My wife's touring bike has Ergon grips and a MirrorCylce mirror that I was able to attach to the Ergon. Replacing with Ergon cork?? But the interior structure will not support the long bolt set up.
So here is my idea. I will epoxy a wooden plug inside the handle bar and then drill and install a threaded insert.
Thoughts?

OK report back with your results..

epoxy may be overkill.. irreversible after it cures ..

Sounds reasonable enough, though I'd probably use hot melt glue vs. epoxy. You may be able to do it yet more simply by modifying an old fashioned expanding bar plug.

Yes,epoxy may be overkill but if it did not work it along with the plug could be drilled out.
FB, not familiar with an expanding plug.



TE=FBinNY;19402324]Sounds reasonable enough, though I'd probably use hot melt glue vs. epoxy. You may be able to do it yet more simply by modifying an old fashioned expanding bar plug.[/QUOTE]

If you are going to use epoxy anyway, which is pretty permanent,you could skip the wooden plug and just epoxy a threaded insert in the bar. I did exactly that on a bullhorn bar, also to mount a Mirrycle mirror, and it worked just fine.
The insert had a 3/8" minor diameter, so I had to drill the mirror mount arm out to accept a 3/8 screw, but that was no problem.
EDIT: Now that I'm thinking about it, I don't remember for sure if it was 3/8, 5/16 or 1/4. I don't have the bike here at the moment to check.

putting a screw in you can use a rubber plug, Its how Velox bar plugs work .
the nut *, on the end of the bolt, inside, and a flat washer on either end of the rubber plug
tightening the machine screw, causes the rubber to expand, compression.. to fill the tube ID.

* I like T nuts, (woodworking dept) since they're threaded and have spikes to dig in.

trouble with Velox bar plugs, in practical long term , is the nut rusts, then they're hard to unscrew as it just spins on the bolt.

share a nice bottle of wine with the wife, and then use the cork.



....

I don't understand your difficulty. I have two bikes with Ergon cork grips and Mirrycle mirrors; I do not recall having trouble mounting them. The Mirrycle kit has two different-sized wedges and the small ones fit fine IIRC.

dsbrantjr,
You know I think your idea would work! I will give it a try.

I'm a bit confused here; I have Ergons with a mirror, and it's the mirror expander goes into the handlebar, the grips are irrelevant; just pop off the end cap and insert. What am I missing?

I originally had a Mirrcycle mirror, and found my arm blocked it in any position I could come up with (down and inside worked, but I couldn't see anything that way...). I ended up with a Third Eye mirror instead (goes straight out horizontally, mirror very close to grip), that seems to work better.

I use a Take-A-Look mirror mounted on my eyeglasses