Look at the Down Tow Up Flow half marathon from Windsor to Marlow (or the other way around). It's probably about 95% towpath with only a couple of short road/pavement sections. Fairly well organised, and a nice route along the Thames (so pretty flat).
Look at the Down Tow Up Flow half marathon from Windsor to Marlow (or the other way around). It's probably about 95% towpath with only a couple of short road/pavement sections. Fairly well organised, and a nice route along the Thames (so pretty flat).