martin_j001

Inside the transmitters (at least the ones compatible with the s520, 720i, etc) there was a little switch that allowed for different settings of "sending power/distance". In the instruction manual I got with my 520, it advised that if I wanted to use the speed sensor on the rear wheel I should consider changing the "sending power/distance" to account for this.

As other posters have said since my first post, the 3-4 seconds delay is absolutely normal with just about any wireless system--especially one that is trying to pick up two seperate signals (speed and cadence). If that is really that big of a deal, then its time to get rid of the Polar and go back to your wired computer and seperate HR setup.