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

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.

• I'm confused. If you want to reach a target heart rate, don't you need a heart-rate monitor, rather than a power meter? Feb 24, 2018 at 19:11
• Can you clarify your question? As an aside, I have used a power meter to estimate the time saved at the same average power for two parallel routes, one on a "bicycle boulevard" with many stop signs vs. the other on an arterial with very few stops. Alternatively, I could have used the power meter to determine the extra energy used for two tips of the same elapsed time. Feb 24, 2018 at 20:20
• TBH if you're talking about peaking at 150W, just get on with pedaling. Your fitness will improve until pretty soon you can reckon on that being your average power for the ride. If you believe Strava (don't, I'm sure it overestimates) that's the sort of power I average over 3 hours, and I'm nothing special. In fact that agrees with figure 2.4 (the curve for "healthy men") in Bicycling Science. You've just prompted me to put a fresh battery in my heart monitor for tomorro's ride Feb 24, 2018 at 22:36
• If you are using the 180-age formula, it's probably a good idea to find your actual heart rate thresholds.
– ojs
Feb 24, 2018 at 22:38
• You'll be slower, because you spend too much time studying the meter instead of biking. Feb 25, 2018 at 13:05

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.

• @Criggie I believe you're right, but avoid it myself because of an old knee injury -- so I change down for stops and spin away instead. Feb 24, 2018 at 20:27
• This article suggests that 1/day would be fine, the 2nd at lower intensity. But these are quite short rides, and to be honest 10km in 40 minutes isn't that intense overall (I'm doing 8km in ~25 minutes even on my hybrid, and the limit is the traffic). If your peak output is high over that timescale, you must get a fair bit of recovery time. This is interesting for single short sprints; I haven't found anything for repetition. I reckon you're over-thinking it Feb 24, 2018 at 22:23
• Honestly, I wouldn't worry about your body running out of anything if you're cycling at 15km/h. You're definitely over-thinking this. Feb 24, 2018 at 23:50
• @Han-Lin No, really. Unless you're cycling up a continuous hill, 15km/h is a leisurely pace, even as an average speed. Even if you're spending a quarter of your time stationary at stop lights/signs, which would be a huge amount, you're still only averaging 20km/h when you're moving, and you're getting ten minutes of rest in a 40-minute ride. If 15km/h is your average speed, it doesn't matter what bike you're on. To go faster than that, you don't need expensive gadgets or a training plan or anything like that -- you just need to improve your general level of fitness. Feb 25, 2018 at 13:13
• @Han-Lin At your level and mine, the way to improve is to push yourself a little bit on each ride. Don't go crazy, because you don't want to arrive at work in a sweaty mess, but spend some time getting out of breath each ride. I've never used one but every training plan I've seen contains both high-intensity intervals and longer periods towards the upper end of your sustainable effort. Your "smart" plan seems to eliminate any kind of intensity: you're basically proposing to get fast by practising being slow. Ultimately, though, if buying a power meter makes you happy, go for it. Feb 26, 2018 at 10:16

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.

• There are plenty of other things you can practice on some commutes -- for example I tend to sit and spin up hills, so consciously getting out of the saddle is good practice (I don't race, being more into distance). You can also practice various hazard-handling techniques if you get a clear/safe bit of road -- bunny-hop or at least pop the front wheel over any cracks in the road surface that are big enough to feel (not recommended in traffic). Feb 26, 2018 at 10:24
• yeah for sure, i was admittedly trying to understate the value of skills training during a commute. i think being able to plan a clean and safe line through a gnarly traffic situation is an extremely valuable skill for racing, especially crits. i enjoy practicing my balance by track-standing at lights (i know i look like a show-off but it entertains me). basically the one thing you cannot do is exactly what the OP is looking for - testing peak performance metrics. but yeah, commutes can be fun to test some soft skills like cadence, etc. Feb 26, 2018 at 15:29
• If I could track stand I'd do the same! I've got 1 straight I could measure on, evenings only, but the preceding hill is at the pace of the traffic and would dominate my performance -- so the plan is ride safe, ride fast, in that order. +1 BTW. Feb 26, 2018 at 15:32