A 45 tooth on a 11 tooth rear with 700c wheels would be about right for high assisted speeds with the dongle.
That would give an optimum efficiency cadence of 90 at 29.6 mph (47 kph), and few like to pedal faster than that.
The many who regard a 70 cadence as fast would only get 26.6 mph (43 kph) with that sprocket combination and 70 cadence. They'd need a huge 60 tooth chain wheel on an 11 tooth rear with 700c wheels to reach 30.7 mph (49 kph) at a 70 cadence to fully utilise the dongle's limit.
That would give an optimum efficiency cadence of 90 at 29.6 mph (47 kph), and few like to pedal faster than that.
The many who regard a 70 cadence as fast would only get 26.6 mph (43 kph) with that sprocket combination and 70 cadence. They'd need a huge 60 tooth chain wheel on an 11 tooth rear with 700c wheels to reach 30.7 mph (49 kph) at a 70 cadence to fully utilise the dongle's limit.