Garmin Edge

essex-commuter

Why would you use a speed sensor for speed and distance and not just the GPS unit?

I never used one on my old Garmin but my new 800 came with one and I'm wondering what the advantage is apart from cadence.

monkimark

I think the short answer is that it gives a more accurate speed reading when the gps signal is poor.

slowbike

It smooths out the speed data - GPS is OK, but can go wildly wrong.

eg
1) I'm sat beside my wife on a gradient with overhanging trees. We're travelling at ~8mph according to my 800 with speed/cadence. Her 810 (with no speed as the magnet is in the wrong place) goes into auto-pause.
2) I'm cruising on my tricross (no speed/cadence) - just a steady ride on a country road - the speed display is up and down all over the place +/- 3mph despite the fact that I've not changed gear and my cadence is steady.

drlodge

monkimark wrote:

I think the short answer is that it gives a more accurate speed reading when the gps signal is poor.

This ---^ but only in real time on your device. I've just revomed my GCS10s since I don't bother with cadence anymore and speed comes with GPS, and the GSC10s were cluttering up my bikes. Speed does fluctuate under tree cover, and the gradient indicator then disappears too.

meanredspider

Yup - otherwise going through an underpass can give a speed spike etc

essex-commuter

Thanks guys. Been pretty happy not having one so will probably not use it...might be good for the turbo though....I presume?

I've been cycling long enough to know my cadence without having it measured.

slowbike

drlodge wrote:

monkimark wrote:

I think the short answer is that it gives a more accurate speed reading when the gps signal is poor.

This ---^ but only in real time on your device.

and it stores it in the FIT file ...

Just a quick crude analysis of two rides on Strava - the one without the speed/cadence sensor is more spikey in the speed readings compared to the one with.

pblakeney

There are two reasons as to why I use the magnet sensor along with my 705.

1. Turbo sesions.
2. Tunnels.

For the sake of adding a small magnet I cannot see why not.

drlodge

PBlakeney wrote:

There are two reasons as to why I use the magnet sensor along with my 705.

1. Turbo sesions.
2. Tunnels.

For the sake of adding a small magnet I cannot see why not.

Cos you also have to fit a chuncky sensor unit to the chainstay too? :roll:

pblakeney

drlodge wrote:

PBlakeney wrote:

There are two reasons as to why I use the magnet sensor along with my 705.

1. Turbo sesions.
2. Tunnels.

For the sake of adding a small magnet I cannot see why not.

Cos you also have to fit a chuncky sensor unit to the chainstay too? :roll:

I already have that for cadence.
Here is a :roll: just for you.

ddraver

Absolutely the main reason to use it is for turbo training...

I find having cadence quite useful to try and "unfixie" myself, not sure knowing my speed to 0.1kph makes much of a difference (I don't notice it on the MTB where I ve not got one). However I have to say that I ve never yet seen my Garmin register a speed of 0.0kph using GPS alone ever - it always hovers between 0.3 - 0.8kph when I'm standing still