The Dutch research institute RIVM investigated the implications for public health of a substitution of short car trips by bicycle rides. The factors exercise, environment and traffic safety have been considered. The overall positive effect is a result of the new cyclists’ physical exercise. It is estimated that the so-called burden of disease has fallen by a maximum of 1.3% after one year, when everyone cycles to work one additional day a week and cycles for half an hour more. The health benefits due to less noise and air pollution by road traffic are relatively small. The effects of more exercise on health more or less outweigh the negative consequences for traffic safety caused by a transfer from car to bicycle. SWOV has calculated an increase of 4 to 8 traffic fatalities and approximately 500 serious casualties when 10% of short car trips is replaced by bicycle rides. Only for young men will this shift from car to bicycle lead to an increase in traffic safety. For all other age groups the number of serious traffic casualties is expected to rise with a transfer from car to bicycle. This increase is due to the large number of cyclists ending up in hospital as a result of one-sided cycling accidents.