Garmin Settings

[BrianC]

Sorry i just cant find the answer for this and it may be a stupid question. On my road bike i was using 700x23c tyres i've recently changed to 700x25c tyres. Now as you know on the unit you can change the wheel setting from auto to manual. Should i be changing it to suit the 25c or leave as the 23c

 

[young Ed]

what model of device? not a clue sorry, on my edge touring i don't think it has any of this
Cheers Ed

 

[cosmicbike]

If you have a speed/cadence sensor it will adjust itself. If you don't then tyre size is irrelevant since speed and distance are dealt with by GPS

 

[MickeyBlueEyes]

The 23 and 25 are only referring to the width of your tyres and therefore should have no bearing on the units calculations.
Unless there is a massive difference in sidewall depth I wouldn't change it.

 

[BSRU]

Sorry i just cant find the answer for this and it may be a stupid question. On my road bike i was using 700x23c tyres i've recently changed to 700x25c tyres. Now as you know on the unit you can change the wheel setting from auto to manual. Should i be changing it to suit the 25c or leave as the 23c

You should adjust the manual setting to reflect the circumference of your new tyre, if you've bought Continental tyres they often have that information on the box.
I used to use "Auto" mode but it can be widely wrong resulting in different distances for the same ride.

 

[w00hoo_kent]

A bit confused, presuming the Garmin is a GPS why should it care? My Touring+ has no bike related settings that I've seen. Even one with a cadence sensor is counting pedal strokes and nothing else. All of the distance and speed calculations are being done by position relative to satellites surely?

 

[BSRU]

A bit confused, presuming the Garmin is a GPS why should it care? My Touring+ has no bike related settings that I've seen. Even one with a cadence sensor is counting pedal strokes and nothing else. All of the distance and speed calculations are being done by position relative to satellites surely?

The Edge GPS units are not as accurate as some of the touring units as they use GLONASS as well as GPS to get a far more accurate position.

 

[morrisman]

A bit confused, presuming the Garmin is a GPS why should it care? My Touring+ has no bike related settings that I've seen. Even one with a cadence sensor is counting pedal strokes and nothing else. All of the distance and speed calculations are being done by position relative to satellites surely?

If you have a Garmin that will accept a speed and cadence sensor the GPS speed is not used as the wheel sensor, assuming it is correctly set up, is far more accurate. For example I fitted my speed and cadence sensor once the summer had arrived as the increasing leaf coverage was causing the speed to read low when on GPS.

 

[Nigelnaturist]

@morrisman the Touring doesn't have Ant+
@MickeyBlueEyes it makes a significant amount of change over some distance, nominal size is 2098mm for a 23mm tyre and 2111 for a 25mm tyre or 13mm for each rotation of the wheel about 0.006% or 620m over a 100Km (bit of a pisser doing all that only to find you were 1/2Km short) and a small but significant difference in speed, have used a Rider 20 and an edge 705 one set to 2098mm and one to 2111mm if on 23mm the one on 2011 would show you going faster than you are and vice-versa.

 

[maltloaf]

As I understand it from reading a post on the Garmin forums, the speed sensor doesn't have anything to do with the distance recorded. That all comes from GPS.

The speed sensor improves the displayed and recorded speed information and reacts more quickly to significant changes in speed, such as starting a descent or climb. Without it there is a slop period. With it it's instantaneous. I can confirm riding with and without one on the same route has no effect on distance but without it the data is much less smooth.

 

[BSRU]

As I understand it from reading a post on the Garmin forums, the speed sensor doesn't have anything to do with the distance recorded. That all comes from GPS.

That makes no sense, if I set it to a different wheel size the distance I cycled on the same route changes.

 

[T.M.H.N.E.T]

As I understand it from reading a post on the Garmin forums, the speed sensor doesn't have anything to do with the distance recorded. That all comes from GPS.

The speed sensor improves the displayed and recorded speed information and reacts more quickly to significant changes in speed, such as starting a descent or climb. Without it there is a slop period. With it it's instantaneous. I can confirm riding with and without one on the same route has no effect on distance but without it the data is much less smooth.

Spin your wheel. It will record distance without the bike moving. The same concept(and turning gps off) allows use on turbo trainers.

ps: where sensor hardware is fitted and functioning, garmin units will by preference take information broadcast by them first.

 

[maltloaf]

This is true actually thinking about it as that's what happens on the turbo but the post I read said distance comes first from GPS if GPS data is available and is smoothed by the speed sensor. I have never ridden with it set to anything other than auto tho so can't comment on changing setting changing distance recorded. The smoothing/reactivity aspect with sensor vs without certainly is true though.

I will have a search for the post I'm referring to and hopefully that will make more sense..

 

[T.M.H.N.E.T]

Garmin state in their own FAQ that information from hardware is preferenced over GPS.

re:smoothing. I've noticed that when riding bikes without sensors (ie: MTB)

 

[maltloaf]

I wonder what the result would be if you were being driven around in a van recording the route but spinning the wheel. Would the distance be the distance travelled or the distance spun ? I might do this experiment :-)