"While Grantchester is well-known, Coton is not - there is a reason"
Start at The Backs. 4 to 5 miles return
The Coton cycle path is all tarred, fenced, and not very exciting. The footpath is a challenge every time.
The combination of route along the Wimpole Way and back to the Rugby Ground makes a very enjoyable round trip (when ignoring the motorway). Furthermore, there are a lot more alternatives for very long distance runs.
There are three main routes to Coton:
Past the University Library and Robinson College towards the new Athletics Ground. On the cycle path past the Cavendish Laboratory to Coton.
Alternatively, from the University Rugby Ground on Grange Road, there is a seasonal footpath to the footbridge crossing the motorway - try finding it in winter when there is no high grass (actually, it is easier to find when you come the other way; at the motorway birdge, follow the track through the little wood).
On Barton Road, at the outskirts of Cambridge, about 200 yards after Queens' sport ground, there is a public footpath (on the right). Passing over fields, a bridge, and beautiful meadows, you get directed to Coton - just follow the yellow arrows (not suitable for people with weak ankles!).
From the Coton Primary School, there is a footpath to the American Cemetery on Madingley Hill. The sight from the hill is worth at least one trip - weather permitting.
The footpath continues at the west end of the cemetery leading to open farmland. In order to get to Girton College, keep going along the the path cutting through the fields but do not cross over the bridge over the A428; instead, turn right about 200 yards before the bridge and follow that path to a subway under the M11. From there, it's straightforward, however, it is also tarred and will stay that way even if you head towards the University Farms and the Royal Greenwich Observatory (round trip 9-10 miles).
In the unlikely case of the military not conducting any shoot-to-kill excercises on their rifle range (watch out for a red flag on the hill south of Coton - you go on at your own risk), it is possible to continue on the Wimpole Way on the other side of Coton. In Coton, go westwards past the church and the primary school and follow the road to its end; the footpath continues there.
The author cannot be held responsible for any kind of injuries, trespassing violations, or anything else occurring in connection with following the stated routes. Anyone may do so only on their own risk.