I like having a mirror and have tried all kinds. On one bike with 105 I used a miricycle hood mount and liked it. I haven't found anything similar for my SRAM Force hoods or would try it. Glasses mounted mirrors just don't feel comfortable to me although others love them. A friend hand makes helmet mounts from old bike spokes and hand cut and smoothed mirror fragments (the nipple is soldered onto the mirror which screws onto the spoke tip). I mounted one of his mirrors on my helmet a couple of years ago and love it. A nice feature is that if I have my helmet I have a consistent experience regardless what bike I ride.