# Garmin 500 Speed Sensor



## soccerdude (Aug 6, 2006)

The mount on my Echowell Zone 7 broke and I can't get a replacement so I decided to buy a Garmin 500. I would like to add a speed sensor to get a more accurate reading of speed and distance rather than use GPS data but I don't need or want cadence information. Is there a speed sensor for the Garmin 500 that doesn't have the cadence option? I'd prefer one that mounts to the fork rather than the chainstay. 

Thanks!

Soccerdude


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## Crack Monkey (Sep 25, 2006)

Not that I've seen. Just the combo wireless sensor. You can remove cadence from the display, so you won't see it if you don't want it. You could also just not install the cadence magnet, then it won't even be recorded.


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## slocaus (Jul 21, 2005)

soccerdude said:


> The mount on my Echowell Zone 7 broke and I can't get a replacement so I decided to buy a Garmin 500. I would like to add a speed sensor to get a more accurate reading of speed and distance rather than use GPS data but I don't need or want cadence information. Is there a speed sensor for the Garmin 500 that doesn't have the cadence option? I'd prefer one that mounts to the fork rather than the chainstay.
> 
> Thanks!
> 
> Soccerdude


No, only the GSC10, and you have to manually turn off the GPS each time you turn it on to use the speed sensor instead of GPS (useful for indoors trainers), or you have to loose GPS signal for an extended length of time for it to switch, and it will go back to GPS as soon as signal is reacquired. It will always record cadence from the sensor. All the Edge units work like this.

See page 42 of your Edge 500 Owners Manual


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## PissedOffCil (Oct 18, 2007)

I'm pretty sure the speed sensor could be setup on the fork but the provided tie-wraps might not be long enough. Once there, no need for teh cadence magnet.

Might I ask why you wouldn't want the cadence if it's free?


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## soccerdude (Aug 6, 2006)

Well that stinks. So if I'm hearing this right you can't use the GPS functions when using the speed sensor? 

As for cadence, it just doesn't interest me plus I'd rather have a sensor on my front fork rather than attached to my chainstay.


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## slocaus (Jul 21, 2005)

soccerdude said:


> Well that stinks. So if I'm hearing this right you can't use the GPS functions when using the speed sensor?
> 
> As for cadence, it just doesn't interest me plus I'd rather have a sensor on my front fork rather than attached to my chainstay.


Correct. You have to turn the GPS off to have the head unit use the sensor for speed and distance, like a conventional computer. Then you have to do a very accurate roll out, with the air pressure what you ride at, and sitting on the bike to make sure you get the accuracy. Others who have tested a GPS side by side with their old computer find the GPS to be very accurate.

Why do you want a GPS if you do not want to take advantage of the advanced technology it offers, with no sensors needed at all? If you want a sensor on your front fork, why not just use a conventional bike computer?

In my experience, a GPS is very accurate. Look at this picture closely.









It is detail of my commuter to and from work, but note that you can see that I am on the outside of a four lane road, and on the left turn off a two lane road to the four lane road, on the right again.

I use my 705 now to find old chaparral overgrown mining roads that can be ridden in some cases. I do not believe that a fork mounted magnet and sensor is more accurate, even with the most careful calibration; any time a mountain bike wheel is momentarily off the ground, the wheel sensor method looses accuracy, but the triangulation of the GPS never looses accuracy.


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## r70mtb (Aug 4, 2008)

Actually, you can try to pair it with third party ANT+ speed sensor. I'm using mine with speed sensor that came with VDO Z1 (mounted on the fork). From my experience you don't need to turn off GPS in order to use speed sensor. Data from the sensor is used for (at least current) speed calculation.


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## slocaus (Jul 21, 2005)

r70mtb said:


> Actually, you can try to pair it with third party ANT+ speed sensor. I'm using mine with speed sensor that came with VDO Z1 (mounted on the fork). From my experience you don't need to turn off GPS in order to use speed sensor. Data from the sensor is used for (at least current) speed calculation.


Here is an easy test to verify; have you done this?

If you have the bike in a work stand (stationary) and spin the wheel that the sensor reads, the speed shows, and average speed & distance accumulate?


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## soccerdude (Aug 6, 2006)

What I want most is to be able to use the GPS to create or follow a track and for the speedometer to be as accurate as possible. From my experience using my Etrex Vista the speed and distance can be way off. I know that a fork mounted sensor isn't close to 100% accurate but in my experience it's much better than GPS data.


