I look at google to map out and plan rides. when I get back, I plug them into mapmyride to calculate distance. 1 of my 3 bikes has a computer and i havent ridden that bike in.... 3, 4 months? So I usually just make a mental note of what time I leave/get back to determine speed/pace. I dont know why I bother, I maintain a pretty consistent pace, it always comes out the same.