I knew a couple of folk who had trouble with the Bell computers. Why bother with a cheap brand wireless when you can get a good brand wired computer for under $20? A quick look at Amazon.com revealed 5 top brand computers for under $20. 1) Topeak Panoram V9 $17; 2) Vetta RT233 $17; 3) Vetta RT Classic $18; 4) Planet Bike Protege 5.0 $18; and 5) Sigma BC909 $20. Just look at each and get the one with the features and or price that appeals to you.
Wireless computers are great if their not the cheap ones. Reliability of a cheap wireless is about 1 to 2 years, plus the battery in the sending unit will last about 6 months, plus their a tad more hassle to install...but a wired job is also a hassle routing the wire. The best way to route the wire that I've found without having to resort to zip ties is to wrap the wire up the fork to the brake then around the brake cable to the bar, under the bar wrap to the computer. Make sure you leave enough slack so you can turn your handlebars from one extreme to the other so as not to pull the wire.
see this site for more details on installing a wired computer:
How to Install a Wired Bike Computer | eHow.com