Hi Freewheeler
I have just gone thru the search for a mirror for use with my Trekking bars. I looked high and low (in LBS and online). The best so far that I have found are these two velcro strap-on mirrors. The best one is sold by Mountain Equipment Co-op
http://www.mec.ca/Products/product_d...=1237731253386
The other one is a Blackburn model that I picked up at a local Toronto LBS but is available from Nashbar as well.
http://www.nashbar.com/bikes/Product..._200322_200438
These two mirrors both velcro-strap on in a similar area in the front corner of the left bar loop. The idea is that they still allow me to use the front of the loops as a low aerobar position and yet still give enough clearance for my hands at the outside back corners ( as with bar-ends)
The MEC one has a slightly longer shaft and allows a little more clearance as described above. It also has a better angle locking mechanism for the mirror itself. The shaft is metal, which is, I suspect a much better longterm durability issue.
The Blackburn mirror has a better optical mirror surface but it doesn't extend out far enough to clear your hands on the outer part of the bar. The shaft and ball joint is also plastic which I'm sure will not stand up long term. It is also much more difficult to tighten the ball joint adequately to avoid vibration movement.
The MEC mirror is so incredibly cheap that I can easily put up with a slightly less optically-pure image and I can afford to carry a second one with me as a spare. Actually I'm considering using two of them together to extend the shaft about an inch ( cutting the shafts and bolting the two together adding some length). This sort of thing would not be possible with the Blackburn model.
Incidently, when I'm not on the bike I use a discarded earmuff cover to protect the mirror.
I used a couple of small pieces of stick-on foam padding that came with the Bontrager handlebar wrap kit to tighten up the metal cup mount on the wrapped bar. It is now tight enough that it doesn't vibrate loose no matter how rough the road nor does it bump out of position easily.
The big advantage of the velcro wrap attachment is that it can be dismounted in a flash for clearance and it's no-big-deal to re-attach it.
Doug