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## Harold (Dec 23, 2003)

If you're basing your experience on an ETrex Vista (just the early basic one...not the H, HC, or HCx?), then you are missing out on a lot. Newer receiver tech and faster processors on these things improve accuracy and allow them to process more heavily degraded signals.

This means the position fix is more accurate and the GPS does not lose a signal very easily at all.

Your idea of using the speed sensor to augment speed/distance accuracy doesn't pan out very well with newer gear. It really is not going to be any different.


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## r70mtb (Aug 4, 2008)

slocaus said:


> Here is an easy test to verify; have you done this?
> 
> If you have the bike in a work stand (stationary) and spin the wheel that the sensor reads, the speed shows, and average speed & distance accumulate?


Basically this is what i have done when i mounted the sensor (i didn't check
the average speed though). When i got the 500, i used it without the sensor
and the speed readings were just annoying (one second you are going 20km/h,
in the next you are on 24, then 17 and so on). With the sensor, speed readings are consistent.


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## soccerdude (Aug 6, 2006)

r70mtb said:


> Basically this is what i have done when i mounted the sensor (i didn't check
> the average speed though). When i got the 500, i used it without the sensor
> and the speed readings were just annoying (one second you are going 20km/h,
> in the next you are on 24, then 17 and so on). With the sensor, speed readings are consistent.


That's what I'm afraid of. When the unit comes in I'm going to test it without a speed/cadence sensor first and see what happens. If it's not that accurate I'll look into either an ANT+ sensor or the one Garmin sells.


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## slocaus (Jul 21, 2005)

r70mtb said:


> Basically this is what i have done when i mounted the sensor (i didn't check
> the average speed though). When i got the 500, i used it without the sensor
> and the speed readings were just annoying (one second you are going 20km/h,
> in the next you are on 24, then 17 and so on). With the sensor, speed readings are consistent.


I remember seeing that speed issue in the Garmin Forums for the 500 now. Ah, the joys of new buggy firmware.  I had that with my 305, and waited over a year and a half before I got my 705, so almost no issues.



soccerdude said:


> That's what I'm afraid of. When the unit comes in I'm going to test it without a speed/cadence sensor first and see what happens. If it's not that accurate I'll look into either an ANT+ sensor or the one Garmin sells.


Well, it seems the 500 has some issues and I think only one firmware update so far. It looks like the ANT+ will work, according to r70mtb. Look in the Garmin forums, the GSC10 may work differently with the 500 than the 305/705 from what I read there. That info may be wrong, users do not always understand how their equipment works; if they did, these forums would not be so heavily used.


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## r70mtb (Aug 4, 2008)

soccerdude said:


> That's what I'm afraid of. When the unit comes in I'm going to test it without a speed/cadence sensor first and see what happens. If it's not that accurate I'll look into either an ANT+ sensor or the one Garmin sells.


The best way to test it without a sensor: Enable autopause mode and find a nice climb.
I did that and very soon my brain was melting as the thing constantly beeped. The first 
thing i had on TODO list after i returned was to put on a sensor.

Maybe it works better in the sunny weather but this year we had only one or two sunny days...


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## Crack Monkey (Sep 25, 2006)

slocaus said:


> If you have the bike in a work stand (stationary) and spin the wheel that the sensor reads, the speed shows, and average speed & distance accumulate?


Yes, see these two activities in Connect:

Indoor trainer, GPS on...
http://connect.garmin.com/activity/23884730
Note: the map shows the GPS "drift", but the splits and player accurately show speed and cadence based on GCS-10 output.

Indoor trainer, GPS off (concrete building, no signal)...
http://connect.garmin.com/activity/23884734
Note: no map data, because GPS was turned off (when it can't find signal, it asks if you want to continue without GPS or keep searching for signal). Again, speed/cadence data is correct via the GCS-10.

Edit: Page 42 of the manual linked above shows how to turn off the GPS manually, and record only the GCS-10 data. BUT, you don't have to do this - you just end up with garbage GPS data like in my first workout (so, either turn GPS off, or ignore the GPS data).


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## dcrainmaker (Feb 9, 2010)

It's somewhat important that you do shut off the GPS when indoors on a trainer. The reason being that without doing so you'll see some applications that don't support having two concurrent streams of speed data.

