VT to CA

My Edge 205 is screwy. I average 25-29 on the flats, this is verified by Powertap and my old Polar... Garmin gets these figures as well. Garmin also matches up with established climbing averages for specific hills...

Here's where it gets weird.

My fastest descent speed reached as recorded by Garmin? 31 mph. Average descent speed is 27. These numbers are wildly different than those of the Powertap and the Polar... in fact the other day descending Mulholland towards Caheunga, I was right next to a Vette, and had a clear view of the dashboard, including the large digital speedometer (total "Gleaming The Cube" moment). The Vette's speedo read 47. The Garmin was recording 30 even.

What the hell is going on? Anyone else experience this?

G_Sup

Something's screwy. No, I don't experience that at all, but then again I have the 305.

reef58

Could be the massive amount of power you are putting out is causing electrical interference with the Garmins signal.

On a serious note if you are in the mountains, or in heavy tree cover that may interfer with the signal. Ohterwise the speed from GPS is usually pretty accurate, but I can't verify that particular model.

I suggest more concentration on 47mph descents, but that's just me.

Richard

VT to CA

Exactly what runs through my head on every descent lately... "I must be doing 40... 45... don't look down. Don't look at the display, concentrate on the road..."

I need to solve this problem before I end up flying off a cliff side. I can picture it now- pop over the low curb alongside one the of the no-guard-rail sections... and as I'm descending into the San Fernando Valley the hard way, mid free-fall I glance down at the display... 23 mph. "That can't be righ-" Splat.

BetweenRides

Just a theory, but it could be due to the fact that the Edge calculates speed via gps on linear distance. When you are going down a slope, you are traveling down as well as forward, so the perceived linear distance is less.

Not sure if that covers the amount of error you are getting, but it makes sense to my twisted way of thinking! And if its true, the Garmin has a built in error that I hadn't thought about. Pretty flat where I live, so it would be hard to test it against a regular cycling computer. Have you tried running the Edge and a cyclocomputer together on a hilly course to see if there is a difference?

JayC

Does it get fixed when you upload the ride to Motionbased? My average always goes up a little when Motionbased corrects GPS errors.

gpelpel

My Edge 305 speed reading is consistant with my Polar 725 even on descent.

GPB

Yeah...that's the first thing I thought of too. Since GPS accuracy is extreme in 2-D but not so good in 3-D (elevation)...I bet that probably accounts for a bunch of the problem. Steeper the hill, the slower you go. Fall off a cliff in "freefall"...it would show zero MPH??? Seems this situation would be too common to not be documented somewhere.

cgallagh

My 205 is accurate and compares to cyclocomputers on at least 3 other bikes, climbing, flats, and descending. Don't know what the problem is. I do have a problem with my HRM sometimes going crazy when the GPS is on. One day it said my HR was 285 bpm. I had to make sure I wasn't dead.

dantr0n

I can't believe you used the phrase "Gleaming the Cube", now I'm going to have go watch it and waste a couple hours of my life.