It is repeatedly obvious that I am not safe from my curse, no matter what my form of transportation. If I am driving, I get stopped by that infernal light. If I bike, I get stopped by that infernal light. If I run, I get stopped by that infernal light. Thank goodness they haven't installed one in the pool just yet.
In a previous post, I postulated that, for each stop light encountered, I lose 0.1 mph from my average bike speed. Is this true? Before, it was just an educated guess. As a teacher, I've got a little more time on my hands. I love summer. So I do what all the other teachers are doing with their new-found freedom: Newtonian Physics. Let's see how the math works out in a hypothetical ride, then in my 13, 25, and 40 mile courses...
-The cyclist consistently maintains 20 mph (roughly 32.2 km/h) sans stop lights
-Stopping and starting distance will be 40 meters
-Upon stopping, time will magically stop (not penalizing you for how long you wait)
Scenario 1- Ten mile ride
Ten miles is roughly 16.1 km or 16,100 meters. Sorry for the metric, it just helps out when doing the math. The formulas are much easier using SI versus the customary system. During this ride, let's scatter 1 light every 2 miles for a total of 4 lights (#1 at the 2 mile, #2 at the 4 mile, #3 at the 6 mile, and #4 at the 8 mile. No need for #5 as you are back home).
If there are no lights, this ride takes 30 minutes. A cyclist covers 80 meters in about 9 seconds. Not bad. Things change when you add in the evil. That same 80 meters, when you slow down, stop, and speed back up takes 18 seconds. This represents an increase of 9 seconds for the same distance. Over the course of a 10 mile ride, including 4 lights, your time changes from 30 minutes to 30.36. Low and behold, the new average speed 19.6 mph. So those stupid stoplights, over the course of a short ride, dropped the average speed by 0.1 mph per light. I love validating hypotheses.
Scenario 2- My 13 mile course
I, like most of us, have a few select routes to which we will gravitate. I have a 13 mile course, 25 mile course, and a 40 mile course. I can add distance with tiny out and backs or loops. I use my 13 mile ride for recovery or sprint distance-specific training. It has 14 stoplights. Let's assume that 50% of the lights are red (very light assumption here, I bet the number is closer to 80% but I refuse to do that data). This means I tack on 7x9 seconds or 63 seconds. In 13 miles at constant velocity, I should cover the distance in 39 minutes. Add in the hell, I increase to just over 40 minutes. My stoplight pace is now 19.5 mph.
Scenario 3- My 25 mile course
On my medium-hard ride, I have a nice loop. This route has it all. It's got big hills, little hills, rolling hills, and flats. Whatever skill I want to work on that day, it's got it. But, you have to take the good with the bad. It's also got 18 lights. Using a 50% success rate (which is wholly inaccurate for this stretch), my should be 1 hour 15 minute ride mystically extends itself to 1 hour 16 minutes and 21 seconds. The pace is 19.6. Just for giggles, I calculated out the pace for hitting every light on the course (not realistic but closer than 50%). My new pace drops to 19.3.
Scenario 4- My 40 mile course
When I start getting into the distance stuff, I hit my tempo rides on a different course. This route has a frustrating 7 miles of hell, 2 miles of purgatory, and 22 miles of cycling heaven. The total light count is 36 lights. Forty miles should take 2 hours. At my modest (yet never achieved) 50% green light, my pace drops to 19.6 mph. At full 100%, the new output is a whopping 19.1.
So there you have it. Stop lights suck. They sap the life right out of the session. At 9 seconds per light, they could make or break a good ride. The loss of 0.1 mph/ light may be misleading depending on the concentration and success rate of scoring the intersection.
Oddly, I tend to get over grumpy with red-light blues. They bring me down, boil the blood, and anger the soul. Now, I know exactly what they take away from my workout. Yet, I do not experience the same emotions towards the stop sign. Mainly because I feel the octagon is an equal opportunity usurper. All must stop. The red light, in its masochistic mindset, is singularly focused on taking me out of business. I hate you stop light.