I used one of these computers for a couple of years and although it worked fine most of the time, the real problem was in summer heat, where the entire display screen would turn black so I couldn't read anything.  I first discovered this while on an 1,800 mile tour in Central America, where every day was near 100 degrees.  It was almost useless on that trip, except in the mornings before it got too hot out.  Later, I started experiencing the same problem others have reported of the contacts not making a connection.  At first that would only happen when it rained, but later it did it even when dry out.  I would avoid this one, unless maybe you just want to use it on a stationary bike indoors.