I´m training for marathons and apart from running 4-5 times a week also cycle to work 5 times a week. It´s 9 miles each way with varying speed (due to city traffic and terrain - some in heavy traffic, some through Richmond Park where I can go much faster). It normally takes me 30-35 mins. How much of it can I count as part of my weekly mileage for running? I.e. If I aim to run 50 miles a week, can I take 10 miles or so for my cycling?