"Most likely you ride a bike because you love riding. Or at least that is why you started. If having a computer on your handlebar adds to your pleasure, then by all means use one. …
On the other hand, if you start using your computer to tell you whether you have ridden "far enough" or "hard enough" or "correctly" today, or this week, or this year, then you may want to reconsider . We are all probably conpulsive enough in our work that we don’t need to be compulsive in our play as well."
Leonard Zinn – Zin & The Art of Road Bike Mainenance