Wireless computers and HRMs are particularly sensitive to washout... especialy if they don't use digitally coded descrimination. Things like headlamps, powerlines and traffic sensors can cause them to read erroneously or not at all. I have to use a wired version on my MTB because my shocks use a piezo-electric valve to govern the damping rates and the resulting EMI causes the computer to cut out. Also HID lights tend to produce more EMI than halogens. I don't have a problem with my halogen lights with my RB's wireless computer. I do occasionally have issues with traffic loop sensors.