Route 2 to Rt 126 (Walden Street) to Concord Center, right on Main Street, left around monument and right onto Monument Street. The North Bridge Parking Area is 1/2 mile ahead on the right. The ride start is about 1 1/2 miles from the Concord commuter rail station on the Fitchburg line. Go north on Sudbury street, bear right on Main street, and from there, follow driving directions. Train schedules are here: https://mbta.com/schedules/CR-Fitchburg/timetable
A short ride for a chilly day. 29 miles from the North Bridge parking lot in Concord, north to Great Brook farm and Westford. 11:00 AM start. It's supposed to be above freezing but an insulated water bottle or a sock cover may not be a bad idea. Ride at a pace that keeps you warm and wear enough to be warm at the pace you can ride.