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  • How can a bike computer add mileage with a broken cable?
  • JoeG
    Free Member

    Yesterday, I had a nice crash (front wheel slipped out on wet leaves!) and I’m fine. Only damage to the bike was the wire for my bike computer broke. It was completely cut in two, and the loose ends hang 6 to 8 inches apart on the bike.

    The computer is a Sigma Sport 1009 with a conventional wired mounting; magnet on the spoke, sensor on the fork lower, wire to the computer on the handlebar. No cadence sensor or anything like that.

    Obviously, the crash was Satan’s fault as it occurred at a trip mileage of 6.66 miles which was pretty easy to remember.

    So, how on earth did my mileage go up to 6.72 miles by the time I got back to the parking lot? 😯

    d4
    Free Member

    Both ends touching the frame intermitently?

    stumpyjon
    Full Member

    Wires shorting? Not related but one of my wireless computers once hit 200mph on my Mother in Laws sideboard, never did work out what caused it, only happened in one specific place as well.

    wobbliscott
    Free Member

    I’m only guessing but as the sensor only measures once per rev, which is not very frequent or accurate for a real time sample of speed at any time, there is bound to be some form of buffering that lags slightly behind real time to smooth out the input signal, so if you look at the mileage immediately as you stop, the buffering may not have fully washed out as the computer may bot have sussed out that you’ve actually stopped, and in the following few seconds the mileage is adjusted to a more accurate reading. As I said, only a guess, but there must be some form of smoothing of the input signal.

    JoeG
    Free Member

    Both ends touching the frame intermitently?

    I don’t think so; the upper wire stuck straight out (horizontal) away from the bike and the lower wire was almost vertical.

    [/quote]Wires shorting?

    Bike was dry, ends of the wire were far apart. The ends were nowhere near the frame, which is bare Ti.

    wobliscott – I agree on the sampling, buffer, etc. But it was a good minute or two from when the crash happened to when I checked the mileage. I got up, checked the bar alignment, brakes, chain, saddle and such before I noticed the broken wire.

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