Garmin Edge 500

Headhuunter

The last couple of times I've been out for a ride I've noticed that my Edge 500 has begun to show that I am moving when I'm stationary. I have literally stopped and leaned the bike up against a tree. The bike is at a full stop and the Garmin goes into auto pause. However whilst I'm having a break it starts to register that I am moving at anything between 1 and 2mph which then brings it off auto pause and it starts destroying my average speed!

Why is it doing this? I haven't noticed until the last couple of rides. Does the cold affect it somehow? I know that GPS registered speed is not meant to be that accurate but I haven't had a problem til now... Has anyone else experienced this?

dhope

Sometimes with my 800 it happens, which is odd given that I've got the speed/cadence sensor too so it knows the wheels aren't moving.

So you're saying that's the only reason my average speed isn't up there with JZed? Interesting...

rolf_f

It knows your location based on the satellite fix which has a certain margin of error associated with it. Probably you haven't got that strong a signal (crappy weather has an effect) and so the registered movement is just noise.

You'd have to be doing very short rides with very long breaks for it to affect your average speed stats though I would have thought. A few seconds at 2mph as against a few hours at 15mph? Next time it happens leave the display on so that you can see your average speed and wait for it to drop 0.1mph. You'll probably still be waiting at Christmas

Pufftmw

You can also get building reflection in built up areas and small movements in speed are likely to be the unit correcting the fix compared to last known location.

Headhuunter

Rolf F wrote:

It knows your location based on the satellite fix which has a certain margin of error associated with it. Probably you haven't got that strong a signal (crappy weather has an effect) and so the registered movement is just noise.

You'd have to be doing very short rides with very long breaks for it to affect your average speed stats though I would have thought. A few seconds at 2mph as against a few hours at 15mph? Next time it happens leave the display on so that you can see your average speed and wait for it to drop 0.1mph. You'll probably still be waiting at Christmas

I don't stop for that long. I'm talking a couple of stops of a few mins over a rride of about 40 miles, it doesn't affect it that much but it certainly drops the avg by 0.1 or 0.2 mph, which I suppose, given the margin of error in registering GPS speed is irrelevant but it's still annoying!

Headhuunter

dhope wrote:

Sometimes with my 800 it happens, which is odd given that I've got the speed/cadence sensor too so it knows the wheels aren't moving.

So you're saying that's the only reason my average speed isn't up there with JZed? Interesting...

It even happens with the speed/cadence sensor? Weird.... Yes of course I would regsiter with Strava but with the innaccuracy of speed on the 500 means that JZed has an unfair advantage... or something...

rolf_f

Headhuunter wrote:

I don't stop for that long. I'm talking a couple of stops of a few mins over a rride of about 40 miles, it doesn't affect it that much but it certainly drops the avg by 0.1 or 0.2 mph, which I suppose, given the margin of error in registering GPS speed is irrelevant but it's still annoying!

Hmmmm, if you had a 5 minute break on a 3 hour ride at 15mph and for the whole of that 5 minutes the speed registered 2mph, by my reckoning your average speed would drop from 15mph to 14.67 mph. But that assumes a constant reading over the whole 5 minutes. When I've noticed the unit reading a speed when it's actually stationary, it has only been for a few seconds.

With the speed sensors - don't they operate in a hierarchy over the GPS speed calc? So if there is no signal from the sensor, then the GPS takes over.

SBezza

Just press the stop button when you have a break, it won't matter about the speed then when you start again, just press it again to start the timer.

essex-commuter

I used to judge a lot of my rides on average speed, I don't bother now. If lights changed in front of me I would leave my braking until the last moment rather than slowing down early and rolling across as they change, it's not a good way to ride (on relatively empty roads anyway). Thinking about how a lot of peeople drive their cars though...maybe they go on average speed..it's an accelerator not an on/off switch!

Headhuunter

SBezza wrote:

Just press the stop button when you have a break, it won't matter about the speed then when you start again, just press it again to start the timer.

Yeah I tried that on my last ride but a couple of times I forgot to press start again!

Headhuunter

essex-commuter wrote:

I used to judge a lot of my rides on average speed, I don't bother now. If lights changed in front of me I would leave my braking until the last moment rather than slowing down early and rolling across as they change, it's not a good way to ride (on relatively empty roads anyway). Thinking about how a lot of peeople drive their cars though...maybe they go on average speed..it's an accelerator not an on/off switch!

That's certainly true in the city/on the commute which is why I don't bother getting involved in SCR/Strava - as you say there are just too many other things affecting your speed, but once you're out in the country on a club ride it's mostly just you and the power you can push through the pedals so avg speed is a fairly good indicator of how well you're doing (in the absence of a power meter or other such expensive kit...)