pcmike

I just put Conti Top Touring 2000 tires on my Bianchi Axis. My Cat Eye Double Wireless was set up by my lbs for 700 x 350 tires.
The new ones are 28 X 1 3/8 X 1 5/8.
As I convert that into mm it works out to something like 711.2/35/41/2mm
My question: Do I have to change the Cat Eye Double Wireless? How far off would my mileage be? Is that (700 as it's set now for the previous tires versus 711 with the new Conti's) a sigificant number or can I be reasonably sure the 25 miles registered for my daily ride is accurate?
I looked in the manual and couldn't find any setting for my new tires or exactly how to do an escat meadsurement.
Thanks!

'nother

The most accurate way is to do an actual rollout test with the tires inflated to the normal pressure you'd ride on, and with you in the saddle. Get someone to help, mark with chalk or whatever on the sidewalk, and roll out one complete revolution (or two) and measure the distance between marks. Use the valve stem as a reference (obviously: divide by 2 if you do 2 revs!). That'll get you the true circumference, which will likely be different than what the charts tell you (though still usually pretty close).

You should change this every time you change brands of tires because they are different, and it will affect calculations of speed, distance, etc. etc. In your manual, you want to look for how to enter the wheel circumference.