I have been preaching the importance of training with a power meter for years. There are countless reasons for a cyclist training to be faster to utilize power data, but a few recent instances with athletes inspired me to get something together to post.
The analogy that I use is that from a training perspective riding without a power meter is akin to going into the weight room when all the weights are different sizes and not marked and you just start lifting things randomly until you are tired. Could you get stronger? Of course, but can you plan and chart a course of training and monitor that gains are on track? No.
Cycling luckily has the element that it is really flipping fun. Not every ride (or even the majority of rides) is about going out to hit specific intensities to drive our aerobic engine to grow. We ride singletrack to descend awesome trails and we cruise to the coffee shop. As well some cyclists just need to get consistent with riding and build a general endurance base. These things do not require a power meter to be successful. But when a cyclist is riding consistently and wants to rise off a plateau, then a power meter is the best device for leaving no doubt that we are performing the work we need to do to improve.
One of the professional cyclists I coach, Brad Auen, just won a power meter at the very awesome Dakota 5-0 race. This was a huge asset to our training as Brad had been doing everything based of Heart Rate. He and I often spoke on how to best use the HR info and we did a good job making progress with what we had. But both of our eyes were opened a lot within just weeks of working out with Power. First of all I found out he was quite a bit stronger than I realized! Certainly good info to have! That changed our approach significantly in the training schedule. Building fitness to compete is far different than tweaking training to be ready to win a specific race. Brad and I can focus on getting him to the finish line first (something he often does already)! Power data changed our mindset dramatically. As well it really drove home for Brad the differences and short comings I had been telling him about when training off HR. Now instead of his effort tapering off towards the end of interval sessions as the cardiac drift keeps him in the training zone while the effort fades off, he now is digging deep to finish interval sessions in his power ranges and getting a lot more benefit from the crucial last interval and last minutes of efforts.
In a completely different scenario my athlete Heidi Dohse is using power for us to learn how her pacemaker works under the unique stresses of bike racing and what kind of training she really needs to continue to grow. With all athletes there is a ton of good that we can get from comparing the graph lines of Heart Rate and Power, but with Heidi this becomes even more critical. One odd thing we see repeated is that it takes roughly a minute for her pace maker to respond to a sharp hard effort. If I were to put in a hard 12 second dig, you would see a bump in HR from that right away but it really would not be that significant. With Heidi - she will push ~400 watts for 10-15 seconds and then regardless of the terrain and effort ahead (it could be coasting downhill) we will see the pacemaker respond with a big spike that is typically her highest HR values of the ride nearly a minute after the effort. Conversely Heidi experiences none of the cardiac drift that Brad does. In stages of the Breck Epic her high and low values could be as close as 15 beats apart. We are able to pull info from Heidi's rides and give her pacemaker manufacture, Boston Scientific, feedback on their product that really could not be seen any other way. Luckily for us all Boston Scientific is committed to the success of Heidi's racing and willing to fold this information into development.
In both cases we gain objective data that is allowing us to make the adjustments in training that make having a coach a very valuable asset. Without power I feel you are always training on theory and with it we make it a personal program that is responding to how you uniquely adapt to training stresses.
I hear often that people are worried about the power meter taking the fun out of riding. Trust me! There is no one who is more in it for the fun than I am. I have always found that the power data only increases the fun factor. Yes there are times that I take off the head unit and only look at it after the ride. I do find it incredibly interesting (fun) to ride off perceived exertion and then compare the true data to the effort I thought it was. There are many times I am much more interested in what a riders effort level is when they think that they are putting in an 7 out of 10 effort, instead of forcing the effort into a little box of a training zone. Powering a bike down the road and trail is cool, really understanding the effort required to do that makes it all the more radical.
I have been helping people through purchasing the right power meter for themselves for years in all kinds of different capacities. I have strong opinions and will gladly share them with you if you have any interest. Call or email me anytime and I will be thrilled to talk it through with you.