Cateye Astrale 8 - first impressions

the black rose wrote:

Heh. I recently rode that rail-trail I've been avoiding, to see if my
bike computer was calibrated anywhere near reality, on the theory that
the mileage markings on the rail-trail are reasonably close to accurate.
I started with my front hub directly over the start line, rode slowly,
and stopped with my front hub directly over the 1 mi line.

It sort of bothers me that the circumference value in the charts never
quite matches my manual measurement; and how or why the various MTB
widths result in a different *circumference* (e.g. 26x1.75, x1.95,
x2.1 etc).

I've had the chance to check the 'puter against automated radar speed
things("Speed Limit XX - Your Speed YY") and all three times the
'puter was dead on with the display. For the speed to be right, both
the circumference entry and the 'puter timer has to be right or very
close.