Momentum is not the only issue. On a bicycle, when you stop, put your foot on the pavement, and start up again you are in danger. You are much more likely to have a spill and fall into traffic, and you tend to wobble starting up, especially uphill. It is safer to come to a near stop, moving just fast enough to maintain balance, and then look both ways. If a car is coming and will come through before your turn, then you should stop completely.

No bicyclist any any circumstances should "blow through" a stop sign as if it were not there. That is suicidal. A bicyclist should always stop for a red light or a pedestrian in a crosswalk.