Fenix 5 and speed/cadence sensors

If I use speed sensor on my bike will it override gps data regarding speed, distance, etc? If I set wheelsize to auto on my F5 will it then use gps distance and rpm to calculate wheelsize?
Went for a 55km ride today and GC show 13km. This was the first time I used speed sensor on my bike here in Thailand. Usually I use it on my outdoor and indoor bike in Norway, so wheelsize was totally off. Is there any point at all using speed sensor when F5 has gps? Accuracy sensor vs gps?

0 Dr Phil over 7 years ago

Set speed manually when you have a speed sensor mounted. Since the auto setting requires a good GPS signal to work out the wheel size, it's prone to inaccuracy. Also make sure your magnet (if it a sensor with a magnet) is properly positioned.

0 Former Member over 7 years ago

Have a look at your speed and candence graphs
I’d like to bet there’s loads of drop outs which would explain your short reported distance

my previous F5 was atrocious with my speed and cadence sensor but the replacement I have is pretty good

0 Bekkedalen over 7 years ago

Set speed manually when you have a speed sensor mounted. Since the auto setting requires a good GPS signal to work out the wheel size, it's prone to inaccuracy. Also make sure your magnet (if it a sensor with a magnet) is properly positioned.

But is there any advantage in using speed sensor i stead of just using watch gps? Back home in Norway I have used speed and cadence sensor but never thought about accuracy sensor vs gps.
What is best?

0 Bekkedalen over 7 years ago

Have a look at your speed and candence graphs
I’d like to bet there’s loads of drop outs which would explain your short reported distance

my previous F5 was atrocious with my speed and cadence sensor but the replacement I have is pretty good

The reason for the short reported distance is that F5 was calibrated for indoor biking prior to this run. I forgot to readjust after mounting on outdoor bike.
Thats why I was wondering if wheel size set to auto will measure correct wheel size or if it would be better to manually set size. But thank you for your suggestion.

0 Drew over 4 years ago in reply to Bekkedalen

questioning the same with self having the following equipment to share on 3 bikes:

Kinetic Kurt stationary trainer with integral power and speed sensors

Garmin Fenix 5 watch

Garmin 1030 Edge Plus

2 sets of Garmin sensors (speed + cadence)

So how does it play out in my stable? what is my best use of sensors?

Stationary trainer - its integral power and speed sensors are sufficient and cadence not much of a concern as I ride consistently at 90rpm over the years.

A-bike (Pinarello FP Quattro) - (speed + cadence) sensors paired to Fenix 5 or Garmin Edge. Rational = nbr 1 ride, most use, ground based speed signal delay less than that of space (SAT) based speed computation & cadence always important for road hammering

B-bike (rain bike, DEAN Colonel) - cadence sensor paired to Fenix 5 or Garmin Edge. Rational = cadence on road bike more important than on MTB and can live with space based speed data from Fenix or Edge in suburban environment for the infrequently ridden rain bike

MTB (ORBEA OCCAM) - speed sensor paired to Fenix 5 or Garmin Edge. Rational = SAT based speed data signals often interrupted in heavy PacNW forests or when behind/under large boulders or steep terrain => therefore SAT speed data can be intermittent... AND cadence not so important on MTB... in fact, don't tell anyone I said this but I sometimes encounter terrain in the woods that forces me to get off the bike and walk... and its probably not even that steep. geezus, can't believe I just admitted that. :)