No...but if you can afford it you might as well get something good. I rode a long time with my Trek bike computer which cost about 50 bucks. Then I wanted to do some more training so I started riding with a heart rate monitor. But then I wanted all out detail so I could meticulously track my improvements. It depends on what you need. If all you want is something to tell you how fast you are going then get something basic. You can even get a HRM included in a basic bike computer for under 100 bucks. But if you foresee yourself being a data junkie, do it right the first time.

Just my 2 cents.