I fit bar end mirrors to all of my bikes because I'm now too old and too fat to twist round as easily as I used too.
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I've tried many "cycle" supplier mirrors and found them either to be very expensive or fragile, or both.
I then bought a pair of very cheap motorcycle bar end mirrors via ebay, and they've proved to be the best solution for me. Sturdy but very light and small, cheap, no plastic, and versatile mounting.
I've now got one fitted on the right side of all my bikes. Best of all, they're very cheap, less than £10 a pair, delivered from UK sellers. Even though they're "handed" left and right, I found that I can use them either way round, so one pair serves two bikes, both on the right.
The mounting has two options, either an expanding alloy
insert, or that can be removed and the clamp fits
over the last 12mm of bar.
This photo shows them on some of my bikes, including the Trance, which has upright bar ends clamped on as well.
There's loads of ebay sellers for them, like this UK one, or you can buy via china for a few quid less, but then face a three week wait. (This one even does "click and collect" via an argos store).
http://www.ebay.co.uk/itm/BIKINGEAR-BLACK-MOTORCYCLE-BIKE-BAR-END-MOUNT-ALLOY-MIRRORS-PAIR-22mm-7-8-BARS-/271555116450?pt=UK_Motorcycle_Parts_13&hash=item3f39f23da2