Issue with new Garmin 500 GSC 10 speed sensor

[auswi2]

Gidday,

I purchased a Garmin edge 500 with the speed/cadence sensor on Australia day. I went out for my first outdoor ride today due to the rain in Brisbane and the Garmin picked up the speed/cadence sensor when I started the ride but my speed of the back wheel was all over the place showing 50kph when i was only doing 20 and it showed a max speed of 170kph (I Wish I was going that fast). I stopped and adjusted the spoke magnet and adjusted the arm so the gap was really close without touching but still the speed was not right. I have manually set the rear wheel circumference for a 700x23 2096 on the 500.

I cant find anything in Garmin support which tell me my unit is possible faulty or I have set something up wrong.

The cadence on the other hand was perfect so I moved the speed sensor arm away from the spoke sensor and restarted the edge 500 and done the rest of my ride using GPS for speed which seemed very accurate.

Any suggestions

auswi2

[kb]

Stupid question but you haven't changed from another speedo an accidentally ended up with two magnets?

[Le Velo]

I know you said its new but my garmin tend to do that when the battery in the sensor is in need of being changed ....

[auswi2]

My old speedo had a front wheel sensor and the battery is fully charged in the head unit not sure how old the battery is in the GSC 10. Would a dead battery also affect the cadence which is fine.

thanks

auswi2

[RonK]

It's not at all uncommon, the Garmin forums have been full of complaints about flat batteries in GSC10 sensors since they were introduced with the Edge 305. Don't mess around, get a new one - CR2032 I think.

[auswi2]

I believe i have found the problem and it was from my end.

When I went out I did not turn the GPS off so I would have been receiving data from 2 sources. I spun the rear wheel on my trainer with the GPS turned off and it seemed accurate. is that correct that you need to turn the GPS off if using the Speed/Cadence sensor

auswi2

[you cannot be sirrus]

I believe i have found the problem and it was from my end.

When I went out I did not turn the GPS off so I would have been receiving data from 2 sources. I spun the rear wheel on my trainer with the GPS turned off and it seemed accurate. is that correct that you need to turn the GPS off if using the Speed/Cadence sensor

auswi2

No, I never turn my GPS off, try the battery as has been suggested as a first step.

[auswi2]

Thanks I will

[Comedian]

If it's reading double then the magnet could be incorrectly aligned and the north and south pole is passing the sensor giving a double reading. I had this problem and turning the magnet 90Deg fixed the problem.

Those sensors are also really finicky to magnet alignment. Once they are set up they are all good though.

[sumgy]

I am confused here.
Why would you turn off the GPS and use a magnet except for while you are on a wind trainer?
The GPS will tell you your speed at least as well as a magnet and you dont need to change your settings when you move the Garmin from bike to bike.
FWIW I dont think that your solution is the right one as I have had a magnet on my back wheel for some time (so that I have it there for when I am on the trainer) and never have the issue that you have raised.

[Comedian]

I am confused here.
Why would you turn off the GPS and use a magnet except for while you are on a wind trainer?
The GPS will tell you your speed at least as well as a magnet and you dont need to change your settings when you move the Garmin from bike to bike.
FWIW I dont think that your solution is the right one as I have had a magnet on my back wheel for some time (so that I have it there for when I am on the trainer) and never have the issue that you have raised.

Gps don't do elevation well. Ie... When climbing or descending speed and distance will under read.

Garmin seem to use the sensor, gps, and barometer to sort it... Very clever.

[mmhbeer]

The Garmin 500 uses the wheel magnet to read your speed when you lose GPS reception eg in a tunnel, in a valley, under tree cover.

When you first go for a ride it picks up the magnet and then after about a km it calculates the wheel size for you.

I use a rear wheel speed sensor with my Garmin on my MTB. I had noticed that it would beep and auto pause when doing switch backs prior to fitting it, resulting in it reading rides a bit shorter than they are. All good with the magnet fitted.

[auswi2]

If you have a cadence/speed sensor and have paired it with the head unit the Edge 500 will utilize the data from the sensor and the only time the GPS will calculate speed is if there is no speed/cadence sensor or the sensor arm is to far from the magnet.

thanks

auswi2

[twizzle]

If you have a cadence/speed sensor and have paired it with the head unit the Edge 500 will utilize the data from the sensor and the only time the GPS will calculate speed is if there is no speed/cadence sensor or the sensor arm is to far from the magnet.

thanks

auswi2

No.

