut.
The outer ring on this is cup shaped. You shove it in the tube and it will never pull out. Only used in round metal tubes.
This is not a trick question - I really want to know what these are called so I can order some when I need them. I don't know what to ask for or how to look it up. Someone who is a metal worker or machinist must know.

Veronica... Hehehe


Nutsert is the closest thing I can think of.... though they sit flush on the end usually -don't sit inside like that.

Quote from: adidasguy on February 05, 2012, 01:46:04 AM
Nope. I know a wood T-nut.
The outer ring on this is cup shaped. You shove it in the tube and it will never pull out. Only used in round metal tubes.
This is not a trick question - I really want to know what these are called so I can order some when I need them. I don't know what to ask for or how to look it up. Someone who is a metal worker or machinist must know.

TUBE CONNECTOR NUT

http://www.jetpress.com/Products.aspx/19072/ThreadedTubeInsertsConnectorNuts/TubeConnectorNuts/

Cookie

And we have a winner....

Quote from: adidasguy on February 04, 2012, 10:13:30 PM
You misunderstood me. You must be joking. 
You think I don't know how bar end weights are attached?
I know it is for the bar end weights. that's because the other end with the welded nut has a broken screw.
This was inserted into the bar end for the screw.

What is this insert called?

on mtn bikes = star spangled nut

on motorcycles = expanding nut (i guess)

don't buy an aluminum one, it will fatigue and dislodge at the worst possible time. everytime. buy steel. steel is real.

yeah any bike shop should have one if you go in and ask for a star nut. Bicycle forks are 1" and 1-1/8" though, so I'm not sure how close the 1" version would do on some 7/8th handlebars. The inside of a 1" bicycle for is 22.2mm, so you can measure the inside of your bars to compare, can't hurt to try it for the $2 it'll probably cost you. Any size will manage to jam into your bars, but if it's too big the flanges will bend too much and won't be able to grip anymore. I guess you could always take a dremel/angle grinder to one to make it a little smaller, if you can't find the proper size.

http://www.nashbar.com/bikes/Product_10053_10052_208247_-1___