The only way to find out anything is gather hard data. If that doesn't work, submit your question to the '41, throwing in bits about tires, air density, and average speed. Just kidding. :-)
Measure the time moving vs the time not moving would be the first and easiest test. Use 2 different pieces of equipment and methods, maybe 3. Might go like this:
Total moving time measurement: Regular bike computer with autostop.
Non-moving time measurement: get a cheap stopwatch on your bars or wrist for every time you are stopped in traffic, collecting the total time stopped.
Lap times or segment times: Use your smartphone with an app like Endomondo, Strava, etc that records lap times along with a mapped chart showing your speeds, also with autostop.
Now you have 3 different pieces of data, from 3 different devices, and there should be a strong correlation between the data. Do this for a week so you can get 5 points / 5 runs. Now you have total ride time (measured), total non-moving time (measured and calculated), lap times, and speed / time charts from your app.
Actually, I'm really curious how this works out. Love to see the results.
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Last edited by RoadTire; 10-09-14 at 08:10 AM.