installing lidl bike computer... setting up?

dcurzon
dcurzon Posts: 290
edited October 2010 in Commuting chat
so i've installed one of the budget lidl bike computers, and set the wheel circumference as per the instructions, but then it dawned on me...

surely that is only relevent given where on the forks/spokes the sensor is located?
ie. if the sensor is near the centre of the wheel, then the magnet will pass the sensor earlier than if the sensor is near the outside edge of the wheel.

or am i just not seeing it right??

i did a hand spin of the front wheel i the garage, and apparently it was doing 9mph. seems a bit wrong surely? i've located my sensors near to the rim.

can anyone confirm the circumference setting? 700x23c

thanks :)
B'Twin Sport 1
FCN 7 =4, +2(non cycling clothes) +1(beard)

Comments

  • UndercoverElephant
    UndercoverElephant Posts: 5,796
    The sensor counts the number of complete revolutions of the wheel. It doesn't matter where on the spoke the magnet is, it's still one whole revolution.

    Edit: The total circumference varies from tyre to tyre, even if they have the same number on the casing. Something in the region of 2120 mm, though.
    Sun - Rain - Snow
  • dcurzon
    dcurzon Posts: 290
    erm, yup, i guess that makes sense... the centre isnt rotating any faster or slower than the outside... d'oh!

    i think the instructions said 2124mm for 700x25, so thats what i used :)
    B'Twin Sport 1
    FCN 7 =4, +2(non cycling clothes) +1(beard)
  • Paul E
    Paul E Posts: 2,052
    dcurzon wrote:
    erm, yup, i guess that makes sense... the centre isnt rotating any faster or slower than the outside... d'oh!

    i think the instructions said 2124mm for 700x25, so thats what i used :)

    The outside of the wheel will be moving faster as it has to cover more distance than a rotation at the centre.

    Some people say mount the sensor lower so the sensor see's the mgent for longer but I prefer the top where there is less cabling to secore and never had any odd readings from my bike computer.
  • DCowling
    DCowling Posts: 769
    I thought the sensor needs to be within a certain distance of the magnet ( approx 5mm) so this will dictate where the sensor and magnet will be in relation to the rim.

    I also got the Lidl bike comp and have found the biggest pain is the visibility of the screen, it is almost set so it is tilting away from me, in order to see the display clearly

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