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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.

enter image description here

Brian
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    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? – David Richerby Feb 24 '18 at 19:11
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    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. – R. Chung Feb 24 '18 at 20:20
  • @DavidRicherby I meant power at target heart rate. Correction made. I'm sorry for my mistake. – Brian Feb 24 '18 at 21:37
  • @R.Chung More details have been added. – Brian Feb 24 '18 at 21:55
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    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 – Chris H Feb 24 '18 at 22:36
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    If you are using the 180-age formula, it's probably a good idea to find your actual heart rate thresholds. – ojs Feb 24 '18 at 22:38
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    You'll be slower, because you spend too much time studying the meter instead of biking. – Daniel R Hicks Feb 25 '18 at 13:05
  • Where are the graphs from? – ojs Mar 06 '18 at 08:51
  • @ojs it looks like the analysis page on Strava (example is one of my recent rides -- the one I mention a couple of times in other comments) – Chris H Mar 06 '18 at 09:08
  • @ChrisH I meant the source of the data, in my experience speed and HR graphs are usually not that smooth. – ojs Mar 06 '18 at 09:25
  • @ojs, that makes sense, though if I zoom my ride in to the same length (16:40) the speed doesn't look that much more noisy, and I don't have HR data to graph. The long straight lines on the estimated power suggest sparse data, only partially match with similar lines in speed (which you might expect to be flat), but match better with HR. So bad GPS data? Urban canyons? But the HR shouldn't depend on GPS (unless the app logging it is rubbish, which it might be) – Chris H Mar 06 '18 at 09:35
  • @ojs The smoothness looks fine to me, for a ride of that length. The second half of it has a lot of holes in it, though, where Strava just interpolates a straight line. – David Richerby Mar 06 '18 at 11:30
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    @ChrisH The Strava app tries to record a GPS position about once a second and annotates each position with whatever sensor data it has (heart rate, power, cadence, etc.). Unfortunately, that means that you lose everything if you lose the GPS, because it only records sensor data as part of the location track. The second half of the ride has a lot of GPS holes in it but up to about 7min looks fine. – David Richerby Mar 06 '18 at 11:32
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    What, really? Making up data when GPS fails is bad enough, but discarding other data measurements and then making them up when GPS fails is just ridiculous. The first 7 minutes or so look kind of realistic but filtered to me. – ojs Mar 06 '18 at 11:49
  • @DavidRicherby then I guess the app is rubbish for recording with poor GPS. The one I use is much better; if I had such poor GPS signals I'd add wheel sensors and it would use those. – Chris H Mar 06 '18 at 11:59
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    @ojs I suspect the website is plotting a straight line between the points it has. That's the default in Excel graphs as well (and I criticise that too, or at least my students' unquestioning use of it). Of course a gap would be better. There may also be some filtering. I set low but non-zero GPS filtering in IPBike because with filtering off I appear to zigzag across the road and my distances are inflated. This probably smooths the speed a little as well – Chris H Mar 06 '18 at 12:04

2 Answers2

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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.

Chris H
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  • A max effort standing start, in a big gear can be an excellent training technique. – Criggie Feb 24 '18 at 20:19
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    @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. – Chris H Feb 24 '18 at 20:27
  • Won't it use up your glycogen if you do it 10 rides a week? At high intensity, you burn mostly carbs. Let's assume 10k and 40 minutes using bike boulevards. – Brian Feb 24 '18 at 21:46
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    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 – Chris H Feb 24 '18 at 22:23
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    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. – David Richerby Feb 24 '18 at 23:50
  • @DavidRicherby You're right that on a flat with no interruptions, that's more than an all day pace but 15km/h was the average speed after taking into account hills, stop signs, and red lights which varies the resistance quite a bit. I ramp up my heart rate slowly when accelerating from stops because I don't want to overshoot my power which happened a lot without my HRM. I feel that not having to ramp it up too slowly would save time. If it does save 2 kph, that's almost like upgrading from a hybrid to a road bike. – Brian Feb 25 '18 at 07:06
  • On rides of that length, traffic lights are where you get your breath back (and downhills if you can't pedal hard for safety). If heart rate training is your thing, do that. Overshooting your heart rate is more likely than overshooting your power though. – Chris H Feb 25 '18 at 07:50
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    @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. – David Richerby Feb 25 '18 at 13:13
  • I do hit 25 kph. My strava data tends to show around 18 kph. 2 years ago I've gone all out biking to work which was why even at that speed i found it strenuous and plateaued. I feel the need to avoid high intensity zones. – Brian Feb 25 '18 at 16:39
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    At your level, and mine, glycogen depletion on training/commuting rides isn't a big issue unless you're planning on a big important ride within about a day. My big rides undoubtedly wipe out my glycogen reserves, and the rest of my reserves if you've seen the state of me afterwards. I can still commute the next morning; yes I'm slower but only like turning a normal traffic day into a moderately bad traffic day – Chris H Feb 25 '18 at 16:48
  • @DavidRicherby It should allow smarter training assuming that it really works. Power meters are cheaper than e-bikes and not driving saves up money for a power meter in quite a short time. – Brian Feb 26 '18 at 01:18
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    To further reinforce my point: yesterday afternoon I did 76km and about 800m of climbing. I didn't touch my snacks/gels and only drank water. By your argument I should still have been really quite depleted this morning. This morning's commute was quicker than average despite a bit of extra traffic. – Chris H Feb 26 '18 at 07:38
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    @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. – David Richerby Feb 26 '18 at 10:16
  • BTW I also ran my heart monitor. It kept losing contact (it's old), but I was cruising at around 140-150 on the flat; at the top of a climb it reached 170 but dropped quickly enough that I'm happy. Strava gives me an average of 133W and it doesn't know about the headwinds I had much of the time. I won't make a habit of riding with the heart monitor though, and if I was buying sensors I'd be buying a cadence sensor. – Chris H Feb 26 '18 at 15:35
  • @ChrisH I've uploaded a sample race to work ride from Strava from Nov 2016. I raced to work almost every work day. My sprints upstairs after the ride may not have been explosive, probably indicating exhaustion. My MHR is around 190. Also, a hybrid bike was used and it wasn't fitted. – Brian Mar 06 '18 at 02:56
  • @Han-Lin That's very different from the 10km in 40 minutes you originally claimed. – David Richerby Mar 06 '18 at 02:59
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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.

Nathaniel Hoyt
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    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). – Chris H Feb 26 '18 at 10:24
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    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. – Nathaniel Hoyt Feb 26 '18 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. – Chris H Feb 26 '18 at 15:32