When bike lanes are present riding on the sidewalk declines dramatically, on average ~56%, even when ridership goes up. In one case sidewalk riding went down 81% despite bike volume going up 190%.
Key quote …
“The reason that cyclists use the sidewalks is that they don’t want to die,” wrote the District’s John Glad. “If and when they are provided with dedicated bike lanes that are not accessible to drivers, they will be only too happy to use them.”