How much faster can my commute be if I use a power meter?

Question

When biking to work, my routes have have stop signs, stop lights, and other interruptions every few blocks or so.

My understanding is that if I reach my power at target heart rate soon after stopping so that I still save glycogen, my commutes would be faster. I'm commuting five days a week. How effective is it really in practice? How much would I expect my average speed to increase?

Update with examples.

After stopping at stop signs, I plan to accelerate by keeping my power around 150W depending on my fitness.

After stopping at traffic lights, I plan to gradually raise my power to 150W because my heart rate would drop.

In both cases, my heart rate shouldn't exceed 180-age. With power, I know that I'm not overshooting it.

Update: Sample morning race to work ride in response to a comment.

Answer 1

With that many interruptions your own performance is unlikely to make much difference to your commute times. Sprinting for the lights, when safe, is much more likely to help. If it's mostly stop signs rather than lights, getting going fast might help but you don't need a power meter to tell you that. For me, leaving a few minutes later in the morning makes much more difference - not only are there more cars going my way and holding me up, but there are more coming the other way on narrow roads so passing the queues becomes harder. Bin day or a badly parked delivery van jump out of a list of timings.

You don't say anything about the distance and time but I assume you measure it. Have a look at the variability over recent rides, and try changing a few variables - can you even tell the difference between holding back until the fast bits, and going at everything hard?

A power meter is a training tool, and while you can incorporate commutes into a training plan that doesn't sound like what you're doing. Personally I prefer not to have a screen when commuting in case I look at it; I'd rather keep my eyes on the road. But maybe your commutes are in more benign conditions.

Answer 2

Commutes are generally regarded as "junk miles" for a reason. Even when applying training discipline to a commute, there's simply too much going on for it to be a meaningful effort. By focusing on performance during a commute, you're inevitably trading off awareness of your surroundings and putting yourself and others in danger.

If you are asking merely as a hypothetical, you could rephrase your question to be about how to optimize your interval training. For that, there's a wealth of knowledge out there, and you could easily sign up for a spinning class that will help you achieve those peaks you're looking for.

If you're asking in regards to a literal situation, please reconsider your point of view. As a mechanic who also helps coach new commuters, my advice is always to practice "slow riding." Switch to a fixed gear bike with a low gear ratio. The spinning practice is about the only good exercise you can do on a commute, and by going slow you're focusing on the right things: anticipating hazards, hitting lights when they're green, staying between car pileups at lights, planning your line, and enjoying the fresh air and scenery. With a low enough ratio you can still get a workout without being that insufferable Lance who shoals you at every light. Save it for race day, buddy, nobody's impressed.