Cycling on the sidewalk is very dangerous.
What if someone steps out of a shop in a hurry just as you pass by on your bike.
you either hit them, or swerve (into the road? into a parked car?)
Saying cyclists shouldn't be on the road, thats what side walks are for... thats just ridiculous.
A Car can do damage to a cyclist. A cyclist can do damage to a pedestrian.
There is no way to quantify the situations and say a car can do more damage. You could always come up with a hypothetical situation where a cyclist could harm a pedestrian more than a car... that argument is illogical.
Cyclists are killed each and every year by car doors (from parked cars). This would be no different if you were cycling on the sidewalk (shop doors). Most sidewalks are not big enough to accommodate both pedestrian traffic and bike traffic.
If you say there's too big of a mismatch between cycling speed and car speed so bikes should not be on the road, then how can you say they should be on the side walk. Now you have a gross mismatch between cycling speed and pedestrian speed.
When I bike to work, I am not crawling at 4mph... A road bike with semislick or slick tires generally goes 15-25 mph. [depending on the cyclist, fitness, road material, hill / no hill etc]
so what happens when a cyclist moves to the sidewalk then? I can no longer safely bike at 20mph on the sidewalk because that could cause serious harm to a pedestrian, myself, and my bike! Then there's also all sorts of delays, you can't just cycle across an intersection on sidewalk with out stopping and looking... if you are in the road [and following traffic law] then the lights guide you. On the side walk a car driving down a side street might not see you coming as his eyes are on the road ahead and the traffic lights/signs not the perpendicular sidewalk. So chances of crashing while crossing side streets go up drastically.
long story short. Bikes belong in the road. They share equal traffic responsibility with cars. Make more bike lanes! Add new types of traffic lights for cyclists (check out the portland / seattle area). I encourage you to be angry when bikes don't follow traffic laws just as you would when another car doesn't follow a traffic law.
If a cyclist is hit by a car while he blows through a stop sign that is the cyclists fault. If a car plows down 8 cyclists while trying to pass another car, that is the drivers fault.