So, did you mean this 1994 study, which showed riding on the sidewalk to be 80% riskier than riding on the road? Or maybe this study which found cyclists were injured 4 times more often riding on the sidewalk than on the road? Or perhaps you meant this study, which found that sidewalk riders were about 3 times more likely to be in a collision than road riders, but were 8 times more likely to suffer a major injury?

Please, enlighten us on which study you're talking about.