Related
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Reset tire size for new bike? Necessary?

Gary T.
over 3 years ago

Hi Everyone,

Picked up a new bike last week and went in to reset the tire size and it doesn't appear you can do that.  The distance was decently off from my Fitbit for my first ride, and they're generally pretty close.  Now I'll admit, I don't know if the actual wheel size/diameter changed.  I went from 700x23s to 700x32s.  Realizing it's the 700 piece that drives it, these tires are a bit thicker and I have to believe there's some small size difference.

I've put in about 200 miles on the new bike since I got it last week, and it seems after the first couple of rides the mileage is lining up again with my Fitbit, so I guess I'm ok.  Am I overthinking this?  What do others do - allow the auto configure, or measure the tire and enter it manually?

Thanks,

Gary

  • 0 over 3 years ago

    For myself, I see no reason to have any of this if it isn't accurate.  Auto configure just isn't likely to be as accurate as measuring yourself.  What I do, assuming you have a wheel speed sensor...

    1. Place a 25' measuring tape strung out on a flat driveway. 
    2. Line up the valve stem with the beginning of the tape. 
    3. Walk the bike, roll three revolutions directly beside the tape, not wavering.  For mtb, also pushing down on the bars to simulate rider weight makes even more accurate (actually makes a noticeable difference).
    4. Read length at end of three revolutions.
    5. Convert inches to mm (assuming you used an inch tape).
    6. Divide by three.  (The three revolutions is just a way to make more accurate; could use one, five or 1000...)
    7. You now have the circumference in mm.
    8. Enter this circumference number in the setup for the wheel speed sensor.  (Under options for the sensor, I believe.)

    If you do decide to use auto configure, you want a long straight path to ride without tree cover or it won't be at all accurate.

  • 0 over 3 years ago

    At the bottom of the edge manual contained in the package, you will find a table with tire size and relative number to enter, I did this and it works, I went from 700x32 to 700x28

  • 0 over 3 years ago in reply to Cranky K.
    Cranky K. said:
    If you do decide to use auto configure, you want a long straight path to ride without tree cover or it won't be at all accurate.

    How would I do that though?  I don't see a way to tell it to remeasure.  

    When I first got it I paired it with my speed and cadence sensors and then hopped on.  About a half a mile in a message popped up telling me it had set a tire diameter.  I noted initially it seemed a to be a bit high, but settled down after a couple rides.  After putting the device on my new bike I saw the same thing - first two rides seemed a bit high, and then it started to appear accurate.

    I'm not opposed to measuring and entering it manually - but I'd like to force the auto configure if possible and compare it to what I measure as a bit of a test. 

    It appears from the two responses I've gotten folks prefer to enter it manually.

    Thanks,

    Gary

  • +1 over 3 years ago in reply to Gary T.

    If you want to recalibrate, then go to settings and delete(remove) the speed sensor.  After you delete the Speed sensor, then add it.  It will autocalibrate itself when you start your ride. 

  • 0 over 3 years ago in reply to Jordan249

    Delete and re-add the speed sensor, but do the roll-out measure I described and add the circumference manually.  By far the most accurate way and the whole process takes less than 15 minutes.  The tire charts aren't nearly as accurate as measuring yourself as tires vary by manufacturer. 

  • 0 over 3 years ago in reply to Cranky K.

    If you have it set to automatic it is continuously re-calculating the wheel size using a slow moving average.

  • 0 over 3 years ago in reply to aweatherall

    But this leads to much less accuracy, as all GPS will cut corners off since it isn't pinging constantly.  I find this is especially true with mountain biking, as we have lots of switchbacks.  Tree cover further complicates.  Roll-out, measure, input manually, very accurate for every ride.

  • 0 over 3 years ago in reply to Cranky K.

    I found the Auto Configuration less then accurate and did as Cranky K described.

  • 0 over 3 years ago in reply to WalterB

    Personally I manually set the wheel size. I was just explaining that the auto is not a one an done, but rather a continuous process. 

  • 0 over 3 years ago in reply to aweatherall

    @aweatherall   Ok, even though I manually set circumference, that it good and interesting to know.  Thanks for the info.

    This means, that even if you use Auto Config on a perfectly straight course with no tree cover you will eventually end up with a device that is not accurate if you ride with lots of turns. 

    I know I'm a bit insistent on this, but I just want to encourage others to manually measure and enter the circumference.  It's just so easy to make very accurate in 10 minutes, I don't know why anyone wouldn't do it this way.

    And now as fall approaches I'm waiting anxiously for cold weather to see how the 130 performs with FW3.70... I'll be watching those battery life threads to compare notes.