Originally Posted by Wurm
That's
not the case with good wireless designs like the Cateye Micro that I and
kritter spoke of. I live in a fairly large metro area and ride in the city a lot. I've had exactly
zero interference problems with this unit since I started using it about a month ago. None at all from power lines, cars, train crossings, cells, etc.
And what's the BS about batteries? How often does one need replacing - about every year or two? It's not a big deal to take a quarter, open the back, insert battery.

If you're worried about it, replace the batteries once a year at the start of the riding season.
The sensor has a 70 cm. range to the main unit, which should be plenty for most needs. I have mine mounted on the stem with the sensor on the right side of the fork about 38 cm. away. The main unit detaches easily so you can take it with you.
The Micro works flawlessly every time I get on the bike, which is every day.
I suppose my point is this... For the teeny tiny wire run (that has to be run anyway, because of brake cables), wireless offers a lot of expense (and some potential hassle, which I'm glad you haven't experienced, but many people have), for almost no benefit. Like I said, a clean wired install is lightning fast, and will cause you zero problems ever. A clean wireless install might take 2 minutes less, but might cause other problems down the road.
Unless you have a special circumstance that would make a wire run highly impractical, you might as well save 20$ and remove the possibility of problems or additional hassle by going with a wired unit. I know that the wireless are high-zoot and all, but they really aren't that practical for most riders. Wireless computer mice, on the other hand.. Totally worth the hassle.
peace,
sam