Bicycle Mechanics - Help reset tire size on bike PC

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Otherland
06-15-04, 11:03 AM
Hi, I just had to replace the batt in my bike pc and need help to reset the tire size. I have 26x1.75 tires on my mountain bike right now and there is not a pre set setting for that size on the bike pc. The manual says i need to do a roll out test. I understand how to do that but I was just wondering if maybe somebody has the measurment already or a link to a site that might have it. Im sure it would be more accurate than me trying to do it :-)

Thanks in advance ...... Jay....

Retro Grouch
06-15-04, 11:33 AM
If your goal is to be as accurate as possible, the roll out method is best. If you're willing to tolerate "close enough" just interpolate between the two closest adjacent tire sizes that are listed in your manual.
Otherland
06-15-04, 12:38 PM
I will try the rollout method. I was just hoping that somebody had already did it for that size tire. I was hopeing to find a website or page with the measurements already done. I dont know if my measurments would be very accurate or if it would be better to just choose the next closest size to my tire. I guess that would be 26x1.90

thanks Jay...

SchreiberBike
06-15-04, 01:57 PM
A roll out is the way to get an accurate measurement.

Approximations for typical sizes are available at Sheldon Brown's Site (http://www.sheldonbrown.com/cyclecomputer_calibration.html), but since tire size may not match the size on the label, it's just an approximation.
John E
06-15-04, 01:57 PM
Does this help any?

http://www.schwalbe.com/index.pl?modus=lang&punkt=262&abstract=1146&bereich=&einsatzbereich=&produktgruppe=

This website agrees with my own findings, that 26x1.95 tyres have about a 208cm circumference. This is the setting I use with my own cycling computer on my Schwinn.
p38karl
06-15-04, 11:10 PM
Cateye setting for 26x1.75 is 2023. Then, to fine tune setting, if computer reading is longer then actual distance you decreace the setting or is it is shorter than actual distance you increace setting.
sorebutt
06-16-04, 10:28 AM
here is what I do:


-I find a nice flat smooth sidewalk, or if you have a large enough garage.

- I put a small drop of grease (1/8") on the top of the tire tread, and ride the bike a few yards in a straight line. (sidewalk lines are a good guide)

- The I measure the distance between two stains of grease on the sidewalk.. :)

works like a charm..