Since late last year I've taken up an interest in road cycling for regular exercise, and for a while I had been biking the 13 mile route from my home in Concord to my work in Newton, but the traffic along that route, especially closer to Newton, is usually heavy and rather bothersome.
To reduce my anxiety while keeping up regular cycling, I've plotted some routes around Concord that I can complete in the mornings before driving to work, and on weekends. I've two favorite loops, one from Concord to Carlisle and back, and another to Sudbury and Lincoln and back.
The Concord Carlisle route is about 13 miles and requires about 50-55 minutes, up Monument Street to Carlisle Center, and down Lowell Road. There's only one hill right around Punkatasett Hill at the start of Monument St, with a few smaller hilly sections during the remainder of the route. Monument St has many horse farms and very little traffic, and its really ideal so sometimes I just turn around in Carlisle and return the same way because I love that road. Lowell Road is somewhat busy and cars travel about 40 mph there, but there's a wide shoulder.
The Concord Subury Lincoln route doesn't have bad traffic at all, passes by the Nashawtuc Country Club, and then through Great Meadows along Lincoln Rd. The Lincoln Rd section is absolutely beautiful with very little traffic, but moderately hilly. I especially enjoy a brief stop on Sherman Bridge over the Sudbury River in the middle of Great Meadows National Wildlife Refuge. Crossing Rt 126 and turning south to pick up the other side of Lincoln Rd, the road turns to dirt for over a mile, but the wide farm fields make this segment a very bucolic ride. The loop joins traffic again in Lincoln after crossing Rt 117, past Codman Farms, and along Rt 126 past Walden Pond. This 16 mile loop requires about an hour and ten minutes.
I'd recommend a weekend ride across both loops on an early Sunday morning, for a 29 mile trek. Requiring two or two and a half hours, starting from Concord Center where you can relax at the finish with an ice cream from Bedford Farms or Brighams. If you're coming from Boston, the Fitchburg Commuter Rail line stops right in Concord Center at the Bedford Farms ice cream stand.
You can find the actual stats from my ride around the combined loop here, such as distance, time, and speed.
The roads around Concord have quite a lot of bicyclists in warm weather, and this means that the cars are generally very conscious of bikers and accommodate them well by passing in the other lane leaving a lot of room.