Thinking about buying a Stryd power meter. What are the pros and cons?

Waste of time and money. Get a Garmin Forerunner and you will be much better off

I really liked the idea for trails and some treadmill use of having accurate measurement. There is a mtb single track that has been measured and has post marking every .25m. I have ran it clockwise and counter clockwise multiple times and the stryd measured within .05 every time, but it was short around 5% every time. You can calibrate it, but the whole reason of me buying it was bc they advertise it's so accurate out of the box.

They have instructions on how to calibrate it using a 400m track. I emailed them in detail asking them a few questions, and got a standard copy and paste reply that was of no help, and it also said they do not guarantee accuracy. All of their advertising is based around how accurate it is supposed to be. Another guy I talked to loves his and on that same trail measured pretty much perfectly out of the box. I have calibrated mine, but really don't trust it at this point.

Pros: it's only $219, less than VFs

Cons: it's complete bollocks

I have used the old and the new footpod.

Pros:

1. It's great for maintaining consistent effort on hills or, for the new one, in wind.

2. I have had success recording consistent pace/distance in areas with less than ideal GPS coverage. Buildings, trees, etc. Also treadmills. You can debate whether it works better for this than a generic Garmin footpod.

I have not had any issues with auto-calibration.

Cons:

1. Expensive

There's plenty of debate on the use of power in training/racing versus heartrate. The draw behind power meters is that you are measuring purely mechanical power output based on motion, whereas heartrate is affected by so many other variables like heat, hydration, terrain, sleep, nutrition, menstruation, stress, caffeine, altitude, the list could go on all day. So it's an exact measure of physical effort.

My position is that all those other things actually matter. We say to listen to your body and your heart is part of your body. You're not going to put put the same watts for the effort in lousy conditions.

So if you're interested in a new toy to give you some extra data that can be useful in certain situations, go for it. Just don't become a slave to it any more than you would become a slave to any other running gadgets.

accuracy can be frustrating. its on their website but not out there enough, 1 footpod to the other can be off up to 3%.

I calibrated mine on a track today as per the website and had to change the correction factor to 102.4. So closer to the 3% off out of the box. Very consistent, but frustrating when you are running with another person who also has stryd and your lap splits are out of sync.

Cyclist been using power meters forever now. So why don't runners?

If you already have a Gamin then just get the Garmin footpod.

I have a Stryd, but I bought it because I already had an Apple Watch and GPS wasn’t reliable in central Tokyo. I would’ve bought a Garmin footpod if I still had my Garmin.

Don’t they only ship to the USA?

Calibrated Stryd is the best way to have pace as accurate as possible.

Much more accurate than GPS. The rest (metrics, power) for me is just an icing on the cake.

Proof:

https://fellrnr.com/wiki/Stryd#Testing_Distance_and_Pace

I think it would be a fun gadget, and a new data stream to analyze and learn about. But the body of knowledge about what to actually do with your Stryd data, and how to use it to inform your training, is pretty slim. Where the tech stands, if you change your training based on your Stryd data, I couldn't tell you if it would help or hurt you.

If it's something fun that will add joy to your running, I'd say go for it. But if you're looking to draw reliable conclusions, I'd move on. I see this as just a first step towards an analog to a bike power meter, which is probably why Stryd was able to get funding in the first place. If reliable running power meters are made in the future, it will be in part because of what we learned from Stryd. We didn't land on the moon with Apollo I - but that mission didn't promise to bring us there. Stryd is kind of uhhhhh fudging in this way - promising to take you to the moon, when who knows where you're going.

Stryd's best feature for me (by far) is the race calculator.

After you feed the system with 1-2 months worth of solid training (intervals/tempos/long runs) and racing data you get a single number in watts to follow when racing. This number in watts is specific for 5K-10K-marathon etc.

As long as you keep very close to that number when racing (regardless of terrain), you are racing at or very near your current full potential while minimising the risk of going out too hard and not being able to perform as expected.

Think of it like Garmin's PacePro feature but much more advanced as it is calculated in real time.

I was considering a Stryd but then I stared looking at the running dynamics pod from Garmin. I know my 945 does candence but has anyone tried the Garmin and find it useful?

I work at Stryd, so feel free to ask any specific questions.

I have transitioned to only training by power and it's extremely rewarding to be able to actually track progress and know your exact capabilities for workouts and races.

When using Stryd, you'll get your threshold auto-calculated based on your workouts and runs you're doing. This Threshold will adjust over time based on the data you're feeding into the system. The Threshold number is included in a Stress Score for each run, which then gets put into a Performance Management tracker.

A complicated way to say, the system tracks your fitness, helps you see how stressful sessions are, and helps you mange that stress by letting you know your current state.

Like others have said, the distance and pace is super accurate and precise. You might have to apply a slight calibration factor, but the steps are very easy to do so. I can't imagine trying to just guess about my training day to day going off of pace or heart rate.

Power is an objective measure of your effort and extremely helpful to inform you of exactly how hard you're working in real-time.

And like I said, any specific questions I'd be glad to answer!

behind the wall of sleep wrote:

Cyclist been using power meters forever now. So why don't runners?

I could write you a lengthy novel on this, but let me try and condense.

TLDR:

-Bikes have a logical place that you can place a sensor and actually measure power, while a runner does not.

-Biking involves a single, simple, repetitive movement. A running stride is made up of distinct phases, and there is a ton of variability in form between individuals.

