It’s outdoors so potentially more interesting than being indoors in the pool/gym. Also, the roads around Cambridge tend to be flat and quiet. It’s a good way of transitioning from swimming pool cross-training to running when you’re recovering from injury, and is a good way of adding to your training load on top running you’re already doing with less of an injury risk than more running miles.
The busway north of Cambridge is a pretty good starting point if you’re not sure where to go, while the cycling club have some example routes here.
If you’re looking to add volume to running then a good place to start is something like two 90mins cycle a week, measuring your effort either by speed or by using a power meter. There are quite a few Hareys who use cycling to add onto their training, so get involved with a group ride (or with the triathlon/cycling clubs).
Cycling still involves bearing 20-30 per cent of your body weight, so if you’ve got a serious injury some time in the pool might be more appropriate – check with your physio.