Topeak computer conundrum

pinno
pinno Posts: 52,639
edited September 2012 in Workshop
Just replaced the battery on my cheapy Topeak computer and I do not know what the calibration number for the thing is. If you own a Topeak and you actually kept the instruction/fitting booklet unlike me, please tell me what the calibration number is for a 700x23 and a 700x25c tyre. Ta.
I used a Blackburn chart 'measure the rolling distance' and came up with an entry of 2105. I was very happy cycling along at an average 28mph but unfortunately the suspension of reality has to stop. :(
seanoconn - gruagach craic!

Comments

  • mike23864
    mike23864 Posts: 54
    This any good?
    http://www.bikearoundlongisland.com/Com ... nChart.htm
  • arthur_scrimshaw
    arthur_scrimshaw Posts: 2,596
    can you not do the rolling tyre test? chalk mark on the tyre and path, get on it and ride slowly counting the revolutions (much easier with a helper) then measure the distance and divide by the number of revolutions.
  • keef66
    keef66 Posts: 13,123
    Arthur Scrimshaw wrote:
    can you not do the rolling tyre test? chalk mark on the tyre and path, get on it and ride slowly counting the revolutions (much easier with a helper) then measure the distance and divide by the number of revolutions.

    I think he already effectively did this via the Blackburn chart. Unfortunately the computer appears to need a different number. My Halfords computer is the same; it seems to require a number that isn't the circumference of the inflated tyre (???) but fortunately I kept the instructions
  • keef66
    keef66 Posts: 13,123
    http://www.topeak.com/mediafiles/assets/583/file/1

    according to that 23c = 2132
    and 25c = 2146
  • pinno
    pinno Posts: 52,639
    Thanks Keef 66. Have not perused the web site, I will enter the figures and chase trucks. When the truck gets to 56mph, I will see if my computer is near enough :D

    Yep, did all that rolling/measuring thingy - was way off.
    seanoconn - gruagach craic!
  • eddieodea
    eddieodea Posts: 2
    All of our manuals are on the Topeak.com site. Start here: http://www.topeak.com/products/Computers then select the model you have and look to the right of that page. There should be a box to the right titled "Downloads"....find the appropriate language and you'll have all the info you need.

    Eddie O
  • pinno
    pinno Posts: 52,639
    Hello - somebody left the lights on!

    Thanks steady eddie, but keef66 solved the problem for me, though I will check the site out.
    seanoconn - gruagach craic!

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