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Question on CatEye Computer

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Question on CatEye Computer

Old 08-31-05, 11:14 AM
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djlen3
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Question on CatEye Computer

Hello Folks,
I'm new here but not new to cycling and I have a question.
I just installed a Cateye 'Micro Wireless' computer on my road bike and left my old(12years old) Cateye on to compare readings between the two. All measurements were surprisingly similar, but the 'trip distance' on the new computer was almost 1/4 mile shorter than the old one on a ride of 14 miles.
This may sound like not too much initially, but I've ridden well over 1000 miles this summer and those 1/4 mile differences add up.
First question: The old computer's magnet for measuring distance is closer to the hub(center) of the wheel than the new one's. Does this make a difference in mileage recording? If so, how can I compensate for this. There are setting changes I can make for wheel size, but I don't know whether that's the way I should go or not.
Second question: I have wheel size of 26 X 1 1/8. If anyone out there is familiar with the make and model of Cateye that I have can let me know how I can change settings to compensate for the differences in mileage, I'd appreciate the input.

Orrrrrrr......if there is a place on this forum that I would be more apt to get answers, I'd appreciate someone steering me there.

Len
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Old 08-31-05, 12:38 PM
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Shouldn't matter where you magnet is in relation to the inner/outer wheel. This is what I did and you may want to try. Pump your tires up to your normal riding pressure. Put the stem (on the tire with the magnet) pointed towards the ground and then roll the bike forward with you on it till the stem is down again. Then measure that distance and input that into the computer.

I did this on our tandem. Ended up being 3/4 inch difference between the distance with us on it vs. us not on it. Before that our computers (captain and stoker) were off a tad, now they're both in synch. How accurate they are we don't know yet. I plan to see how they fare over a long distance course compared to our two cars.
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Old 08-31-05, 01:18 PM
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Sounds reasonable, but I think that there is a way to program these new computers so that they can compensate for differences in wheel/tire sizes and also magnet placement on the spoke.

Len
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Old 08-31-05, 01:41 PM
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Originally Posted by djlen3
Sounds reasonable, but I think that there is a way to program these new computers so that they can compensate for differences in wheel/tire sizes and also magnet placement on the spoke.

Len
Right that is what he is saying. The magnet placement doesn't matter but that roll out number is what you are interested in. When you are doing your setup there is a 4 digit number which relates the the circumference of the wheel/tire combo. The most acurate way to get this number is to do as Doggus said, measure the roll out of your wheel with you on the bike and the tire inflated to your riding pressure.

With a 26" x 1.125" tire your number should be less than 1995 (theoretical for a 26" x 1.4" wheel/tire). That number is the roll out in mm

Edit: Ok here is the PDF of your user manual that tells you how to set the wheel/tire size. http://www.cateye.com/en/pdfs/MC100Wv2ENG.pdf Look on page 2. It also gives the theoretical circumference from your wheel as 1970 mm so when you do a roll out you should get near that number. If that isn't the number that is in the computer right now your speed and distance are off by whatever the percentage difference is between the numbers.
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Last edited by Grasschopper; 08-31-05 at 01:50 PM.
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Old 08-31-05, 02:38 PM
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Thank you Grasschopper ( and Doggus). That is exactly the explanation I was looking for. I had already downloaded that manual but was not sure if that number stood for 'roll-out'.
Now I will know how to adjust/compensate.

Thanks again

Len
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