Garmins' new speed & cadence sensors

Jules Winnfield

I've just ordered a set of these from Wiggle and I was going to primarily use them for when I'm on the turbo trainer. But considering they are supposed to be fit and forget, I was just wondering what the hassle would be in having my 510 pick both sensors up, even when I'm out on the road.

I cant see any problems with the cadence sensor, in time a cadence reading when I'm out on the road riding might become invaluable. Im a bit more concerned about the speed sensor though. From what I gather, the Garmin will take preference for speed/distance over the GPS on the Garmin.

Would this give conflicting results and mess up my distance travelled?

Or to save any confusion, would it be best to just fit the speed sensor to the rear hub and just disable it on the Garmin when I'm out on the road and just enable it again when I'm on the turbo trainer?

Bar Shaker

The Garmin will calibrate the speed sensor to high accuracy before it starts displaying any wheel rotation derived speed data.

My own repeatable experience shows that the speed sensor lets the head unit display wheel speed only if it loses satellite signal to a level that means it cannot accurately display your current GPS derived speed.

The data file that the Garmin creates records speed to 8 decimal places. If it was doing this from a speed sensor, it would be measuring wheel rotation to an accuracy of the width of a hydrogen atom. Some people will argue it is doing this.

chris_bass

don't want to go over old ground but in my experience the speed sensor is always used regardless of GPS signal if the sensor is detected.
to avoid the same as last time happening many posts saying this is true/false can be found here:

viewtopic.php?f=40013&t=12979792&p=19017675#p19017675

if you set the unit to auto calculate the wheel size you should get a more accurate distance and speed reading so no need to disable it on the road.

BrandonA

Chris Bass wrote:

don't want to go over old ground but in my experience the speed sensor is always used regardless of GPS signal if the sensor is detected.
to avoid the same as last time happening many posts saying this is true/false can be found here:

viewtopic.php?f=40013&t=12979792&p=19017675#p19017675

if you set the unit to auto calculate the wheel size you should get a more accurate distance and speed reading so no need to disable it on the road.

This was my understanding too.

Jules Winnfield

Cheers Chris for the link, very informative thread.

ben@31

In the settings menu you can also add the wheel size manually. For example 700cx23.

I could never get my head around if where you place the magnet along the spoke makes any difference? Does the different ends of a spoke take the same time to rotate through 360 degrees or does the hub take less time / move slower than the rim? If someone could explain this to me Id be greatfull

Initialised

I could never get my head around if where you place the magnet along the spoke makes any difference?

One rotation is one rotation, if the wheel has a 2m circumference the bike will travel 2m per rotation of the wheel regardless of the position of the sensor relative to the centre of the wheel.

wongataa

ben@31 wrote:

In the settings menu you can also add the wheel size manually. For example 700cx23.

I could never get my head around if where you place the magnet along the spoke makes any difference? Does the different ends of a spoke take the same time to rotate through 360 degrees or does the hub take less time / move slower than the rim? If someone could explain this to me Id be greatfull

Every part of the wheel has the same rotational speed so it doesn't matter where on a spoke a speed sensor is placed. If one end of a spoke took a different time to complete a rotation than the other end the spokes would not stay straight.

Jules Winnfield

It makes no difference where the magnet is placed, im talking about the new speed and cadence sensors here that are totally magnetless.

Anyway, they came today and they are so easy to fit and get paired to my Garmin 510. In total it took about 5 minutes with no hassles. I then took the bike out for a ride and within half a mile a message popped up on the Garmin..... "Wheel size calibrated". So the default setting on the 510 must be 'Auto' cos i didnt change anything in the settings menu.

keith57

I read in another thread that the cadence sensor should work if you attach it to you shoe. I might try this to see if it works, can't see why not. I would only need one then! Not one for each bike.

davidof

What did you pay for them?

You know you can get the Decathlon ANT+ speed and cadence sensor for 17 quid.

Jules Winnfield

Yes but I wanted the new Garmin ones and besides, the Decathlon ones look cheap. I paid £49 for the Garmin ones BTW. No hobo here

Mikey23

Six months on and still chuffed with the new kit

Jules Winnfield

Mikey, because you have had more experience of them, how do they fare in the wet weather? Have you had any problems?

Bar Shaker

Mine got thorough soaked in the New Forest on Sunday. Not problems at all.

I have my speed sensor on the front wheel, it seemed more sensible having it closer to the head unit and away from my EWW01.

Mikey23

@jules... Never really had a prob with the old gsc10 which worked faultlessly throughout last winter. I just thought it looked a bit heath robinson and because the chainstays on my roubaix slope inwards, it had to stick upwards. I didnt kick it into the wheel but alwaysfelt that i might. The new one, clipping simply around the wheelhub looks and feels much more robust. And is easily transferable. Has been out a few times in the rain.

One issue i have noticed on my regular routes is that it causes an autopause in two particular places on hills even though my 500 is set to stop only and im still going relatively fast. Also it went a bit bonkers on ride london turning on/off about 30 times in a row after the tunnel. I suspect that this might be a software compatibilty issue that garmin havent addressed yet. Come to think of it, it was a bit wet that day!!!