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Unstable Speed with Speed Sensor connected

Anyone else experiencing fluctuating speed values? Connected is a Garmin wheel speed sensor (Ant+) and for whatever reason (FW update?) the speed jumps around. I deleted and reconnected the sensor, and I replaced the sensor battery. No change. Any help is highly appreciated!

Top Replies

6228927 over 5 years ago +2

Garmin sensors are too sensitive to type of road etc. I bought Wahoo. Not problem at all. They are far superior and they communicate with my Garmin 1030.
pdxfisher over 7 years ago +1

I know I have seen posts about chains becoming magnetized and interfering with sensors on back wheel. If it is on your rear wheel you might want to try moving sensor to front hub.
Wooooooooo!!!!!! over 4 years ago +1

Same issue. called customer support. after chatting a while, the rep reveals this is a common complain and that there is no fix for it.... Think I;ll go back to the old magnet sensor. This magnetomer based…

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0 Former Member over 7 years ago

I guess not everybody is paying attention :) Original poster already said he tried to re-pair it, and changed the battery.
My sensor is on the front hub, and as I already stated, speed is going like crazy. Ocassionaly it starts the ride as well, although I haven't moved. All that after 5.0 update.

0 Former Member over 7 years ago

I just posted a separate topic on this issue. My speeds appears to jump back and forth from normal to half speed. Also using 5.0.

0 Mark.lewis1001 over 7 years ago

This issue has also been mentioned on the 520 plus forum with the new 2.60 update for your information.
????

0 hajo_s over 7 years ago

I'm very sure it's a bug. It happened for a long time with my 800 until one day it disappeared. I saw it with my new 1030 but recently it doesn't seem to happen any more. Haven't tried 5.0 much yet.

I saw it most frequently on/next to/under bridges. I suspect the GPS jumps there and somehow the FW takes GPS speed info although the sensor is paired. Or there's whatever interference around bridges. Happened both with old magnet sensors and with new hub type.

0 Lutzger over 7 years ago

I can confirm that for me it was because of a magnetized chain. Switched the sensor to the front wheel and it works like a charm!

0 Former Member over 7 years ago

Great advise! I recently bought a STAC zero and it happened on time that the chain got catched by the very strong magnets that thing uses to create resistance. That must be the reason. Can't wait to verify!

This is my problem as well.

My wife and I have the same bike (Specialized Diverge E5). In her bike, the speed sensor wasn't working properly on rear wheel. After some tests, I've found that in her bike, Garmin and speed weren't working correctly, but in my Diverge it was working properly with same Garmin config. The only difference between her and mine bike is the groupset: hers is Claris and the other is Sora. I've tested with other speed sensor and same issue happened in her bike. After moved the speed sensor to the front wheel on her bike, it started to work while on mine it works on both wheels.

My best bet is that the problem is in the cassette or in the chain - on some sort of interference.

0 Bike_John over 7 years ago

I have seen this once or twice since 5.0. And it only lasted for 10-20 seconds or so each time, that I noticed. I was going 17mph and the speed would go down to 6-8mph. I have my speed sensor around my front hub. It is the garmin no magnet sensor. I never had any issues before 5.0. It may have just been a fluke. 5.0 has been relatively pretty good for me so far.

I don't think this problem is restricted to just the Garmin speed sensors. I saw this same thing with a Bontrager Interchange speed/cadence sensor yesterday. The speed display would drop from 16 mph to 8 or 6 and back, then occasionally even to 2 mph or zero (which then caused auto-pause to kick in). I checked the calculated wheel size for the speed sensor but it was within spec. I disabled the ANT+ sensor pairing and re-paired via Bluetooth but the problem persisted or, if possible, got worse. Literally in the middle of nowhere, no power lines or other sources of electrical or magnetic interference. I wound up finishing the ride with the sensor disabled, and instead relied on GPS-based speed, the last ~75 miles without a cadence reading.

FWIW, I had seen this problem previously with an 820 I eventually returned (for this problem as well as the erratic touchscreen). I have video of the 820 periodically showing half speed or less while a 520 mounted right next to it displayed the correct speed.

0 6228927 over 5 years ago

I have a similar issue

I ride in Fulshear TX and I found that several other Garmin owners have also the same issue

I have a 1030, I use the sensor from Garmin in the back wheel. I have used in the front wheel and had the same issue.

we can clearly see where the speed goes crazy ( 10km/h 40km/h and then 23km/h in one second). It is clear that while we ride in a new concrete road it causes the issue. It may be because of the iron inside the concrete . I’m wondering if I get a Wahoo sensor it could fix this issue. By the way I use Wahoo cadence sensor and I do not see any kind of measurement problem.

0 danaurora over 5 years ago

I think its the new speed sensor that has the issue. It seems like most of us with the hub-style speed sensor show erratic speeds when going across metal bridges and roads reinforced with a lot of rebar in the concrete. I never recall having a problem with the spoke-magnet style sensor. I have the same problem on the stretch of road as 6228927 mentioned.

0 Rob W over 5 years ago

Recently started with Garmin and a Fenix 6X and a Speed Sensor v2 in Singapore. Started seeing massive speed spikes and a few drops outs.

Tried a reset and reconnect and the same issue.

Like others on here and other forums Im seeing these in similar places so it must be due to interference somehow. Disappointed considering the cost of them.