Is a Power Meter Necessary?
Yesterday a cyclist asked me if a having a power meter is necessary to race well. The flip answer is no, it isn't. Nor is a heart rate monitor, handlebar computer, fast wheels, light frame, or any other piece of advanced technology. The only things that are necessary are decent genetics and effective training.
I think the question he was really asking was, will a power make my training more effective? The answer here is, it depends. It depends first of all on how effective the athlete's current training is. If it's close to perfect then there won't be much, if any, improvement in performance due to a power meter. But if the athlete's training is less than optimal and the greatest room for improvement is intensity management, then a power meter has the potential to be quite effective.
But power meters are not magic. You won't race better merely because you have one on your bike. You've got to know how to use it. Reading Training and Racing with a Power Meter by Allen and Coggan is a good place to start. Having good analysis software, such as WKO+, will also make the data much more beneficial and open your eyes to how to train better.
Having coached and spoken with many athletes who started training with power meters I can tell you that the consensus is that they helped improve performance. A minority disagrees, however. Personal experience... I got my first one in 1995 and was amazed then at how it opened my eyes to what training on a bike was all about. I continue to learn about training more than 10 years later because of power meters. I believe most athletes will improve their performance by using one.