Garmin Speed Sensor Woes

bungle73

I've got an Edge 800, and I recently got a Garmin speed sensor off eBay. I've got auto pause turned on, but the issue is that it keeps activating for no apparent reason, even though I'm still moving. Just been out today, and it happened several times. If I'd not been using a sensor I would have said the tree cover was obscuring the GPS, but I was. Any ideas? Dying battery maybe?

step83

You more than likely need to set the auto pause option on the garmin to something like 4kph (I had to on mine) should solve the issue. It does dip in an out under heavy tree cover though.

bungle73

Step83 wrote:

You more than likely need to set the auto pause option on the garmin to something like 4kph (I had to on mine) should solve the issue. It does dip in an out under heavy tree cover though.

Thanks. But why would it dip out because of trees? I don't see why they would affect it?

super_davo

Is it the new style with no magnet? If so, I have a similar issue on my 800. It drops the signal, causing the Garmin to think I have stopped so going to auto pause. Doesn't happen on my GSC10. I have just stopped using it; it loses a small amount of accuracy vs having a sensor working properly, but gains a lot vs a sensor that drops out every 5 minutes or so!

Sutton_Rider

super_davo wrote:

Is it the new style with no magnet? If so, I have a similar issue on my 800. It drops the signal, causing the Garmin to think I have stopped so going to auto pause. Doesn't happen on my GSC10. I have just stopped using it; it loses a small amount of accuracy vs having a sensor working properly, but gains a lot vs a sensor that drops out every 5 minutes or so!

Exactly the same. I've taken mine off the bike. I know someone with an Edge 1000 and it does the same.

ayjaycee

I bought the speed sensor in a set with the cadence sensor BNIB but have never actually used it! However, the cadence sensor gave me problems out of the box by freezing my Garmin Edge 500 about five miles into every ride. I changed the battery and the problem went away. For the sake of a 20p battery, it's probably worth trying the same before you bin it.

Sutton_Rider

It's not the battery in this case, it's a Garmin design fault, from what I understand most of them do it.

wongataa

I have an Edge 800 and the Garmin magnetless speed and cadence sensors. They have never been any trouble and worked without issues except when the batteries have died. New batteries sorted that problem.

dabber

wongataa wrote:

I have an Edge 800 and the Garmin magnetless speed and cadence sensors. They have never been any trouble and worked without issues except when the batteries have died. New batteries sorted that problem.

The same for me with my G520... no problems and I regularly swap them between bikes which is very quick to do as there is no setup required.

bungle73

super_davo wrote:

Is it the new style with no magnet? If so, I have a similar issue on my 800. It drops the signal, causing the Garmin to think I have stopped so going to auto pause. Doesn't happen on my GSC10. I have just stopped using it; it loses a small amount of accuracy vs having a sensor working properly, but gains a lot vs a sensor that drops out every 5 minutes or so!

Yeah, it's the new style.

step83

The drop out is due to it relying on the GPS basically saying yes your not on a stationary trainer (ie your gong from A to B not just spinning the wheel.
The GSC10 had a cadence sensor built in where the new one doesn't, since I added a power meter with cadence I don't tend to get it.

bungle73

Step83 wrote:

The drop out is due to it relying on the GPS basically saying yes your not on a stationary trainer (ie your gong from A to B not just spinning the wheel.
The GSC10 had a cadence sensor built in where the new one doesn't, since I added a power meter with cadence I don't tend to get it.

That doesn't make any sense to me. Why would you want auto pause to come on if you were on a trainer? Not to mention the fact that the whole point of using a sensor is so that you don't have to rely on GPS.

Sutton_Rider

Where did you get that info Step83? - The whole point of the speed sensor is that it DOESN'T need a GPS signal.

wongataa

Step83 wrote:

The drop out is due to it relying on the GPS basically saying yes your not on a stationary trainer (ie your gong from A to B not just spinning the wheel.
The GSC10 had a cadence sensor built in where the new one doesn't, since I added a power meter with cadence I don't tend to get it.

If you have an active speed sensor paired with your Garmin head unit the head unit will use the speed sensor info for speed and will not use the GPS for speed. If the head unit can't detect the speed sensor then it will switch over to using GPS for speed. If the connection between the speed sensor and head unit is not good (say for example the battery is going in the sensor) then the head unit may keep switching between using GPS and the speed sensor for speed which will show as odd readings on the head unit.

A cadence sensor has no affect on how the head unit works out the speed.

thomasmorris

I've had this problem with the newer hub mounted speed sensor. Does it on both 500 & 1000.

At first I thought it was bumps / vibrations which were messing with what must be an accelerometer in the unit, making it think the wheel had stopped and activate the auto-pause. I've never completely ruled this out.

For a long time I switched off auto-pause as the constant bleeping was doing my head in.

I moved the sensor to the front hub, nearer the head unit, and it seems to have fixed the problem. Replacing the battery also helped too. I still get the very occasional drop, but not enough to worry about.

It's certainly nothing to do with GPS as I get dropouts indoors on the trainer with GPS turned off.

bungle73

Thanks. I think I'll try changing the battery first (I've no idea how old the one in there is, since it's second hand), and then try moving the sensor to the front hub.