Garmin wheel circumferences

[awesme]

Hi all

 

What do you have set as your wheel circumference for:

 

26er with 2.2 tyre

I got 2053 (Tyre pressure of 1.8)

 

27.5 with 2.25 tyre.

2128 (Tyre pressure of 1.8)

 

G

[Tankman]

Why do you want to use it?

 

GPS!! Does all that for you!

 

Remove that speed magnet immediately and only use when on the IDT

[TopFuel]

G, have a look in the manual. I'm pretty sure I saw values in the Edge 500 manual.

 

Tank, why not both? Properly measured wheelsize will be far more accurate that GPS?

[awesme]

I've found that a table is just "close" values.

 

You will even have different measurements for being on the bike or off, and dif values with a proper inflated tyre or not.

 

G

 

G, have a look in the manual. I'm pretty sure I saw values in the Edge 500 manual.

 

Tank, why not both? Properly measured wheelsize will be far more accurate that GPS?

[TopFuel]

I've found that a table is just "close" values.

 

You will even have different measurements for being on the bike or off, and dif values with a proper inflated tyre or not.

 

G

 

Ah yes, I had a look in the manual myself, only 2.1 or 2.35. That being said, my 2.1 is 2068 (26"), so surely yours should be more than 2053? Did you measure manually?

[NotSoBigBen]

Garmin has that 'auto' wheel size feature. I use that. No good indoors though .....

[Thor Buttox]

G, have a look in the manual. I'm pretty sure I saw values in the Edge 500 manual.

 

Tank, why not both? Properly measured wheelsize will be far more accurate that GPS?

I tried entering the numbers from my last computer into my Garmin and it was a disaster. It kept saying I was doing 60kph on my road bike for some reason. I found the GPS is very accurate and I don't have to worry between switching between bikes either.

[Helpmytrap]

Garmin has that 'auto' wheel size feature. I use that. No good indoors though .....

When I'm indoors I switch the gps function off for the IDT, the Garmin then uses the data from the speed sensor. Not that it is relative since it varies depending on the amount of resistance you initially put on the tyre.

[awesme]

The 2068 will be without a rider on the bike, probably measured around.

 

What I did is put my wife on her bike, rode a full circle, and then measured the distance travelled.

 

G

 

Ah yes, I had a look in the manual myself, only 2.1 or 2.35. That being said, my 2.1 is 2068 (26"), so surely yours should be more than 2053? Did you measure manually?

[Dicky DQ]

"When I'm indoors I switch the gps function off for the IDT, the Garmin then uses the data from the speed sensor. Not that it is relative since it varies depending on the amount of resistance you initially put on the tyre."

 

 

How so? Sorry may be a stupid question....

[TopFuel]

Hold menu, select GPS, select GPS status, Set enabled = no, press back and you're done. Same process to turn it back on, but set enabled = yes.

 

Edit: or just turn it off and on, and it'll sort itself out!

Edited June 26, 2013 by TopFuel

[akneethling]

Pretty simple. I use a radius measurement, measure from the center of the axle to the outside of the tyre. Then use this formula below for the most accurate measurement.

 

2×pi×radius = circumference

 

Pi = 22/7 but most calculators will have pi. Its the T with the extra leg.

[akneethling]

But I agree with tankman. You should only use it when on an IDT. Then super accurate distance is not a requirement

[awesme]

Akneethling

The radius idea works, same as measuring with tape measurement, but now take that measurement and compare it with a weighted run of one rotation.

 

As for GPS, it's only very accurate if you riding flat level, once you start climbing and descending you loose distance. GPS does not account for nicking and descends

 

G

[akneethling]

Akneethling

The radius idea works, same as measuring with tape measurement, but now take that measurement and compare it with a weighted run of one rotation.

 

As for GPS, it's only very accurate if you riding flat level, once you start climbing and descending you loose distance. GPS does not account for nicking and descends

 

G

Ok. I find GPS pretty accurate though. Ascent and descent included. But to each his own if you feel like it. Glad the radius idea worked. High School math. Its a bit easier than rolling a wheel 1 revolution, then measuring the distance. It's quicker and more accurate.

[Guest Smimby]

Garmin has that 'auto' wheel size feature. I use that. No good indoors though .....

The idea is that you set it to auto and go for a ride. Garmin will calculate wheel size fir you that you can then enter.

 

Now take the magnet of again and ride, outside it will use GPS and when you on the idt put the magnet on.

 

Just a note. If you have a magnet on and entered a wheel size garmin will use that and NOT the GPS to calculate speed and distance. GOS is them only used to track your route/course