[auswi2]

When you say no which section are you saying no to.

This info has come direct from Garmin Support staff.

auswi2

[hanzao]

If you have a cadence/speed sensor and have paired it with the head unit the Edge 500 will utilize the data from the sensor and the only time the GPS will calculate speed is if there is no speed/cadence sensor or the sensor arm is to far from the magnet.

thanks

auswi2

Yes this is true

[sumgy]

The Garmin 500 uses the wheel magnet to read your speed when you lose GPS reception eg in a tunnel, in a valley, under tree cover.

When you first go for a ride it picks up the magnet and then after about a km it calculates the wheel size for you.

I use a rear wheel speed sensor with my Garmin on my MTB. I had noticed that it would beep and auto pause when doing switch backs prior to fitting it, resulting in it reading rides a bit shorter than they are. All good with the magnet fitted.

Adjust auto pause to 0km/h.
Sorry, I still dont see the point of using a magnet when you have GPS.
Then again I dont seem to have had the issues others have had.

[twizzle]

When you say no which section are you saying no to.

This info has come direct from Garmin Support staff.

auswi2

And they are wrong in the way they have described it. The only time you are reliant on the speed sensor is if you disable GPS. Otherwise, it will use both sources and over-ride the wheel size to make the speed sensor match the GPS... unless you have set the wheel size manually, which is a daft thing to do.

[twizzle]

The Garmin 500 uses the wheel magnet to read your speed when you lose GPS reception eg in a tunnel, in a valley, under tree cover.

When you first go for a ride it picks up the magnet and then after about a km it calculates the wheel size for you.

I use a rear wheel speed sensor with my Garmin on my MTB. I had noticed that it would beep and auto pause when doing switch backs prior to fitting it, resulting in it reading rides a bit shorter than they are. All good with the magnet fitted.

Adjust auto pause to 0km/h.
Sorry, I still dont see the point of using a magnet when you have GPS.
Then again I dont seem to have had the issues others have had.

Both of mine died within weeks of each other, couldn't be arsed wasting more money on another one. The early units are very unreliable due to moisture ingress, the later ones are marginally better. There's a good write up on the net explaining how to rebuild them to be reliable.

[mmhbeer]

The Garmin 500 uses the wheel magnet to read your speed when you lose GPS reception eg in a tunnel, in a valley, under tree cover.

When you first go for a ride it picks up the magnet and then after about a km it calculates the wheel size for you.

I use a rear wheel speed sensor with my Garmin on my MTB. I had noticed that it would beep and auto pause when doing switch backs prior to fitting it, resulting in it reading rides a bit shorter than they are. All good with the magnet fitted.

Adjust auto pause to 0km/h.
Sorry, I still dont see the point of using a magnet when you have GPS.
Then again I dont seem to have had the issues others have had.

The problem is that when using gps it might take a reading say every 5 seconds. In that five seconds I might have done a switch back corner and then it takes it's reading again. This results in straight lining corners, giving oh a shorter riding distance.

It's not an issue on a roadie, only on the Mtb on twisty singletrack. If you export your data to google earth you can see the difference. You will see where the lines that it draws don't line up with the singletrack.

[twizzle]

Adjust auto pause to 0km/h.
Sorry, I still dont see the point of using a magnet when you have GPS.
Then again I dont seem to have had the issues others have had.

The problem is that when using gps it might take a reading say every 5 seconds. In that five seconds I might have done a switch back corner and then it takes it's reading again. This results in straight lining corners, giving oh a shorter riding distance.

It's not an issue on a roadie, only on the Mtb on twisty singletrack. If you export your data to google earth you can see the difference. You will see where the lines that it draws don't line up with the singletrack.

Easily solved - If you use a power meter with the Edge500 it will record every second instead of using 'smart' recording.

[casual_cyclist]

I know you said its new but my garmin tend to do that when the battery in the sensor is in need of being changed ....

I just had to replace the battery in mine and then re-pair. Seems to be working well after that.

[twizzle]

I had a look at my dead onces a couple of months ago. One was just having pairing issues, but the reed switch in the arm of the original one had failed. They don't have an infinite life, but it was probably only 18 months old when it carked it.