Garmin 500 with cadence question

[SteveV0983]

I have a question to anyone specifically using a Garmin 500 with the optional cadence sensor. Do these things calculate your distance and speed via GPS or is it via a speed/distance sensor? The optional GSC10 says it comes with a speed sensor, so it makes me think it does not use GPS for speed and distance. I prefer a sensor.

[1centaur]

From memory of the early Garmins, it's a software switch that favors GPS when available and uses the sensor when the GPS goes out, but probably trues up back to the GPS when that becomes operational again. The reason I dropped the cadence sensor was that it took too long to switch over to the sensor, so when going through sporadic tree cover I'd get annoying sequential multi-second lags of data. Of course, without the sensor the GPS still drops out the same way but I learned to live with the lack of moment by moment data rather than the annoyance of hoping for the switch over faster than it would ever be.

[svelocity]

I have a Garmin 500 and IIRC speed and distance are calculated using the GPS. You can ride without the speed and cadence sensor and still record all of the trip data sans cadence of course; however, if you use the speed/cadence sensor the Garmin 500 will "true up" your ride data and make it more accurate. While using the speed/cadence sensor I believe it calculates your wheel circumference based on the GPS reading and the rotations of your wheel.

Again this is what I recall without re-reading the documentation.

Cheers!

[fuzzalow]

When the 500 is paired off with a GSC-10 cadence/speed sensor, it takes speed & distance data from the GSC-10 unit while it measures rear wheel rollout. More accurate if the rollout is actually measured and the distance entered into the bikes profile.

[SteveV0983]

Thanks for the responses. But it sounds like it's more trouble than it's worth to me.

[svelocity]

Thanks for the responses. But it sounds like it's more trouble than it's worth to me.

FWIW Setting up the sensor takes maybe 15 mins, 5 mins if you are not drinking a beer at the same time. If you ever use a trainer you'll need the sensor.

Cheers!

[thirdgenbird]

FWIW Setting up the sensor takes maybe 15 mins, 5 mins if you are not drinking a beer at the same time. If you ever use a trainer you'll need the sensor.

Cheers!

x2. I've got one on my bike that sees time in a trainer.

[shovelhd]

The GSC-10 is not the only option. Bontrager makes a nice line of ANT+ sensors that work fine with a Garmin.

[Helicomatic]

Thanks for the responses. But it sounds like it's more trouble than it's worth to me.

No trouble required. You do not have to do any measuring or enter any info to calibrate. The system does this for you.

You can use the cadence sensor without using the wheel sensor. Leave the magnet off your wheel and it will ignore it. As noted, if you are moving your 500 from bike to bike, you do need to pair it with the right cadence sensor. Once you figure it out, it takes about 30 seconds.

If you use the wheel sensor, the system automagically uses the wheel data to improve the accuracy of the GPS data. With the wheel sensor, it will be accurate to a few feet. This is especially helpful if you ride places where the GPS data is at all flaky. E.g. if you ride tunnels or some mountainous areas.

When you first get on the bike, the unit will start counting wheel rotations and doing GPS measures. After about 1/2 a mile it will tell you it has completed calibrating the wheel sensor. This auto calibration allows you to change wheels and tires, and averages out road conditions. I've never had to enter a calibration for the wheel sensor.

I don't have documentation for this, but it appears that it may check it's internal calibration from time to time.

Bottom line. Get the cadence sensor if you want cadence information. Get the wheel sensor if you want more reliable and repeatable GPS data.

[russ46]

One advantage to using the speed/cadence sensor is more accurate speed while you are riding. Without it your displayed speed will frequently lag your actual.

[Lewis Moon]

FWIW Setting up the sensor takes maybe 15 mins, 5 mins if you are not drinking a beer at the same time. If you ever use a trainer you'll need the sensor.

Cheers!

Heh!....correct. A while back it was raining so hard I couldn't make it out of the garage w/o my rims filling up, so I got on the trainer. 45 minutes (and one Torchwood episide) later I got off the trainer soaked to the bone and beat. I fired up the 'puter to log the workout only to find the milage total was 0.2 miles. The antenna worked through the garage roof. Go figure. You should have seen the map....

[Lewis Moon]

One advantage to using the speed/cadence sensor is more accurate speed while you are riding. Without it your displayed speed will frequently lag your actual.

At what interval does the data get recorded? Because I use an Edge 305 (500 precursor), I ride with it in my pocket to prevent the sudden shutoff syndrome. For the time being (until I get the 305 modified) I use my old Node 1 on the handlebars. I've noticed I can drive my HR up into the mid 180s, but will only see ~172 on the Garmin data.

[parallelfish]

When the 500 is paired off with a GSC-10 cadence/speed sensor, it takes speed & distance data from the GSC-10 unit while it measures rear wheel rollout. More accurate if the rollout is actually measured and the distance entered into the bikes profile.

Ding! This is the correct answer.

Measure and enter the roll out manually, and keep the GPS out of the speed/distance measurement.

[Jason E]

Anyone having their 500 go wonky? It stopped reading the power on the trainer, and even though it WAS syncing back and forth between the Garmin Speed/Cadence and the Bontrager Speedtrap, or whatever, but now it won't sync to the Bontrager at all. I select rescan and it wont.

Lastly, Sunday it said I registered a 223 in an area with no interference, powerlines, or history of interference.

Sorry for the minor re-steer/hijack.

frustrating.