remember, you're relying on satelites, not towers with repeaters.
/quote]
Sorry but I disagree with you on that one. XM has towers/repeaters in many cities. I;m not sure if Sirius has any or not. XM 's sats are in orbit near the equator, so if you live in the northern US, your signal on a motorcycle may be dropped at times due to your body blocking the signal since the angle from your antenna to the sats is very low on the horizion. Sirius has their sats in a figure "8" orbit over the USA so in most locations you get a good signal on a motorcycle. XM added local repeaters to boost their signal in some cities for this reason. So where you are located does has some effect on how well the radio signal is going to work. This all has very little impact on a car installation as the car body acts as part of the antenna (lots of metal) where a motorcycle has very little metal. Your mileage may vary.