Kipchoge relies on his GPS watch for maintaing the right pace in a race

Exactly ... wrote:

GPS watches are worthless for accuracy. I used a GPS device a few years ago for my runs, only for a brief period, and found it to be totally inaccurate. My courses are well measured and I much prefer using a regular watch with split timer.

You must have s sh!tty watch.

I have a pretty basic Garmin (230) and it nails measured routes to within 1-2 meters per mile. I'm pretty neurotic about this and have run 400m tracks on exactly the right distance from the curb to test. Nails it every time.

Also, it really makes no difference if a GPS watch is 1% or more off the actual, as long as it reads this consistently. Having a consistent reference over time is all that matters.

I found my Garmin 620 to be very reliable in road races. For example, last half marathon it told me I ran 21.13km, only about 30 meters too much (and I probably didn't run perfect tangents, although I tried and should have mostly succeeded). Personally, I find it quite useful to check average lap pace between mile/km markers and adjust accordingly, especially early in a race. I also rely on it for tempo or marathon pace workouts. On the track, it makes no sense to use it though, just use your GPS watch as a stop watch and turn auto laps off.

+1

I typically wait less than 0.25 miles to start paying attention, but you definitely need to let the lap pace settle for some period.

I'm surprised how little people seem to know on this forum about basic GPS functionality and quality - at least on this thread. I thought this was settled about 5 years ago!

Jordan hssay wrote:

GPS is overrated wrote:

Umm... ever heard of lap time?

Ummm...ever heard of jordan hasay?

I think the point of this was the runner struggles to hold pace DURING the concurrent mile. Mile splits do not help for this.

Though I do agree they are over rated.

That runner needs to spend some time doing pace work in training. You CAN train yourself to hold a specific pace pretty closely. Nothing wrong with having a watch to affirm but you should not have to rely on one for every single mile you run.

scorpion_runner wrote:

My watch has been on point accurate with the gun time of every race that I have been in since using the watch. I have an EPSON Runsense SF-110. The same watch that Meb endorses, and it is known for its pinpoint accuracy. So no, gps watches are not less accurate then what people think they are.[/quote]

Is this something that depends upon the brand of GPS watch? I purchased a Garmin 220 forerunner which I was told was very popular among runners. I used it on an undulating forrest loop that I use for tempo runs. The first time it gave me 5.64 km for the loop which seemed reasonable as I would have guessed based on experience that the loop was 5.5 to 6 km in length. However the next weekend I ran exactly the same loop but in the opposite direction and the GPS watch gave me 5.25 km which is a very different reading.

I am disappointed with this accuracy but I use the GPS as a rough guide, I monitor my progress by the actual time it takes me to complete the running loops or by the time taken to do the track reps.

no they are really quite good wrote:

I have a pretty basic Garmin (230) and it nails measured routes to within 1-2 meters per mile. I'm pretty neurotic about this and have run 400m tracks on exactly the right distance from the curb to test. Nails it every time.

A track is a very, very easy test for GPS, because typically there are no obstructions nearby, and you won't be taking any sharp turns. Real world conditions are much tougher (unless you happen to live on a farm in North Dakota).

I've never had a Garmin that was consistently accurate to within 5% in cities or on trails, and I've had a lot of Garmins (including the 235, which is basically the same as the 230). Turns, tree cover, and tall buildings will all have a major effect on accuracy.

8krunner wrote:

Even Van Niekerk was wearing a GPS watch during his 400m world record.

Problem was he set the pacer function on 2:53/mile and like Kipchoge wanted to negative split. So no sub 43 ;-)

I have a garmin 60csx mounted to the handlebars of the bike which I have used to measure and certify 100's of race courses around the world (including two Olympic Marathons).

I use it to show me when I reach a km or mile point so then I could read the Jones Counter (and then I reset it after every km/mile).

What I can tell you is that the GPS could be right on or up to 0.02 miles off (32 meters). Most of the time it's within 0.00 to 0.01 (roughly 0-16 meters).

Thanks for the info Katz. I wonder what you'd get if you tested different GPS models.

In a race, or even most workouts, I don't think I'd trust the GPS "instantaneous pace" more than my gut. So the only purpose to a GPS I see is for a tempo or race somewhere you don't expect every mile to be marked. Oh, or if you don't like hitting the lap button and don't want to remember all the splits.

Forrest tempo wrote:

scorpion_runner wrote:

My watch has been on point accurate with the gun time of every race that I have been in since using the watch. I have an EPSON Runsense SF-110. The same watch that Meb endorses, and it is known for its pinpoint accuracy. So no, gps watches are not less accurate then what people think they are.

Is this something that depends upon the brand of GPS watch? I purchased a Garmin 220 forerunner which I was told was very popular among runners. I used it on an undulating forrest loop that I use for tempo runs. The first time it gave me 5.64 km for the loop which seemed reasonable as I would have guessed based on experience that the loop was 5.5 to 6 km in length. However the next weekend I ran exactly the same loop but in the opposite direction and the GPS watch gave me 5.25 km which is a very different reading.

I am disappointed with this accuracy but I use the GPS as a rough guide, I monitor my progress by the actual time it takes me to complete the running loops or by the time taken to do the track reps.[/quote]

I don't care about distance, because like the Kenyans, I run based on time, or badger miles. 18 mins=3 miles, since I run the mile in 6 mins.

My main focus is speed/pace. I want to make sure that I'm hitting my mark as exact as possible, so that I can execute my race and training strategies.