Review on Schwinn Bike Mirror: Handlebar Mount Accessory for Enhanced Visibility by Adrian Smart

Do not work with ergonomic flat handles. You can only tilt the mirror vertically, not at the desired horizontal angle. The round handle allows you to lean in any direction. So they are really only suitable for straight handlebars with full round grips. Also, the mirror itself is relatively small, making adjustment even more limited. If the mirror were slightly convex, you wouldn't need this fine adjustment. Remember that the mirror on a bike is more than an arm's length away, so size does matter.