Originally Posted by
Eric F
Zero times have I lost GPS data due to clouds or trees, including riding in pretty significant conditions of both at the same time. How long are the tunnels you ride that GPS can’t extrapolate your route with reasonable accuracy?
You may not "lose" GPS during a ride, but its accuracy fluctuates greatly. If you've ever looked at a raw plot of GPS points from a ride, it looks like it was drawn by an alcoholic in withdrawal.
A speed sensor on the wheel can help alleviate the GPS drop outs. Your head unit may not know where you are for a while, but by using the speed sensor, it at least knows how far you have gone. A ride buddy of mine doesn't have a speed sensor, and when we're climbing in the redwoods, his GPS signal is bad, and his climbing rate (VAM) reading goes crazy.