This is due to the way the data files are recorded. In one data stream you have the GPS data points (coordinates), and in a secondary data stream you have the distance as reported by the sensor (timestamps are then used to determine actual speeds). Most applications (Garmin Connect, GTC, Training Peaks), pickup the speed sensor and use that data. But some applications (Sport Tracks), will use the GPS speed first, and then not use the cadence speed sensor until specifically told to do so. If you don't tell it to do so, then it'll basically show that you've only gone a few hundred feet (GPS variances).

I wrote a bunch about it here in this post, including pictures of how it all works.

Also, a quick note on autopause (it was mentioned above) - you can easily tweak its default settings. Autopause has a minimum speed threshold (which I honestly find too fast, so I lower it even further). It's possible if you're on a super steep hill (such as in the woods), you'd be below that threshold. Simply tweak that, and you'll be good to go.

Anyways...more detail than you probably wanted...


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## soccerdude (Aug 6, 2006)

My Edge 500 came in the other day so I gave it a few test spins. The GPS is excellent regarding positioning but as I feared it's not that great at giving an accurate speed reading. I've decided to buy a speed sensor for it but don't know which one will work best. Is the Garmin speed/cadence sensor strong enough for intermediate mountain bike trail use? I understand that the Edge 500 can use ANT+ sensors but who sells a good sensor that won't rob the bank? I'd prefer one that mounts to the fork but that's not a deal breaker. Thanks for all the advice so far. It's been extremely helpful.


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## slocaus (Jul 21, 2005)

Make sure that it has the updated firmware right away. As I stated, there have been speed issues posted in the Garmin forums, take a look at those too. But update the firmware before you do anything!


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## soccerdude (Aug 6, 2006)

I updated the firmware the second I took it out of the box. I've owned a few Garmin Nuvi GPS's and understand the importance of firmware. My Nuvi 855 is still buggy after 3 firmware updates but it's getting better. So far I'm pretty happy with the Edge 500. It has most of the features I wanted with the exception of being able to add topo maps to the unit. I didn't want to pay extra dough for the Edge 605 or 705 plus I wanted a temperature reading which neither one has. I also like that the Edge 500 is much lighter. If I can find a good solution for the speed reading I'll be very happy.


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## PissedOffCil (Oct 18, 2007)

soccerdude said:


> Well that stinks. So if I'm hearing this right you can't use the GPS functions when using the speed sensor?
> 
> As for cadence, it just doesn't interest me plus I'd rather have a sensor on my front fork rather than attached to my chainstay.


You're not really answering why you don't want cadence if it's free and why you want it on the fork either... Are we talking a FS here? If that's the case, not all FS designs aren't cadence sensor friendly...


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## slocaus (Jul 21, 2005)

soccerdude said:


> I updated the firmware the second I took it out of the box. I've owned a few Garmin Nuvi GPS's and understand the importance of firmware. My Nuvi 855 is still buggy after 3 firmware updates but it's getting better. So far I'm pretty happy with the Edge 500. It has most of the features I wanted with the exception of being able to add topo maps to the unit. I didn't want to pay extra dough for the Edge 605 or 705 plus I wanted a temperature reading which neither one has. I also like that the Edge 500 is much lighter. If I can find a good solution for the speed reading I'll be very happy.


Good luck, it sounds like the ANT+ one might work. Here is hoping that it is not totally a firmware issue, and that it actually works fine for you with just the GPS function. Garmin has made good progress in that, my 705 is much more accurate than my 305 was in recording tracks.


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## smittylube (Mar 21, 2009)

As I understand it will only help you have an accurate speed adding the speed sensor, and input the wheel size. Your not turning off the gps only adding the speed sensor.

Steve


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## dnoyeb (Sep 23, 2007)

I've been using a 305 for a long time and don't have any speed accuracy issues. Even if I do, whats the big deal if it momentarily bounces to some odd speed? It recovers so fast, if it didn't you wouldn't even notice the speed was off. And the recorded data will more than likely not have that speed bump.

Plus, on the 305, you can turn the GPS to record more frequently, which I do sometimes when I am recording a "course."

I know you have your reasons, but I think the accuracy of the GPS is pretty good and reliable. At least in my area it is. Maybe your riding somewhere that the signal gets blocked more frequently that usual!?


