There has been a growing trend in performance cycling (racing, people
who are training for competitive events or just to improve fitness) to
use power meters to improve performance. The power is expressed in
watts and allows the rider to know exactly how much work they are
doing when riding. There are a few different techniques for measuring
power on a bike. Polar (same company that makes the heart rate
monitors) measures the vibration of the chain to measure power, SRM
uses a strain guage attached to the cranks, Power Tap (Cycleops) uses
a strain guage in the hub, and I believe there is a company that uses
a strain guage in the bottom bracket as well. My question: What is the
current market size in annual sales for power meters for bicycles,
what is the growth rate, and which companies are leading the market?
Thank in advance for your hard work on my question!

Hi, I can give you some advice on the major players, I work in the
industry, sales figures are going to be pretty hard to come by, as
most companies are private and do not publish such information.  It is
certainly a growth area though, dominated by a few major players.  Let
me know if you need more.