i have a trek incite 8i on my road bike. i was having trouble with it and
summed it up to a bad battery. i replaced the battery, reset the data and
made sure my magnet was property aligned. i took it out yesterday for the first time
and was having no problems during the 3 miles it takes me to get a paved trail near my house.

once at the trail head i stopped and put on my ipod and proceeded to ride.
the trail itself runs along side a large set of high tension wires.
the speed indicator then starts to get erratic posting either nothing or speeds
as high as 45mph, as low as 4mph and sometimes the actual speed i'm travelling.

i've debated replacing it but wonder if it is not either the ipod or the high tension wires that is causing it

Wireless computers do that.
Mine quits working when I turn my head lights on.
Plus reads 75 mph at one intersection.

Your device is probably certified under the FCC Part that requires it to not emit any harmful radio frequency interference and accept all RFI. So, if it isn't functioning correctly maybe the best thing is to report it to the seller and ask for a RFI fix. Probably won't do you any good because they most likely have decided protecting it against RFI isn't worth the cost.

This isn't just a wireless communication problem. Many device manufacturers go el cheapo when it comes to RFI unless some other regulation requires them to add the cost.

My Garmin Forerunner 305 and my Cateye Strada do not have interference problems with my MagicShine. My previous cycle computer did. I think it was an Avocet, but can't remember for sure. Garmins are the best!