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Old 02-13-13, 07:40 AM   #1
TampaRaleigh
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New computer with vintage sensors?

If I splice a new (Cateye Strava) computer harness to vintage sensors, do you think it would work?

Cateye gave me the canned legal mumbo-jumbo resonse:

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Cateye does not recommend splicing, soldering or otherwise separating and rejoining the wires of CatEye bracket/sensor kits.
I have experience in electronics repair and soldering, so that's not the issue. I'm just wondering how sensitive the head unit might be to different "pulses" that it gets from the sensors.

(YES, I have a good reason for wanting to do this.)
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Old 02-13-13, 09:37 AM   #2
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The wired sensor is a reed-switch that breaks a circut when the magnet passes it. There isn't any magic going on.
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Old 02-13-13, 09:47 AM   #3
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The wired sensor is a reed-switch that breaks a circut when the magnet passes it. There isn't any magic going on.
Well... that makes it even MORE likely that my plan will work. I was thinking that there was a coil in the sensor that generated an electrical pulse when the magnet passed. I've never disassembled a sensor before.
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Old 02-13-13, 09:50 AM   #4
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This is my reason for wanting to undertake this splicing job:

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Old 02-13-13, 10:29 AM   #5
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This is my reason...
I say splice away.
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Old 02-13-13, 10:52 AM   #6
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Agree. I know of no system that uses anything other than reed switches for cadence and wheel sensing. Thought there are other possibilities, I don't think they are as practical for this application.
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Old 02-13-13, 06:44 PM   #7
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The wired sensor is a reed-switch that breaks a circut when the magnet passes it. There isn't any magic going on.
I always thought they were really thin wire coils with the magnet generating a tiny current in the coil. The reed switch makes much more sense.
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Old 02-13-13, 06:55 PM   #8
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Agree. I know of no system that uses anything other than reed switches for cadence and wheel sensing. Thought there are other possibilities, I don't think they are as practical for this application.
The older Avocet cyclometers (like the '50') used a Hall effect sensor with a small ring mounted around the hub instead of the usual single magnet attached to a spoke. Those Avocets did have the advantage of responding more quickly to speed changes, but their sensor was probably less cost-effective than the reed switch used by everyone else.
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Old 02-13-13, 08:50 PM   #9
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I had always just assumed they used hall effect sensors. Seems like you could actually count spokes, like they do with gear teeth

I think that attaching to the stub of a wire at the headtube end is going to be a problem
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Old 02-14-13, 09:53 AM   #10
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I think quiescent power draw is the key characteristic. Reed switches may have a limited life and slow response, but at the total usage and rate on a bicycle, they are the best current solution, IMO.
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Old 02-14-13, 10:21 AM   #11
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I had always just assumed they used hall effect sensors. Seems like you could actually count spokes, like they do with gear teeth

I think that attaching to the stub of a wire at the headtube end is going to be a problem
I'm going to snip the sensors off of the new harness, and draw the new wiring down the downtube. I'll pull the old and new wires out through the bottom bracket shell to solder them together (that'll give me plenty of length in case of error) and then I'll tuck it back up into the downtube and reinstall the bottom bracket.
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Old 02-14-13, 06:45 PM   #12
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Good luck with the wires. They are extremely thin and difficult to handle. I've tried re-wiring headphones and it is almost impossible to make it work, and I think these are even thinner. I gave up on the headphones and just bought another pair. With the cheaper wired computers I'd just bite the bullet and put in a new set. I've built a fair amount of electronic equipment too, although far from an expert, so I wasn't a noobie at soldering and handling the stuff.
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Old 02-15-13, 11:38 PM   #13
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Interesting. Is that a modified frame or full custom?

I'm guessing it will work but like zacster mentioned, the solder job will be tedious. I know I couldn't do it but some can. When I was a kid, I remember my dad doing several custom harnesses for obscure reasons. One was putting a Campagnolo ergo brain on a bike Friday tandem. He had to extend the harness and add a disconnect,
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Old 03-06-13, 07:31 AM   #14
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Interesting. Is that a modified frame or full custom?

I'm guessing it will work but like zacster mentioned, the solder job will be tedious. I know I couldn't do it but some can. When I was a kid, I remember my dad doing several custom harnesses for obscure reasons. One was putting a Campagnolo ergo brain on a bike Friday tandem. He had to extend the harness and add a disconnect,
It's a modified 1985 Bridgestone 700. The wire routing was added sometime before 1988. (It had a California registration decal from 1988, on top of the repaint.)

I took on the surgery last night... and it was a success! I pulled the old wires out through the bottom bracket shell, fished the new wires down the downtube, spliced and soldered, covered it all up with a couple layers of heat shrink, and put the bottom bracket back in.
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Old 03-06-13, 08:37 AM   #15
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Go wireless ...
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