# Computer Calibration Question

Discussion in 'Road Cycling' started by Birke D, May 3, 2003.

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1. ### Birke D Guest

The distance measurement readout on my bike computer is close, but slightly less than true distance
traveled. For example, if I rode 10 miles, the computer reading would only be 9.8 miles. The tires
are fully inflated so it's a question of the computer setting. Before I really screw up the
settings, do I need to increase or decrease the computer wheel size reference number? Thanks in

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2. ### Gary German Guest

"Birke D" <[email protected]> wrote in message news:[email protected]...
> The distance measurement readout on my bike computer is close, but
slightly
> less than true distance traveled. For example, if I rode 10 miles, the
computer
> reading would only be 9.8 miles. The tires are fully inflated so it's a question of the computer
> setting. Before I really screw up the settings,
do I
> need to increase or decrease the computer wheel size reference number?
Thanks

Increase.

3. ### Chris Freeman Guest

How do you know your cycle-computer isn't correct? What are you measuring the supposed 10 mile
distance with?

Chris

Birke D wrote:

> The distance measurement readout on my bike computer is close, but slightly less than true
> distance traveled. For example, if I rode 10 miles, the computer reading would only be 9.8 miles.
> The tires are fully inflated so it's a question of the computer setting. Before I really screw up
> the settings, do I need to increase or decrease the computer wheel size reference number? Thanks

4. ### Birke D Guest

> The distance measurement readout on my bike computer is close, but slightly
>> less than true distance traveled. For example, if I rode 10 miles, the
>computer
>> reading would only be 9.8 miles.

That was just a hypothetical example used to clarify my inquiry. I've done many rides over different
measured distances and I always come up a little short on my computer.

5. ### ØYvind RøTvold Guest

[email protected] (Birke D) writes:

> The distance measurement readout on my bike computer is close, but slightly less than true
> distance traveled. For example, if I rode 10 miles, the computer reading would only be 9.8 miles.
> The tires are fully inflated so it's a question of the computer setting. Before I really screw up
> the settings, do I need to increase or decrease the computer wheel size reference number? Thanks

Increase, by appr. 2%, probably around 4cm.

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6. ### Pete Hickey Guest

In article <[email protected]>, Birke D <[email protected]> wrote:
>> The distance measurement readout on my bike computer is close, but slightly
>>> less than true distance traveled. For example, if I rode 10 miles, the
>>computer
>>> reading would only be 9.8 miles.
>
>That was just a hypothetical example used to clarify my inquiry. I've done many rides over
>different measured distances and I always come up a little short on my computer.

How do you know the *real* distance? Bicycle computer's can be very accurate.

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