Re: New Computer Installation

nobody@xxxxxxxx says...
I have recently purchased a new CatEye computer for my bike. In the past
the computer that I have installed stated in the instructions that the
magnet should be placed as close to the axle as possible. With my new
computer the sensor/magnet is placed about midway on the fork. Nothing
in the instructions state how high or low on the fork the sensor should
go. If the sensor is placed at a random height, won't this throw off the
accuracy of the computer? If the magnet is not placed as close to the
axle as possible, won't this throw off the balance of the wheel?
One wheel revolution is still one wheel revolution no matter where the
sensor and magnet are. However, the placement of the sensor/magnet has
nothing to do with accuracy, but with how fast the magnet passes the
sensor. If the magnet passes the sensor too quickly, it may not have time
to register. That's why most instructions I have seen recommend placing
the sensor lower on the fork and closer to the hub.

I have used Cateye and Planet Bike computers and both of them work over a
fairly wide range of positions. The Cateye magnet is very small and
light. I even bought spares for my Planet Bike computers for that reason.
Bike wheels don't spin fast enough for wheel balance to be much of a
problem.

Barnard Frederick [Yme ] wrote: So the computer sensor counts the number of revolutions, this along
with the wheel size is used to determine the distance traveled.
This is similar to how a pedometer works. How does the computer
determine the speed? I would assume how frequent the magnet passes the sensor. The speedometer would indicate a faster speed when sensor is closer to the axle, than when the sensor is faster away from the axle. It seems if the sensor is an inch too high or too low on the fork the speedometer would be off by less the 1 mile per hour probably less.
This make sense now thanks for everyones explanation.

The sensor increments "one iteration" to the chip- it matters not where the magnet is placed, it's still "one iteration". The chip has a crystal clock and a factor for wheel travel. That number may be adjusted to the actual travel of your wheel with you on your actual bike.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
.

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