Started out with plan for 3 CCWs and home, then back for 2 CCWs. But I didn't want to face the climb to Rt 2 twice. So I started on 1 CCW, but never completed it and looked for flat in Bedford since Carlisle was cold. Flat turned out to be Old Bedford Rd in Concord and Rt 62 in Bedford to McMahon Rd to Bikeway Source - avoiding the climb to St Michael Catholic Church. I did variations on that for 5-6 times (about 4 miles each way) to about 80 miles. At around Noon I went to New London for a Bacon-Turkey Wrap+Pepsi and then returned to the "Flat 4 milers" Then for the final 20 miles I went to Concord Center and out to the 5 mile mark (Bingham Rd) on Lowell Road and back to Concord Center for my only climb to Rt 2. That was going to leave me short so I took Codman Rd to Old Subury Rd/Waltham Rd for 2 laps and home. I was still a little short of 102ish so added a little going to the end of Farrar Village and then home. Turns out it may not have been so flat - about 3000' of elevation - but no school busses to have wait while they dropped off kids and home before dark. HR, speed and Cadence were pretty uniform and high until mile 85 or so (14.4 mph) then plummeted into the 12.5 mph range.