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## slocaus (Jul 21, 2005)

dnoyeb said:


> I've been using a 305 for a long time and don't have any speed accuracy issues. Even if I do, whats the big deal if it momentarily bounces to some odd speed? It recovers so fast, if it didn't you wouldn't even notice the speed was off. And the recorded data will more than likely not have that speed bump.
> 
> Plus, on the 305, you can turn the GPS to record more frequently, which I do sometimes when I am recording a "course."
> 
> I know you have your reasons, but I think the accuracy of the GPS is pretty good and reliable. At least in my area it is. Maybe your riding somewhere that the signal gets blocked more frequently that usual!?


The 500 had speed issues in the early release that the 305 did not. See the Garmin forums for more info.
https://forums.garmin.com/showthread.php?t=7288&highlight=speed
https://forums.garmin.com/showthread.php?t=6580&highlight=speed
https://forums.garmin.com/showthread.php?t=5309&highlight=speed
https://forums.garmin.com/showthread.php?t=5168&highlight=speed

The 305 had its issues, like battery drain and battery accuracy when it was first released.

The 705 had altitude issues with the early release. It is very common for Garmin hardware to have firmware issues when released. Early adopters are usually beta and sometimes alpha testers.


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## soccerdude (Aug 6, 2006)

Well I sent the Garmin 500 back as it was too buggy and not very accurate regarding speed. It did a great job of tracking my path but often if you loaded a track onto the gps then tried to follow it the unit would lock up. Also the speed was off quite a bit. I know most gps' aren't great at tracking speed but this was worse than my old Etrex Vista! When I added the speed/cadence sensor it worked much, much better. I decided to purchase a VDO MC1.0+ bike computer which is the best I've ever used and also a new Etrex Vista HCX for when I need gps capability. The new Vista HCX is much larger and heavier than the Garmin 500 but it has tons more features and does not crash. 

I've been a huge supporter of Garmin in the past but that is quickly starting to change. I've owned a Garmin Nuvi 200W, an Etrex Vista, and an Etrex Vista HCX and never had any problems with them. But within the last year I also purchased a Nuvi 855 and the Garmin 500 and have had tons of problems with them. Firmware updates are not helping. I strongly believe that Garmin has trouble writting software for devices with multiple features. My Nuvi 200W was just a straight up GPS and it never once crashed but my Nuvi 855 has voice activation, mp3 player, multi-point routing, traffic avoidance, plus other stuff an it crashes at least twice a month. The Garmin 500 does lots of stuff other than just GPS things and it crashes too. Garmin better get their act together or they're going to lose business.


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## Wildeyes (Jun 14, 2007)

My experience is that Garmin don't do a very good job at all of troubleshooting devices before their initial release. I can see some bugs to iron out, but Garmin's stuff is really awful when it first comes out, needing countless updates to get it to work as advertised. They must outsource programming to Toyota engineers.


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## EBrider (Aug 3, 2004)

I haven't had any issues with the 500 after about 2 months.


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## jkmacman (Mar 5, 2009)

My sensors seem to eat batteries. I have 2 garnin hrm straps and cadence sensors on 2 road bikes. The 32 20 seem to wear out after a few months on the cadence sensor.


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## slocaus (Jul 21, 2005)

Yeah, WTF, my flashlight batteries keep running down too and I have to replace them!?


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## jkmacman (Mar 5, 2009)

just yesterday was earthday. i try and avoid disposable batteries, as i recharge aaa and aa, the 32 20, while small is still a battery, that being said i'm interested in the edge 500, but i don't replace the cadence sensors immediatly after they die, if i am conscrious of the cadence i can improve it:thumbsup:


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## digibud (Sep 21, 2009)

I bought a 500 on 6/7 or so and on the third use went up a stupid steep hill about 6mi long. At one point I was going about 2.8mph and had to stop. Shortly after starting up my speed went to zero and the grade percent disappeared. This happened more than once on the ride in spite of the cadence unit. I now know I could have turned off the GPS but I was on a road and the trees were not THAT tall. I have extensive experience with GPS units and any good GPS unit should have maintained the signal where I was. I could have turned off the GPS but then it's not worth the price of the 500. Had I been in a dense forest I would have understood. I returned the unit. Too bad. It was flexible and having the cadence, altitude, heart rate and all the functions were great. The GPS simply failed to work well. ( I have three other Garmin GPS units. I'd like to double check there use where i was but that's unlikely).


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