Results 1 to 8 of 8
  1. #1
    mtbr member
    Reputation:
    Join Date
    Mar 2013
    Posts
    65

    Bike computer calibration for 29er?

    Hey guys, I just got one of those wireless bike computers off eBay, the ones that are cheap as ****, it doesn't show a number for calibrating 29ers. This is the computer. New Sunding Sd-548c Multifunction Wireless Bicycle Stopwatch Odometer Speedometer Bike Cyclometers Waterproof Cycle Computer : Amazon.com : Sports & Outdoors

    and my bike is te gravity 29point3

  2. #2
    AZ
    AZ is offline
    banned
    Reputation: AZ's Avatar
    Join Date
    Apr 2009
    Posts
    19,998
    Measure the tire roll out and use the resultant number.

  3. #3
    human dehumidifier
    Reputation: wv_bob's Avatar
    Join Date
    Sep 2005
    Posts
    5,076
    Get a bit of grease or paint, and put a dot on the tire. Roll it along a paved surface, measure the distance between any two spots left on the ground from what you put on the tire.
    When you get older, much of your hate comes from knowledge and experience, which is why really old people hate everyone

  4. #4
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    4,211
    Just add 10% to everything.

  5. #5
    xc rider
    Reputation: e-kruger's Avatar
    Join Date
    Oct 2009
    Posts
    14
    No matter what tire and wheel size, or units (metric or british) use this method, that is most accurate:

    Put any value in your comp, let's say 2000mm. Ride one long straight distance that has some waypoints visible on google earth. Let's say you get 8400m.
    Measure the same distance on google earth - 9000m for example.
    If you can not find visible waypoints, use your gps and make them manualy (at the start and the end of ride) , then create them in google earth and measure the distance between those two.
    X is the value that you need to find and put in comp. (see graphics below)
    The longest and straightest the ride distance is - the more accurate wheel circumference you will get.



    Sent from my GT-P5100 using Tapatalk HD

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    8
    2288 for a 2.1 tire. 29er

  7. #7
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    183
    Just go by the stem - start with it at 6 o'clock and roll until it is at 6 o'clock again. The trick, though, is that you have to be on the bike, or your number will not be accurate (your weight squishes the tire, effectively making the circumference smaller). It helps to have another person help with the measuring. I just had to recalibrate my bike computer for my 29er, and I rolled along with one hand on my garage door. I put a tape measure on the ground and started with the stem at 0". My bike with 2.3" Bontragers worked out to exactly 90" or 2286mm for the tire circumference.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    1,167
    [QUOTE=SAWS;10442941]Just go by the stem - start with it at 6 o'clock and roll until it is at 6 o'clock again. The trick, though, is that you have to be on the bike, or your number will not be accurate (your weight squishes the tire, effectively making the circumference smaller). It helps to have another person help with the measuring. I just had to recalibrate my bike computer for my 29er, and I rolled along with one hand on my garage door. I put a tape measure on the ground and started with the stem at 0". My bike with 2.3" Bontragers worked out to exactly 90" or 2286mm for the tire circumference.[/QUOTe}

    And the difference between weighted and unweighted is quite large if one is looking for any kinda accuracy. I did it both ways once about 7 years ago..I'm sure it still stands now.
    lean forward

Similar Threads

  1. Best computer for my 29er?
    By Aquayonex in forum 29er Components
    Replies: 48
    Last Post: 09-24-2012, 03:05 PM
  2. Garmin Vs Bike Computer (computer more accuratte)?
    By Ilikejeeps2 in forum GPS, HRM and Bike Computer
    Replies: 13
    Last Post: 04-22-2012, 02:33 PM
  3. Shock pump calibration off?
    By khaytsus in forum Shocks and Suspension
    Replies: 5
    Last Post: 03-18-2012, 08:28 AM
  4. Powertap calibration reading on Garmin Edge
    By yampydog in forum GPS, HRM and Bike Computer
    Replies: 0
    Last Post: 12-04-2011, 01:36 PM
  5. Bell computer 29er setting?
    By AZJohnnyC in forum GPS, HRM and Bike Computer
    Replies: 5
    Last Post: 07-04-2011, 01:43 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •