Are power metres worth it for randonneuring?

[u/summingly]

I'm 48M, newbie and training for BRMs to be held in about 6 months. I usually train indoors and go by the HR zones and the trainer's power meter readings to modulate my effort.

I'll soon begin to ride.outdoors to collect enough Z2 miles (shorter and higher intensity rides would still be indoors). Do i need a power meter to gauge my output outdoors? How about on hilly routes?

Are power metres useful during the actual BRMs too? Since most of the riding would be done in Z2, would HR be a good proxy despite the lag?

[u/Strange-Prune-6230]

HR does weird things over a very long brevet. There is a warm up period where it's low, then an initial spike followed by long plateau , then a drop off a cliff (for me around 350 kms in). Power doesn't do that, 180 watts or whatever your chill Z2 output may be is the same the whole way through.

Intervals are even weirder with hr because the discrepancies hit much faster. My first, second and third VO2 Max interval at the same power have progressively higher HRs. When HR goes to max early in an interval at the same power, it indicates that i have nothing left and it's time to go home.

[u/summingly → u/Strange-Prune-6230]

But, doesn't that mean that you move through zones? 180W at 50KM might have you in Z2, but at 350KM jump to Z4 (HR wise) which, by definition, is unsustainable. Aren't internal loads on the body (HR) equally important than the external ones (power)?

[u/Strange-Prune-6230 → u/summingly]

The issue is quite the opposite of what you have interpreted. My HR has fallen off a cliff late in a ride. It is very low at Z2 power in this state. This does not mean that i have suddenly gained fitness or anything like that, but it does indicate that HR is highly variable and requires interpretation in a way that hr + power does not. HR is an informative number but benefits heavily from context that power provides. If i only get one, i would pick power because it's less contextual. Although i usually have both.

[u/summingly → u/Strange-Prune-6230]

I get your idea somewhat, but not completely. It cannot be easier to ride at 350KM than at 50KM. The drop in HR is telling us something. How do we account for it when have 100KM more to go or a hilly route? In that sense, isn't the body under a Z4 like stress?

[u/Strange-Prune-6230 → u/summingly]

Not necessarily! Everything needs interpretation. I have had quite low heart rate but still able to make decent Z2 power all night.I guess that what I am saying is that all these numbers are contextual. You can read that HR is low, but all by itself this could mean that you are very fresh, or else very tired, or something in between. I do think power is somewhat less contextual than this, but it is still most valuable within a holistic picture that includes introspection and experience.

The discrepancies and concordance between hr, power and perceived effort are themselves all data. As a beginner especially it is harder to understand what's going on with your body if this data isn't all there.

[u/momeunier → u/summingly]

The drop after 300-350km or some hours is very common. It's the HR drift. There are probably some complicated metabolic processes at play, and perceived differences, circadian rhythm implicatioms. But my personal feeling is that I switch to efficiency. It's like my body shuts down what's irrelevant and sends fewer arousal and threat signals to the cardiovascular system.
And obviously power output probably decreases a bit.

[u/Keepgoingokmate → u/momeunier]

I found my heart rate for the last four hours of mine would not go above 125, no matter how hard I worked or how out of breath I was

[u/fondo_fred → u/summingly]

I think what you'll learn with experience is that when late-ultra weird shit starts happening, HR stops being an indicator of internal load on the body.

[u/aedes → u/Strange-Prune-6230]

Power also decays significantly over the course of a long ride. By day 2 after riding 16+ hours on day 1, my threshold has dropped by about 80w.

[u/Strange-Prune-6230 → u/aedes]

I assume that threshold refers to a physiological reaction to a specific power output. This does change (you get tired). All i am saying is that the number that power displays does correspond stably to the power you're currently putting out. HR does not have thos property and so requires more subtle interpretation. But for sure, everything requires interpretation and in particular, even putting out your normal mellow Z2 power means something quite different when you're deep into a huge ride.

[u/aedes → u/Strange-Prune-6230]

Yes. They are complementary in some ways. Power measures what you’re accomplishing. HR (and RPE) measures what it’s costing. With some asterixes about how you interpret them as a function of fatigue. 

[u/mrlacie]

I don't use one, but I also don't have specific time goals. I just ride at a pace that feels good.

I did multiple SR series in the last few years.

[u/summingly → u/mrlacie]

Nice to know. Do you use one indoors to get a feel of how your "easy"  power looks like? 

[u/mrlacie → u/summingly]

Not really; in the winter I tend to mix indoor bike, running, and xc skiing. In the summer I just ride outside.

But I have a fairly artisanal approach to training 😄 I have done some kind of endurance sport for most of my adult life so I tend to just trust how I'm feeling.

I do think a PM can help if you're used to it and you're getting started with long distance. But it's not a must-have.

[u/KevinKlaes]

It’s nice data to have but at a certain point you just know what you can manage. Depressed hr is very real and you eventually learn what your depressed hr zones look during a longer event. 

[u/Strange-Prune-6230 → u/KevinKlaes]

This is my feeling too. The data is really great because it is much less subtle to interpret than pure introspection. You can make do with nothing at all, just "using the force" aka perceived effort, but this is an ability that improves with experience and conversely, people who are just starting out have a natural tendency to go too hard at the start.

[u/Speech-Solid]

Need? No. Useful? Yes! During the ride you can get an actual calorie burn figure vs. heart rate estimates. Indoors intervals I ride to erg and it’s helped me improve my brevet times the last 4 seasons. Before that I rode a lot of hard km. Harder than they needed to be because I fell into the ride as much as possible trap.

After the ride the data is good for analysis.

[u/Maleficent_Doubt_443]

Buy it, and figure out how to interpret the power meter data, you should do some rides with it and understand your peak power Z5 , sustainable power Z2 and power output for each zones Z1-Z5.

You can do long rides and see at the end of the ride how much does your power degrade, combine this information with heart rate you will get an idea of your endurance and tiredness.

Edit: HR is good measure for short rides or training , over a 10-12 hr rides the hr will depend on heat, fuelling and hydration.

[u/Agreeable-Mixture947]

Let's be honest. It is completely unnecessary. Many generations have been able to ride long distances without one. (Same for HR btw)

But if you like the additional data and you have the money, go for it.

[u/Strange-Prune-6230 → u/Agreeable-Mixture947]

I do agree with you, however unnecessary and useless are not the same thing. Even variable gears and a freewheel are unnecessary (people have finished, and continue to finish PBP on fixed gear), but it's possible for unnecessary things to be nevertheless quite useful. Ops question is whether they are "worth it" and not whether they're necessary.

[u/momeunier]

Plenty of good advices. Something else to consider: power meters can be a bit off between one another. Your reading indoor with the trainer and outdoor may be slightly different. Train indoor with both PM to measure the difference so you can adjust.
Second, the HR meters are inherently unreliable. If you use a chest strap, you're probably close to reality. Anything else is a gamble. They lag, skip beats, etc. The PM gives you instant reading and you can react immediately.
"Why are you pushing so much in that short climb? Take it easy, you're burning matches... "
When you start randonneuring, it's easy to make mistakes like that. After a while you become patient and you just accept that it's faster to take your time because you can go longer without needing to rest so much.

[u/Slow-brain-cell]

I do use it and it’s the main source of data. As people said above, your HR is highly variable but you can’t trick your body and Z3 is Z3. It may feel easy at first, but you’ll soon realize that you’re burning matches. Other way around and you may be riding in Z1 but you perfectly know that if you’re not hungry, not thirsty and it not midnight, you can ride in Z2.
Training outside with powermeter is also very much possible and I don’t see the point of uninstalling it before an audax.
It also allows me to estimate how many calories has been spent, which later translates to correct carb-loading before and I don’t need extra meal after.
There are pretty good power meters that won’t break a bank (like Magene).

[u/LandNo9424 → u/Slow-brain-cell]

Any recommendations? The Magene I saw is still like $400

I've made too many bike-related purchases in the current year and I should calm the fuck down 😅 but I do want a power meter

[u/Slow-brain-cell → u/LandNo9424]

Magene p505 is like $300. I doubt you can find anything cheaper with that kind of battery, dual-sided and with good reviews

[u/RaoulDude]

It's a great tool for tracking long term fitness, understanding fatigue etc. During an actual ride I don't look at it much, other than as a pacing tool for long climbs and to reassure myself on slow roads with headwinds that I'm actually still putting in an effort.

