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...in the past, I used some of those double wire baskets on the back of a 3 speed shopping bike. But it does limit you, in that you cannot easily swap them between bikes. What I do now is have the interface between the mount or rack as something permanently attached to a number of bicycles, and panniers or a front bag that easily attach and detach from those mounts. So now I can easily rotate what I ride to the store, but still take the bags with me when I leave the bike. Those double wire rear basket things are pretty practical, though. I might go back to them in the future. Mostly, people don't steal three speeds when you lock them up. Or at least they didn't used to.
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