Originally Posted by
shovelhd
There is no rule that I am aware of, only that your bar end must be plugged. However as I have explained in the past, if a referee feels that it gives the rider an unfair advantage or is a safety issue, they can ask that it be removed.
I have a similar mirror on both of my bikes now, an Italian one that has a glass lens. It goes under the bar tape though so it's not removable. It's been a game changer for me with my vision issues. It makes road riding, especially in a pace line, much safer.
I 'm glad that helps you. I saw the model you had and selected this slightly heavier one as it does unplug and adjust. Junior can cover both sides with one mirror - leaving the other bar available for a bell :-)
Off topic rules, touchy feeling stuff:
I think but the "unfair advantage" is one that I have never seen enforced properly in cycling (or soccer). There may be an advantage, but it is not unfair if others have the same opportunity to legally use it. If they didn't know about it, or chose not to use it, or couldn't afford it, it does not become unfair, from a cycling rules perspective. I see affordability as an issue, just not for referees to deal with.
This is a @20 mirror.