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Need help mounting a Sigma Sport wireless system.(7 posts)

Need help mounting a Sigma Sport wireless system.ashleyrenfroe
Sep 21, 2001 4:52 AM
I have just taken this wireless system off of my mountain bike and am installing on my road bike. It does not look like it is gonna fit. The little magnet on the spoke is either too far away from the sensor, but when I move it closer it rubs the sensor itself. Does anyone have experience with this and how did you rectify the situation??
re: Need help mounting a Sigma Sport wireless system.nee Spoke Wrench
Sep 21, 2001 5:38 AM
It's been a year or so, but I think I remember a couple of tricks.

1. Don't mount the head on the handlebar till last. This is important.
2. Be sure to mount the sensor in front of the fork. That way, wheel rotation won't jam it into the spokes if the magnet touches.
3. Sigma sports seem to be real sensitive to the area on the sensor that the magnet passes. The sweet spot is marked. Try to orient the sensor so that the marked area faces the wheel magnet.
4. You can rotate the sensor from side to side to fine tune the distance from the magnet. You only have a couple millimeters of tolerence.
5. When you think that you have the sensor mounted adequately, hold the handlebar head close to the sensor and spin the wheel. If you get a MPH reading, that's good. If you don't, fool with the sensor mounting until you get it right.
6. Spin the wheel and hold the handlebar head in a few likely locations on your handlebar. If you still get a MPH reading, go ahead and mount it there. Sigma Sport wireless computers are sort of "line of sight" and will work in some locations on your handlebar much better than others.
Thank you!ashleyrenfroe
Sep 21, 2001 5:43 AM
Thanks spokewrench!! I believe what the trick is gonna be is to mount the magnet on a spoke that ties into the hub on the opposite side of the fork. Does that make sense? By sliding the magnet up close to the nipples (hehe), I should be able to keep close to the 5mm tolerance limit.

Thanks again!!
Thank you!Birddog
Sep 21, 2001 7:29 PM
My Sigma is very finicky. If I don't get the sensor and magnet just perfect, it won't read. When I say perfect, I mean perfect. It has to be much closer than the distance stated in their little impossible to figure out installation guide. When I switch wheels, I dread the fine tuning necessary to get a reading, and I have magnets on three different wheels so I don't have to switch. Since each wheel's spoke pattern is different, I have to adjust the pickup sensor for a reading. On one wheel, I have the magnet on a spoke that goes to the other side as you mention. You might also try some other mfg's magnet, the sensor shouldn't mind.
re: Need help mounting a Sigma Sport wireless system.CraigVM
Sep 24, 2001 12:43 AM
I can't say that I am an expert in bike computers, though I have mounted a dozen or so over the years for my own bikes. I would have to say I am an expert in the simple technology in which the magnet / sensor works as it is based off of a magnetic reed switch which is the same as used in securtiy system door & window contacts where I do have vast experience. I have recently found a trick that makes a world of difference....
The problem is the allowed gap between the sensor and magnet is so small due to the weak magnet that they use. Recently in the Security Alarm Industry, they have come out with "Rare Earth Magnets" which easily have the 10x the magnetic force of typical ferrite magnets such as come with every bike computer I have come across. I have some of these rare earth magnets which are perfect size to mount directly on the existing magnet "size of a small button being 3/8 round and 1/8" deep". Where before I could have no more than 1/4" distance between sensor and magnet. Now they work up to 1" gap. E-mail me and I will send you one for free.
re: Need help mounting a Sigma Sport wireless system.Birddog
Sep 24, 2001 6:30 AM
Where can an ordinary citizen purchase them. If you field all the requests, you'll be out of magnets. BTW, the Sigma doesn't use the round magnet, they have a long (about 3/4 inch) assembly that clips over the spoke and then locks with a slide mechanism. It is hard for me to remove them and change wheels, that's why I have a seperate magnet on each wheel (3). To utilize the round magnet, you'll have to get a Cateye or some other brand then glue the new magnet on, unless these other magnets come in some other shapes. Thanks for that good info though, I never gave much thought to how these worked, but I do understand reed switches.
The Sigma pickup sensor on the wireless model is a pain in the butt to get right also. Like most of these, it was designed to be universal, but you have to play around quite a bit to get it to work. With stronger magnets, that could potentially give you a lot of lee way in mounting it as well. I had the same problem with a Cateye wireless a few years back.
re: Magnets on SteroidsCraigVM
Sep 24, 2001 8:13 PM
I do have a handful of small square magnets. They are also the "rare earth" type and a bit smaller and would not be as strong but still a great deal better that the typical ceramic or ferrite type that I have found come with the bike computers. They, like the round button sized ones, come with little cutouts of double stick tape though I have found their magnetisim along keeps them in place. One would need to make sure they mount them as they naturaly want to sit as if you force the like polarities of two magnets together, they will weaken each other. If given your address I would be happy to send one of each style to you and just ask that you tell me if they work out for you.
CraigVanMeter@juno.com