Never mind- I just looked at the satellite image. Looks like a bunch of 22000 volt power lines overhead nearby- jct of Green Tea and Palmer. That can do it. A slight bit of corona on an insulator will spew all kinds of frequencies out, including the one that the wheel sensor sends to the computer. If you hear a buzzing from the lines, that's a pretty damning indicator of corona. Also, I see a transformer on the street view nearby. A (RF) leaky transformer can put out some pretty horrendous fields as well.

Different computers will have different sensitivity even if they're on the same channel. Also the bike structure acts as an antenna or director of waves, so a different bike will induce different local fields.