I have a Magicshine headlight which I absolutely love paired with a Cateye Protege 9.0 wireless computer, (which I also love). My problem is that when the Magicshine is on, I get fluctuations in the speed display on my computer. As an example, the display will read a speed of 18.2 mph, then drop down to 14.2, even though there is not a corresponding drop in speed. Then it will bounce back up to 17 or 18 mph.

Does anyone know what the reason for this is, and have you ever experienced this issue with a wireless computer? If so, any possible solutions??

Thanks for any help you can offer

Hey, the interference is caused by the electronics in the light, try to move the light and the computer as far apart as possible.

I was having the same problem. I actually only had to move the wire for the MS and it works fine now. I have my computer and light on opposite sides of the stem.

My Avocet had the same problem. My Cateye Strada has had no interference problems. MY Garmin Edge 800 and Forerunner 305 are immune to these kind of problems.

Others who have had these problems have solved the interference with shielding on the connector.

I had the same problem. The only way I found to fix it was to buy a new wired (not wireless) computer.

The reason is that LED brightness is changed via pulse-width modulation, IE they turn the LED on and off a hundred times a second or so. Whenever you turn electronics on and off, it creates an electromagnetic pulse. If not well shielded and filtered, it can cause interference with wireless devices.

Running the wires along the opposite side of the stem seems like a good thing to try.

One of the many reasons why I don't like wireless stuff. I don't see much point in it anyway, they seems mainly to be good for chewing up batteries several times as fast.

I discovered that my new S-Mini flashlight jams my wireless computer/heart-rate monitor despite having no wires at all. I moved them about 1ft apart as a stop-gap measure, but decided this was A Sign indicating I should finally get a GPS and an ANT+ heart-rate transmitter, because I train on all my bikes after dark as the need arises. When life hands you lemons... sell the lemons on eBay and buy cookies.

My old NiteRider HID also was a jammer.

Thanks for the input everyone. Sounds like the LED pulse width modulation is the source of my woes. Anyone have any experience with DIY shielding for LED lighting? For what its worth, the computer and light are mounted on opposite sides of the stem and are as far apart as I can mount them. I may try putting the battery in a water bottle instead of mounting it directly underneath the stem and see if that makes any difference.

No experience but I can tell you that the most likely sources of emissions are the gaps between the metal connections (slot antenna) or the long wires between the battery and light head (basic wire antenna). While there is a science to shielding, unless you can simulate the RF environment or have the right equipment to measure the emissions it quickly becomes a 'black art'.

You probably can't do much to shield the computer head since it needs to pick up the signals from the transmitter on the wheel so your only option is to try to reduce the emissions from the light. Making the wire from the battery to the light head as short as possible and as far as possible from the computer might help. Changing the mounting orientation may help since an antenna's sensitivity is direction dependent. Putting the light wires on the opposite side of something metal from the computer head could help. Sorta ghetto but wrapping the light wire and/or battery pack in foil tape may help.

Good luck!

I had the same issue with my MS900 and my cateye strada. My solution was to mount the light on my helmet

One other thing that might help is to put a ferrite bead around the wire from the battery to the light head. You can buy them at any electronics part store or just scavenge one off the cable from a computer monitor, etc. It's the wide cylinder around the cable of your monitor and it's there to attenuate RF emissions from the cable.

i'm having the same issue; i was thinking of hacking together some aluminum foil around the wire or the battery. I'll see what works. Curious if anyone else has solved this one.

I went over the brink and got an Edge 500 GPS plus an ANT+ heart-rate strap, and it's immune to the combined effects of the S-Mini and a NiteRider Pro 1200. So folks might consider getting digital wireless next time they're buying a computer, if they plan to use it in combination with a light system a lot.

This is why I will probably never be talked into getting a wireless computer.

Yeah, I had the same problem, just moved them further apart.

I just stopped using bike computers altogether. On short rides I don't need it on longer rides I carry a GPS.