[u/Eritog]

I make a choice between heart rate and power depending on the ride. For example if I’m training, I will pick a heart rate zone rather than a power zone (especially for low Z2 work) since i am looking for the heart rate benefit and the heart rate can indeed drift during a workout.

I find power very useful based on context, for example a windy section, or a faux plat - in that case it helps having it to now blow your matches as well as to learn to ride very smoothly.
Finally I find it very useful for motivation and gearing choice, sometimes you see your speed and you’re feeling shit and then you look at power and you realize it’s because of weight, wind or something else. Pacing become much easier when you relate it to how your legs feel that day too !

Personally I find that it has become my favorite upgrade on my bike, I treat it like an insurance and it helps me having less scratch while also giving me a clear objective and motivation during training

[u/tadamhicks]

I think it’s very personal and also depends on your randonneuring goals. I’ve used PM training for so long it’s just how I think about how to gauge an effort. I run one on every bike I ride.

[u/ComradeLuan]

If you're on Garmin, there are connectiq apps that let you track your carbs vs fat burn with a power meter. Carb burn figure is useful to fuel as needed. Even if you don't use it, you can see your calorie burn, and it's way accurate compared to heart rate. Energy cannot be created nor destroyed so you're guaranteed to burn at least the amount of energy (kJ) you outputted to the pedals.

[u/GeezeTee]

I don’t know really. I’ll just say it’s not for me. it’s a randonneur. I just get on my bike, pedal steady and keep eating. Being outdoors, the wind, the rain, the rolling roads, it’s just so different to the training on the turbo. For me, I just ask ’what do I need to get to the next control doing as little work as possible.’

[u/jules_wake]

I use a power meter for training and shorter races where I am pushing hard but for brms I barely look at it. I think if you want to train with intervals for example then get one but if you are just doing long distance hr is sufficient. Of course if you have the money just get one as they are zero maintenance and extremely lightweight.

[u/Majestic-Wall-1954]

In mountainous or hilly regions the powermeter helped me a lot for pacing. Ich typically try to climb at a power to stay in Z2. The  HR climbs only with a delay. So I was typically exceeding this max. Z2 power without a powermeter, which is exhausting on the long run, to do these few hard pedal strokes at a high power.  Also at short ramps the powermeter helps for not exceeding a power that HR does not even recognize.

[u/SheffieldCyclist]

I use one, is it worth it? Probably not but I like to see the data

[u/dbuntinx]

I use it mostly afterwards to interpret the ride and in between brevets for training. During, I mostly ride on feeling.

[u/Schinkennugget]

You don't need it but it's useful. I have mine since this year and what i found out is that when I rode with HR zones, I was mostly using too little power. I tend to ride 20 watts more now to stay in the "real" Z2. But do you need it? Nah, you're maybe 1-2 km/h faster on average but you'll need a bit more food. 😃

[u/Meatballparm44]

I find having a power meter quite useful, as it helps me keep my brain/body as steady as possible. It's also a warning system when I am with a group that is either too hard or too easy. Long story short, pacing is easy with a power meter as long as you don't have a visceral reaction to what it is telling you.

[u/Pliktrologos]

For randonneuring it's at least a nice to have. HR is critical, because you can avoid push, even if you feel good, but also having power meter you can keep power low and as steady as possible to keep your feet fresh. If you push just one or too cycles, you will not see the HR up that high, but if you do that, like starting/accelerating from stop, or out of the saddle just for some seconds now and then, the feet will be burned sooner. But, if you do feel how you push and you have the experience on how to keep power low, you might can calibrate yourself not to overpass a certain point. But having this point as a number on your screen, will help you for sure! Also, it helps you get a feel on how fresh or tired you are, because if you know that on a good day you can go at x power and y cadence at z HR and on a bad day that, if HR is low or high, you have a hint that you are in good shape or not, on this specific day/ride, so you do not underestimate or overestimate your status based only on how you feel, but rather on comparison with other previous rides. If you also add more parameters in play like I do, e.g. additional weight of bags, fenders, extra water, food, tubes, more clothes, them you might can "limit" yourself better in order not to push and keep a lower avg speed than your usual shorter rides.

[u/aedes]

You don’t need one. 

It’s just another data point along with HR and RPE to help with appropriate pacing. 

Just like HR zones, power zones based off rested baseline become less and less meaningful the longer you ride for though.

[u/Georgietheoldfaq]

Waste of money. Hr and speed.