When a speed sensor is paired to a Garmin device, speed and distance data is recorded by the sensor which overrides GPS data collected by the watch. If you experience erratic data or issues with data being recorded, review the following steps to solve these problems:
with a FIT file viewer you can check the source of the speed data in the file. but the pattern of the speed curve on the speed chart is also different a bit if you analyze it on Strava (the gps speed is a bit jaggy, the speed sensor has much smoother curves.)
If the speed sensor is paired with a good battery it will use it. With an active pairing you can select auto or set a wheel size. I prefer auto because I move the 830 between several bikes with different wheel sizes. One way to tell is that speed sensor reading are very steady. With the GPS only it tends to jump around a bit, especially under dense tree cover or other places where satellite signals may be intermittently obstructed.
prefer auto because I move the 830 between several bikes with different wheel sizes.
And I am afraid it makes no sense at all. You specify the wheel size not for your Edge, but for your speed sensor(s). So even if you use your 830 with more bicycles, the speed sensors of these bikes “know” the wheelsize of the actual bicycle.
The only problem would be if you had one speed sensor and you always moved it between your horses unzipping and re-zipping the sensor.
And I am afraid it makes no sense at all. You specify the wheel size not for your Edge, but for your speed sensor(s). So even if you use your 830 with more bicycles, the speed sensors of these bikes “know” the wheelsize of the actual bicycle.
Auto mode sets wheel size automatically on the edge when you begin your activity. If you move your sensor to a different wheel the Edge will set an appropriate size. The sensors are dumb, they only communicate round and round. I have speed sensor on each bike that I regularly ride. There is no manual setting required as I move the Edge from bike to bike. Gravel, MTB, road, winter beater; when I switch wheels on the gravel bike I move the sensor. The current generation of wheel sensors do not require any zip ties.
Beware that the Garmin Speed Sensor 2 relies on the earth's magentic field to count the wheel's revolutions. This means that if you drive over constructions containing steel (bridges, underground garages, ...), this sensor likely won't count correctly (experienced that myself often). On top of that, the Edge 830 does not have a precise/reliable GPS chip, and of course also depends on obstacles affecting satellite reception (building, trees, ...). Both factors can/will affect your automatic calibration of the speed sensor - depending where you ride during this calibrarion.
I prefer to set the wheel size manually. It's easy enough to measure. Best is to sit on your bike when your wheel makes one or more complete revolutions, so you take into account the effect of the deformation of your tire - hence the circumference of your wheel - due to your weight.
Yep, and apply some pressure in tires which can be regarded as a average one in the long term.
I do the same that you wrote.
People underestimate the effect of the tire deformation.
10 years ago I even made a comparison between mounting one sensor in the front fork and mountin one on the rear. Just to know how big effect there is if you are climbing for an hozr and sitting vs pedalling out of the saddle. Finally I decided that it is the better to stick to the first wheel/fork.
By the way all my speed sensors are from the 1st generation and I mount magnets on spokes, it is why I was writing about zipping. When Garmin and the big names seemed to produce this type I went for Sigma Speed sensor to replace my died older Cyclops and iBike speed sensors.
I prefer to set the wheel size manually. It's easy enough to measure. Best is to sit on your bike when your wheel makes one or more complete revolutions, so you take into account the effect of the deformation of your tire - hence the circumference of your wheel - due to your weight.
I did this for a couple of decades. There is no practical noticeable difference. The error is likely less than what you get because you don't ride a bike in precisely a straight line. I'm going to stick with the auto slap on a sensor and go system. In any given season of thousands of miles with multiple bikes plus or minus a few a few yards is not on my radar. Grade delay on the other hand realy trips my trigger ;-)
