This map shows the seven legs of the trip:
1) Dorchester to Boston's North Station (bike)
2) Boston's North Station to Lowell's Gallagher Terminal (commuter rail)
3) Gallagher Terminal to UMass Lowell's Bellegarde Boathouse (bike)
4) Lowell to Chelmsford to Billerica to Bedford (bike)
5) Bedford to Lexington to Arlington (bike - along Minuteman Bike Trail)
6) Arlington to Cambridge (bike)
7) Cambridge to Dorchester (bike)