I went out for a ride to get a feel for how the range varies with road and riding style. I fully charged at the Tesco Extra chargers, then headed cross country via Bridgnorth towards Stourbridge and Hagley to the M5. That's a mix of fast A road and stop/start urban roads, with an overall average speed around 30mph. The dash reported an average consumption of 120 Wh/mi (8.3 mi/kWh) which would be a range of 100 miles. I then headed out on the motorway with the cruise control set to 75mph, but the bike's speedo reporting 73mph, and my phone's GPS saying 70mph. The dash now calculating a consumption of 180 Wh/mi (5.5 mi/kWh) which would be a range of 65 miles. I guess that gives me the kind of spread of consumption I can expect to get, which I can factor in with route planning.
