speed sensor issue with Garmin 800
 

I replaced my wheelset this weekend on my commuter. I have found that when the speed and cadence sensors are paired to the Garmin it pauses and resumes all the time. It was so annoying on the commute in that I turned off the sensors.. I know it is not the GPS because when sensors are turned off it does not do it. I have also used it on another bike and it does not do it as well. I think it is the speed sensor messing up..

Could I have messed something up switching the speed sensor from one hub to the other? They are both on the rear wheel does that matter? I wiped it down with a paper towel to take some of the road grime off of it. (but should that matter considering it has been ridden in the rain?

is there a way to reset the speed sensor? how long should the battery last?

any advice?

Haven't had that issue, but if the sensor is set correctly on the bike, I would suspect the battery.

I would think if you ride the bike almost everyday and it's been over a year it would probably be a good idea to replace the battery. Replacing the battery will probably require that the sensor recalibrate. According to the ads the recalibration requires the bike to be outside and moving forward.

If you replace the battery a good idea would be to clean the electrical contacts to remove any oxidation. Also check to make sure there is enough pressure on the contacts to make a good electrical connection with the battery. ( I don't own a Garmin sensor so I don't know if there is another way to recalibrate the sensor )

@01 CAt Man Do
thanks for the advice. I cleaned it out and it recalibrated as rode up the street.. seemed to be working fine but then it started doing it again. I guess I will just try to find some CR 2032 batteries and replaced in the speed and cadence sensors and see if that gets me more accurate readings again.

I am thinking it is the speed sensor bc cadence can stop anytime during a ride and would not affect pause/ resume functionality. I guess I will replace both batteries so they are fresh together. I have had the sensor since 10-2015 but I am not sure how long it sat on the shelf.

I had the old, magnet-based GSC-10 and still have my 800. I was never able to get the speed sensor to work reliably, it would often display zero. I ultimately gave up and have been using GPS for speed ever since, with no ill effect.

Learn my on the need for a speed sensor ?.

I kept my Cateye sensors on my bike when I added a Garmin 810 and do notice that there's a slight lag on the 810, maybe 3-5 seconds at best ?, of current speed. Distance seems to be off about a mile in 100 and the auto-stop/start is different as well, so I guess ride distance/time/avg. is different, but somewhat a "so what".

So why do these exist ?.

They don't add miles from GPS drift, work in areas with spotty GPS signals, and work on trainers.

While speed is meaningless on trainers, it's nice to know fast different tires and chains wear out so you know what to buy next. I found that I got about half the life out of GP4Seasons compared to Gatorskins; and GP4000s which are even faster didn't wear out any quicker than Gatorskins. Without a reasonable tire-distance-traveled estimate you couldn't know that.

They may also keep your computer map display pointed in the right direction when you stop with a computer lacking a magnetic compass. While GPS drift can trick the computer into thinking you're moving and changing directions, 0 speed from a sensor should let the computer assume you're still facing the same direction.

That can be a big deal when you're 20 hours into a ride (you don't think as well at that point), it's after midnight (you may be unable to read street signs without a helmet mounted light, and aren't wearing one because that's tiring potentially leading to Shermer's neck), and you're in an unfamiliar location.

When working properly, the wheel sensor improves auto-pause operation because it's free of the effects of GPS drift and position noise. I set auto-pause to 3mph using a wheel sensor, but or 6 mph when relying on GPS. For the slower going mtb, I use two wheel magnets at 180 degrees so that the Garmin gets more frequent pulses. With two magnets, the wheel circumference is set to 1/2 actual in order to read speed correctly.

Thanks Loo and Drew

I don't do your distance so have not yet had to deal much with drift and don't use a trainer (have one, hate it). I could see maybe a sensor on my mt. bike next fall though if I see GPS dropout. My iPhone used to track those rides pretty close, will see how the 810 does.

Good explanations and examples though.