Main reason bike power meters are popular: on a bike, there is a logical place where a single sensor can accurately measure the mechanical power coming from the cyclist's feet - measure the crank arm deflection to get the force applied, then multiply by the speed their pedals are spinning...that's really mechanical power. There is no such place on a runner that we could measure mechanical power. Stryd attempts to infer mechanical power by measuring the trajectory of the feet through space (using really high-quality accelerometers and gyroscopes), and adding in the effects of wind, which it also measures. That's just not a direct measurement, and we didn't have the right tech to build something like Stryd until recently. It's very sophisticated and finicky. The difference between running and biking here really boils down to running being a much more complex movement with distinct phases, not just a force going around in a circle.

Then there's the training aspect. When a rider applies mechanical power to bike pedals, there is a predictable relationship to how much metabolic energy their body consumes. This is an extremely useful link for targeting metabolic work rates using a mechanical power meter alone. That's actually the basis for TrainingPeaks' TSS - it applies a 30-second running average of mechanical power (from the bike meter), to try and infer the metabolic response. Power-based bike training is only possible because you can infer the metabolic response. And that's why bike meters are popular - because of the nature of the activity, bike meters actually give you real the real information, without caveats.

This relationship is not so straightforward with running. That's why form matters - if we have two runners consuming the same amount of O2 (same metabolic power), the one with better form will end up moving faster (better mechanical power, or better efficiency of conversion). This is one of the biggest barriers to creating a meaningful analog between biking power and running power - the metabolic component behaves differently.

Hey forcerunner, thanks for popping in! One big question I've had on my mind:

Is the intention of Stryd to measure mechanical power only? With cycling, it's easy to just multiply mechanical power by 4 (or divide by the efficiency factor 0.25), but running is not so simple. From what I've read, it seems like Stryd is sticking to the domain of inferring the mechanical forces generated by the muscles, and is steering clear of inferring any type of metabolic response. Is that a correct summary?

By the way, auto-calculated CP threshold is wildly inconsistent if you're doing any kind of periodization.

I've been consistently gaining fitness last 3 months, progressing from base kind of training to adding some workouts throughout that period. In short, I've been doing all the kinds of workouts that Stryd recommends for correct auto-calculation.

My CP changes:

18.03 266 -> 272 (+2%)

24.03 272 -> 265 (-3%)

01.04 265 -> 266 (+0.4%)

13.04 266 -> 261 (-2%)

17.04 261 -> 262 (+0.4%)

21.04 262 -> 255 (-3%)

24.04 255 -> 287 (+13%)

My real CP was improving all this time! It seems to be very sensitive to individual workouts

Didn't find it accurate with hills.

Is an "extra" item to attend when getting ready to run, especially if have more than 1 pair of shoes.

Because cycling technique is roughly identical between cyclist, cycling powermeters more measurable and accurate.

But there are a lot of cool people in the running and triathlon world playing around with the data Stryd provides. The Stryd community is lights-out. So I think if use with more flat/standardized workout or on treadmill, you may find it an very useful tool with an even more useful community of users/coaches.

Would be interested in knowing whether Stryd might be able to predict if you are a VaporFly responder.

Trail Zealot wrote:

Hey forcerunner, thanks for popping in! One big question I've had on my mind:

Is the intention of Stryd to measure mechanical power only? With cycling, it's easy to just multiply mechanical power by 4 (or divide by the efficiency factor 0.25), but running is not so simple. From what I've read, it seems like Stryd is sticking to the domain of inferring the mechanical forces generated by the muscles, and is steering clear of inferring any type of metabolic response. Is that a correct summary?

Yeah that's a great question. There is a full white paper on the exact methods and explanation on how this is calculated:

Basically, Stryd is aiming to measure the positive mechanical energy. The paper goes in depth on it, but even with Cycling power meters, the force is applied from the foot, then the power is calculated by the motion and velocity of the crank, not directly measured.

Since running is a much more cyclical and dynamic activity, you have to calculated forward power and vertical power, and with the most recent version, the extra metabolic work needed to overcome air resistance.

Darby wrote:

By the way, auto-calculated CP threshold is wildly inconsistent if you're doing any kind of periodization.

I've been consistently gaining fitness last 3 months, progressing from base kind of training to adding some workouts throughout that period. In short, I've been doing all the kinds of workouts that Stryd recommends for correct auto-calculation.

My CP changes:

18.03 266 -> 272 (+2%)

24.03 272 -> 265 (-3%)

01.04 265 -> 266 (+0.4%)

13.04 266 -> 261 (-2%)

17.04 261 -> 262 (+0.4%)

21.04 262 -> 255 (-3%)

24.04 255 -> 287 (+13%)

My real CP was improving all this time! It seems to be very sensitive to individual workouts

Sorry for the double post, but I imagine this reason, is due to certain activities dropping out of the 90 day window for consideration, and the adjustment due to the Anaerobic Work Capacity.

If you're periodizing your training, you're most likely going to be adding intensity as you go on, but the specific addition in your training would be helpful to know here!

Lets say you have this progression of workouts:

April 17 - 10k tempo at 260-265W. Your CP bumps up slightly because this is the longest duration you hold this power for in the last 90 days.

April 21 - You do some 200s or 400s and crank the last one. You push up your short duration contribution, AWC, and it drops your overall CP because of the modeling used.

April 24 - You do a hard 10k at 285-290W and this pushes your CP back up.

The modeling using for calculating the CP value looks at the contribution from three different energy systems, and in turn three main different types of activities.

Your short duration, medium duration, long duration.

If you increase your short duration, and the medium/long stay the same, it is assumed that all values reported at maximal. This would, in turn, push the overall CP value down as the contribution to the model is changed.

There is actually a super cool feature in the online platform, PowerCenter, which will let you see your modeled curve, so you can see if you do have a large drop-off or plateau at certain areas. I hope this explanation helped a bit, but would be glad to explain further!