Don't use the 'open road' to assess your speed.
It is called the 'open road' because it is open to all roadusers.
You will start to take risks to beat your PB.
Owners of Garmin Edge or eTrex are able to analyse their data to sort out the 'flat road speed' >10 mph.
It doesn't matter what traffic or stops you encounter, the result will be a figure for your 'cruising' speed on gradients <2%, >-2%.
Criteria of >10 mph, +/- 2% are what I've found to give the most representative result.
Not surprisingly, the resultant 'flat road speed' gets lower as the ride gets longer,,,
It is called the 'open road' because it is open to all roadusers.
You will start to take risks to beat your PB.
Owners of Garmin Edge or eTrex are able to analyse their data to sort out the 'flat road speed' >10 mph.
It doesn't matter what traffic or stops you encounter, the result will be a figure for your 'cruising' speed on gradients <2%, >-2%.
Criteria of >10 mph, +/- 2% are what I've found to give the most representative result.
Not surprisingly, the resultant 'flat road speed' gets lower as the ride gets longer,,,