I have a large front rack that is 17 inches wide. Is it possible to attach bike mirrors to the back side of the rack that extends to the right and left of the bike?
4As a general rule, the farther the mirror is from your head, the less effective it is.– Daniel R HicksOct 17, 2018 at 16:29
Why would you want them on the rack, rather than the handlebars? Moving the mirror farther away means that it's a smaller fraction of your field of view, so you can see less in it. Also, slight movements of your head will move the view in the mirror more, which also makes it harder to see what's going on.– David RicherbyOct 18, 2018 at 9:13
It's certainly possible. It could well be easy, but on the other hand you may have to modify parts quite heavily. There are decent quality mirrors designed to clamp onto handlebars and extend past your arms. I'm most familiar with the Busch und Muller cyclestar because I use a similar mirror with a different attachment. Cheap mirrors tend to wobble about and be useless, but there are plenty of decent brands (mostly European).
If the tube diameter is similar to the diameter of typical handlebars, you may be able to use the clamp almost as designed. If not, you'll need to make some adaptations, such as packing out the clamp.