yeah, they don't grow ON the pavement, but NEXT to the pavement, and if you veer off at all into a patch of dirt/weeds or take a short cut through a vacant lot you can pick them up--- I steered around a couple walking on the sidewalk, went into grass/weeds for about ten feet, and when I looked down again my tire was covered in goatheads.
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"Think of bicycles as rideable art that can just about save the world". ~Grant Petersen
Cyclists fare best when they recognize that there are times when acting vehicularly is not the best practice, and are flexible enough to do what is necessary as the situation warrants.--Me