Boston Marathon tangents: Anyone here have it figured out?

Sara Palin wrote:

HardLoper wrote:

GPS watches are not nearly precise enough to mean anything here

Don't be a dummy. A lot of GPS watches can be within 26.3x for a marathon. Pretty much every marathon I've run has been there.

Except Boston. 26.45.

That doesn't mean the watch is accurate. Because it isn't.

Who Dat? wrote:

26.32 - I think the trick is to pick a side of the road and generally stick to it. There aren't many turns in Boston. Where people get in trouble is weaving in and out the first 4-6 miles until crowds thin out or veering back and forth from right to left at the water stations.

Thanks, weaving the first 4 miles was definitely an issue for me. I think my time will get into the first corral next year, hoping to keep the weaving to a minimum.

Tangent Overload wrote:

I think my time will get into the first corral next year, hoping to keep the weaving to a minimum.

The first corral didn't help me much. It's was still 1000 people starting exactly the same time, cramming onto the same road.

zzzz wrote:

Smoove wrote:

This guy's data suggests that the inherent inaccuracy of most watches could account for the difference between 26.2 and the 26.4 or so that most people are getting (including my 26.36).

With the 0.1 percent short course prevention factor that adds about 0.03 mile (42.195 meters) to a 26.22 marathon, the shortest anyone is going to measure with an accurate GPS on the shortest line is going to be 26.25 (26.245 rounded to the hundredth), not 26.2 miles. So you are a bit closer than you think.

Plus, if GPS watches are as wildly inaccurate as some people believe, wouldn't we see or hear of someone running 26.1x more often during a race? 26.1x should be equal to the number of 26.3x. But that's not true.

The question I should have posed in the original post is does anyone think they could shave 30-60 seconds off their race through tangents? Essentially, could you cut 200 meters off your route during the 26.2 miles?

I would say yes.

I don't know about marathons or Boston, but for a local HM on a windy course, I went over the route so many times that I had the perfect tangent line memorized on every turn. You have to pay attention the whole time, but the reduction in mileage easily came to .2 miles at least for just the HM, so I can definitely see gaining 30-90 seconds just by being ultra attentive to running tangents. I watched the people in an associated race stay in the middle of the road on a long S-curve when they should have been bouncing from side to side. Painful to watch.

I don't think anyone claimed that GPS watches are "wildly inaccurate."

As to your question of how much more efficient can tangent running be, I just did a little experiment. I took a moderately windy nearly half mile segment in my neighborhood and mapped it out on mapmyurn.com on max magnification, using the "follow the road" function. It came out at .48 miles. I then turned that function off and measured it using tangents and came out to .47, or a .01 difference. Multiply that by 52 and you can see that on a windy course, running tangents could make a pretty big difference.

Most marathon courses don't wind nearly as much, and my test was an imperfect approach because the distance involved is small and rounding could have an impact, but this is good enough for our purposes. So yes, I think tangents are meaningful, even on point-to-point marathon courses with only a few turns.

Smoove, I'm curious. I followed your Boston thread. Do you think you could have cut 200 meters (which equals 42 seconds I think in your case) if you spent more time obsessing over every wind/turn in preparation for your race?

Based on your finishing time, guessing you didn't have to weave too much in the beginning miles.

John J. Kelley did. When I ran my first Boston there were no splits or timing except for the first runner. I watched Kelley shave those corners as he ran off about half way into the race.

Rumor has it that Bill Rodgers coach...bill squires of gbtc rolled a tennis ball from hopkington to Boston to find out the slants and tangents so he could coach his runners which side of the road to run on...

I even asked him that I’m in person

He laughed his ass off that someone knew that.