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Old 05-10-07, 12:13 PM   #1
blochow2001
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Computer for my Sun CX tadpole

I bought and installed a Trek i9 computer and it does not work. I have been going back and forth with Trek customer service to resolve the problem and after about a dozen e-mails they don't know what is the matter and told me to return it.

To make a long story short the thing does not collect correct data. I can ride about 1000 feet and the odometer says I traveled 1 mile with an average speed of 18.2 mph. I don't think so.

So my questions is, what brands of computer do the riders out here use? I want to get a computer, but am leary of going through the hassle of buying from a catalog or on-line without knowing someone has had success with theirs. I have attahced a photo of the computer and sensor location on my ride, maybe someone can tell me if it is too close to the hub, Trek does not think so.

Thanks!
sensor1.jpg

sensor.jpg

stem.jpg
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Old 05-10-07, 12:55 PM   #2
banerjek
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This may be a dumb question, but did you calibrate it for your wheel size? Default settings would grossly overexaggerate speed and distance.
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Old 05-10-07, 01:35 PM   #3
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The first thing I'd check is what banerjek already suggested. A 20x1.5" wheel would have a circumference of a little over 1500mm, maybe as high as 1550 for a 1.75" tire. A preset default value is probably something like 2150mm, which would cause you to read about 40% too high. Having the pickup too close to the magnet can sometimes cause multiple pulses per revolution, so the next thing to do is increase the distance between the sensor & magnet. What happens if you mount the sensor/magnet to another wheel?
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Old 05-10-07, 02:06 PM   #4
blochow2001
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Quote:
Originally Posted by BlazingPedals
The first thing I'd check is what banerjek already suggested. A 20x1.5" wheel would have a circumference of a little over 1500mm, maybe as high as 1550 for a 1.75" tire. A preset default value is probably something like 2150mm, which would cause you to read about 40% too high. Having the pickup too close to the magnet can sometimes cause multiple pulses per revolution, so the next thing to do is increase the distance between the sensor & magnet. What happens if you mount the sensor/magnet to another wheel?
Yes, I rolled it out, 59.5 inches, or 1511mm. I went through that with the folks at Trek, sent pics of how I rolled it out, pic of the measurement, pic of the tire size on the 'puter, and alos did a double check and got the circumference with the radius and our friend pi. I did all of that and it is still way off. changed the battery, moved the magnet around a bit and it did nothing to imporve the accuracy. I'm bringing the unit back tomorrow, and hope to hear back from other riders with what they are using. Thanks for the input!
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Old 05-10-07, 03:07 PM   #5
banerjek
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Quote:
Originally Posted by blochow2001
Yes, I rolled it out, 59.5 inches, or 1511mm. I went through that with the folks at Trek, sent pics of how I rolled it out, pic of the measurement, pic of the tire size on the 'puter, and alos did a double check and got the circumference with the radius and our friend pi. I did all of that and it is still way off. changed the battery, moved the magnet around a bit and it did nothing to imporve the accuracy. I'm bringing the unit back tomorrow, and hope to hear back from other riders with what they are using. Thanks for the input!
I use a Cateye Astrale (actually I have 3 of them). I think they're great.

I just find this to be such a bizarre problem. I wonder if the sensor isn't defective. When you roll the wheel, are the speed readings "even" -- i.e. do they consistently accelerate and decelerate as you do or do they hop around?
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Old 05-11-07, 08:21 AM   #6
blochow2001
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Quote:
Originally Posted by banerjek
I use a Cateye Astrale (actually I have 3 of them). I think they're great.

I just find this to be such a bizarre problem. I wonder if the sensor isn't defective. When you roll the wheel, are the speed readings "even" -- i.e. do they consistently accelerate and decelerate as you do or do they hop around?
Actually, they are inconsistent as heck. I try to keep the same pace when I ride and I can go from 6mph to 21mph in an instant. I too think it is the sensor but Trek has no way for me to check it. I decided to get another one and give it a go this weekend. If it does not work out I will look into the Astrale you use, as at least I know it works for someone.

Thanks for your input, I appreciate it.
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Old 05-11-07, 09:23 PM   #7
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Tech tips involving magnet orientation and distance from hub here:
http://sheldonbrown.com/cyclecomputers/index.html

Only other suggestion I have is maybe Trek computers are not compatible with recumbents or trikes.
(Kidding)
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