Just remembered this and thought I'd post it before someone wants to get a GPS. GPS is good but it's not good if you get it close to the bike comp. I got mad phantom milage when the GPS was close to the wireless bike comp. (Shwinn wireless).
When you have the GPS far far away from the bike comp it will work ok and not cause phantom milage. I did not notice anything wonky with the GPS. It's just the bike comp that's going nuts. A good solution is to get a Minorura 'space bars' (the adjustable ones) and top mount it on the stem and mount the GPS there. The flash mode on some LED's and halogen modes will also cause phantom milage on the wireless comps.
Just wanted to give a heads up to people.