Issues cycling with the Garmin Speed & Cadance Sensor

Former Member over 7 years ago

Hi there,

I've only had my fenix 5 for less than a week so I may be doing something daft but I thought I'd ask the questions anyways.

I paired up the garmin speed/cadence sensor that I already had from my old fenix 2. All seemed fine, however I forgot to put in the wheel size manually and left it on auto.

The first ride was my commute to work, so the results where slightly higher than usual. Over the 18km I think I was showing 1km more than the actual distance travelled.

So I then went and set the wheel size manually for my tyre size. Repeated the same journey in reverse and now my18km journey came up as 33km on my watch. However the gps tracking on the map once I had synced it to my phone was perfectly correct. So the gps had tracked accurately but the speed/cadence sensor is now miles off.

I'm riding 700*23 tyre size and have used the 2096mm wheel size on my settings as per the guide.

Any ideas where I am going wrong?

Thanks
Kirit

0 mcalista over 7 years ago

2096 seems slightly too high for a 700x23 tyre. But actual tyre sizes can differ significantly between manufacturers, despite being nominally 23mm, so you should ignore the manual anyway. Measure the ACTUAL rollout (valve at the bottom to valve at the bottom), and then use that figure.

The auto calibration needs a clear and open view of the sky to work properly.

0 Former Member over 7 years ago

I did the same commute again this morning. Wearing both my Fenix 5 connected to the speed/cadence senor and also my Fenix 2 without any speed sensor connected.

This time Fenix 5 showed 38km v's the Fenix 2's 19km (the Fenix 2 was spot on correct by the way, I've been doing this commute for years)

I understand the 23mm measurement can't vary from brand to brand, but I find it hard to believe that one brands 23mm would be almost twice the actual size of another brands 23mm? but I guess anything is possible.

Anyhow I had been using the same bike, wheels & tyres, spd/cadence sensor with my Fenix 2 previously and that never had any problems. I should also add I manually set the size on my Fenix 2 to the same 2096 size I'm using with the Fenix 5.

I will try measure my the wheels manually tonight, but that 2096 measurement worked perfectly on the old fenix 2 so I doubt this will be significantly different to the actual measurement.

0 tmk2 over 7 years ago

What type of sensor are you using? Is it the new magnetless sensor or the old speed/cadence combo sensor (GSC-10)?

Check out this discussion:
https://forums.garmin.com/forum/into-sports/cycling/edge-500/27179-inaccurate-speed

0 Former Member over 7 years ago

Yes it is the old sensor with the magnets.... thank you for that link I reckon I have the same issues.

I just looked at the settings on my fenix 2 and it looks like I had the "bike speed" set to "indoors". So looks like I was never reading speed/distance from the sensor on my old watch, hence I never noticed the issue in the past.

I will check how the sensor is set up tonight, see if I can make sense of it - thanks again for you help!!