The Pedestrian and Bicycle Information Center in the U.S. has a Bikeability Checklist that may also be helpful for your route planning.
Best route planning along with bicycle skills and safety education is key for children riding bicycles.
Review the information on Developing Best Walking School Bus Routes. The bicycle route planning process requires a similar approach, though it has its own considerations as well. BIcycle Train routes must take into account on-road traffic conditions and access to local shared use pathways or trails. Sidewalks must never be used for a Bicycle Train route. If the Bicycle Train leader, or student participants are not confident enough to ride on the road, then this is not the appropriate strategy for their safe and active journey to school. Developing competent cyclists in your school community may require a plan for bicycle skills and safety training. Consider establishing a bicycle safety education program at your school to ensure that families who wish to organize a Bicycle Train can be confident that parents and children have the skills to participate.
Once you have finalized your decision, identify the route on a map and make copies for all families involved in the Bicycle Train, so that everyone is familiar with the route that the group will take to and from school.