I got it for Christmas.

Best present ever.

It rules.

12/27/2007 10:35:05 AM

I want one for my mountain/road bikes.

I just cant justify the price tag.....although I DID get a few gift certificates for xmas....

12/27/2007 10:38:00 AM

I picked up the 305 this past March. With rebates and sales I think I got it for $205. It's a pretty sweet toy for sure.

^ If you are getting one exclusively for biking, have a look at the edge 305, not the forerunner. I just now (literally, 3 seconds ago) had a look at the edge specs, and what I had suspected all along was verified. It includes a barometric altimeter which is actually a ton more accurate for measuring elevation change than GPS. If you go with the forerunner (which doesn't have a barometer), there are ways to correct the elevation measurement by using topo maps, and garmins own web based training tracker, motionbased.com, can do this automatically for you. With mountain biking though, the samples are spaced far enough apart that it is going to miss a lot of the elveation if you are going down then up quick enough. Think, flying own a hill at 30mph, and shooting up the other side, it could miss say 20-30ft going down and up, and if you do this enough during your mtb'ing, you won't have the best record of just how much climbing you did.

I picked up the forerunner instead of the edge because I am (was ) doing a good bit of running, and I like to be able to wear the in-run stats on my arm to keep track of the heart rate, pace, distance.

It's a very slick little toy for sure.

12/27/2007 11:09:34 AM

Quote :

"It includes a barometric altimeter which is actually a ton more accurate for measuring elevation change than GPS."

Really? Even with weather changes in barometric pressure? Damn, GPS is pretty shitty at elevation estimation then.

I guess weather/temperature variation is only a problem when you end up with a rapid change during the day though. Still kind of impressive how much more accurate it is (I've been looking it up.) Sounds like it would still lose meaning if a storm front approached though. But yeah assuming relatively stable weather during a day, it looks like barometric altimeters are the thing you want for relative elevation calculation- and the high end garmins can use the GPS and maps to calibrate or so the reviews say.


[Edited on December 27, 2007 at 11:35 AM. Reason : ]

12/27/2007 11:28:41 AM

I'm not a GPS expert, but the motionbased site has a link somewhere discussing the elevation error with GPS being like 10x worse than horizontal. I can attest to this while standing still, my Forerunner will oscillate 100ft worth of elevation.

In regards to barometric pressure, I'm no expert there either, but my gut sorta scientific instinct says a couple of things in regards to why this is a really accurate measurement for biking

1. The pressure change with height can be measured with high resolution, meaning, the tool must be able to detect changes in feet pretty easily
2. The pressure change with weather is small compared to the change with height
2a. The pressure change due to weather is slow compare to the change in height.

Someone else educate us in these regards.

12/27/2007 11:56:47 AM

all i really need is how far I've gone and how long it took me to get there

but the addition of seeing where I've run on Google Earth is pretty kick ass

12/27/2007 11:59:43 AM

305 FTW

12/27/2007 1:17:25 PM

Quote :

" 1. The pressure change with height can be measured with high resolution, meaning, the tool must be able to detect changes in feet pretty easily 2. The pressure change with weather is small compared to the change with height 2a. The pressure change due to weather is slow compare to the change in height. "

Yeah it works out that although mathematically the effects of elevation above sea level and temperature on the expected pressure are both of the same order and exponential- your altitude above sea level is going to be between -5 and 8850 meters (everest) while the local temperature hopefully should be within 260 and 320 kelvin. So yeah, on earth temperature isn't going to make a huge difference.

Weather effects are a little more severe though. A change in 150 pascals (just about twice the minimum where fish will notice and about 1/50th the dip is considered "extreme" for the US and 1/100th the record drop recorded during a typhoon) would have you thinking you were about 50 meters higher than you might have expected. That's how much a fast moving storm is likely to change the barometric pressure in an hour.

So yeah, if your forerunner is oscillating 100 ft while you're looking at it, a 50 ft shift in an hour is great by comparison.

[Edited on December 27, 2007 at 4:25 PM. Reason : ]

12/27/2007 4:24:10 PM