How do I get this out?
 

I was playing around with my stem and spacers trying to make some reach adjustments and being a bit overzealous I may have forgotten to grease a bolt or two...

Now I'm stuck with the unfortunate situation below. My 4mm allen screw (above the stem cap) is stuck in the thingamajigger below the stem cap, so whenever I turn the allen screw the entire thing turns, thus not allowing me to unscrew and remove the stem cap. It also won't tighten my headset when I drop it in my steerer tube. Help!



http://i.imgur.com/yU6yLW3l.jpg

Simple solution is to just replace the compression plug. And grease it this time. Andy.

There are two ways to get a grip on the outer bolt.

You can buy a pair of nuts and thread them on jammed against each other like a cone and locknut. Then hold the nut that would turn against it's mate with and remove the bolt with an allen key. Or you can buy a single nut, saw through one side and thread it on, Place in a vice, or use a vise-grip, in a way that squeezes the nut against the bolt, then remove the bolt.

But before doing this, soak it all in penetrating oil, and if the bolt resists, try working it back and forth in small arcs taking what it gives you, and incrementally gaining more working room. Otherwise, you can make it worse, as the small shards of galled metal roll and get bigger tearing up more thread as they go.

Putting the bolt into a vise with a piece of thick leather (old belt) wrapped around it should hold it securely enough.

Or grab the bolt with a machinist's collet.

got an axle holder, that goes in your bench vise?