Electronics, Lighting, & Gadgets - comp setup question

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adaminlc
02-02-09, 03:44 PM
This is just a random question, wondering if anybody knew. I had to do a hard reset on my cateye Astrale 8 today and had to reset the tire size. I realized that I have been running it at the setting for 700x 25 but I have been running 700 x 32 tires. The setting in the computer seems to be quite a bit different. Does the tire width make that big of a difference. I haven't noticed any difference in the distance that it registers on my normal rides. Is it all academic or could the different widths change how it registers? If it matters, both tires used are Bontrager Race Lite Hard Case tires.

thanks

jsharr
02-02-09, 04:03 PM
Larger Diameter tire will mean greater rollout for each revolution. Put something on your tire that will leave a mark (ink, chalk, etc.), get on your bike and with your normal weight on bars, roll forward. Now go and measure teh distance between marks in mm, and you have the number to use in your computer.
cyccommute
02-02-09, 05:26 PM
This is just a random question, wondering if anybody knew. I had to do a hard reset on my cateye Astrale 8 today and had to reset the tire size. I realized that I have been running it at the setting for 700x 25 but I have been running 700 x 32 tires. The setting in the computer seems to be quite a bit different. Does the tire width make that big of a difference. I haven't noticed any difference in the distance that it registers on my normal rides. Is it all academic or could the different widths change how it registers? If it matters, both tires used are Bontrager Race Lite Hard Case tires.

thanks

The difference in circumference is going to be about 2 cm per revolution. Not even enough to really worry about;)

twinquad
02-03-09, 09:42 AM
The difference in circumference is going to be about 2 cm per revolution. Not even enough to really worry about;)

So you could just program the computer with a number that's 2 cm larger than you had previously, which would give you a better estimate. This level of effort probably doesn't qualify as "worrying", whereas doing a roll test might. ;)
adaminlc
02-03-09, 04:32 PM
Thanks. I figured it must change the outside diameter of the tire a little.