When is a mile not a mile ?

SS - The Last Unicorn

You mean - the wheely thing wheely wasn't accurate ? Oh no!!!

Neither is measuring with bits of string (which you can't do when your markers are a dead badger and a lump of concrete - the OS don't stick essential info on their maps!) nor the miniwheely thing which MrSS got me last Christmas for measuring out the route on the map - now that really does skid bad.

Scary thought : What if scales are inaccurate to the same degree ? Maybe I'm actually 1.5 stone heavier than I thought. Yikes!!!

Pathfinder

Or 1.5stone lighter :-)

[Deleted User]

I measure my routes using my old car, new car, bike computer, OS map and finally Autoroute on the computer. They never all agree!

Mikey

I too had tried a number of techniques to measure distance: map wheel, car#1 speedo, car#1 speedo, road-bike speedo etc, and saw variations between them all.

As an unabashed techie I succumbed to buying the Timex SDM which uses GPS to record your distance / pace etc.

The results? - It doesn't agree *exactly* with any of my earlier measuring devices but it is repeatable: if I do the same course it measures the same distance.

What's more, the distances it quotes are pretty much smack in the middle of those produced by the other measuring devices. In fact, over a 5km course the largest difference I got between the GPS and the other techniques was around 1% - which was good enough for me.

The best part of getting the SDM was that I took it on vacation to Lanzarote at the end of October and used it there. It enabled me to freely explore the area whilst running and still keep track of my distance / pace figures.

Mikey

[Deleted User]

dear Santa

[Deleted User]

I've been running with a handheld GPS and have found that GPS isn't that great. The overall distance and elapsed time are reasonably accurate (say within 2%) but the speed shown jumps about a lot and you can't really have any confidence in it.

I think map measuring is the best bet if you want an accurate distance. One nice thing about a handheld GPS is that you can plug it into your computer afterwards and get a trace on a map of where you've been and get mile splits etc.

I don't think you can do that with the Timex GPS though, I use a Garmin etrex.

[Deleted User]

I know but heart rate monitor is reliable so can use that to gauge effort

Mikey

Tom,

true, the SDM doesn't have A PC interface but I only use mine for realtime indicators of pace/distance so that isn't a problem for me.

As for the speed jumping about a bit, I don't think that you can blame that on GPS itself. The SDM is more expensive than many handheld GPS devices aimed at walkers. This may be to do with the quality of its hardware and software.

If the unit knows your distance within 2% and it takes readings frequently enough, then depending upon the accuracy of your unit's timer (which should be better than .00002%) it should also know your pace to 2%.

This has been confirmed by informal tests I've done: I used mine yesterday to clock a 6 mile run. During the run, I monitored my pace continuously and it varied between 8:55 minute/mile at the beginning to 9:12 at the end (Ok, not too fast, but hey, I'm old!). As I crossed each mile, the watch beeped at me so I was able to take an extra 'control' reading. These showed the continuous pace figures to be in full agreement.

Bearing in mind my earlier post about confucious and the watches, I still feel that it's better to pick one *clock* and stick with it.

MikeB