I am curious about your GPS cyclocomputers. That ones that do speed and heart rate cadence etc.

Now if i get a GPS type for my road bike? Does it still come with a sensor to monitor speed ? or does the sateliite track you on the bike?
Do you find GPS is more accurate for measuring speed then using a sensor types?

If i use a GPS system type, would the cadence sensor be only other thing i put on my bike?

Also are the GPS system interchangeable easily to a different bike? eg, use same device for road bike then move to mountain bike with out changing much settings

Also I like to mountain bike as well. I am riding closed in single track trails with lots of trees around, would i get the satellite signal to stop? otherwise what would be good system that doesnt conk out when in the bushes?

Thanks as i am in shopping for a new one. I like to get good information before making such an investment
thanks