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2015-12-11 11:21 AM

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Subject: Power meter (for dummies) questions
I'm a gadget guy. I'm also working my butt off on the trainer, with no metrics to show for it. I'm wondering if a power meter is right for me?

1. How much is a "good/adequate" PM?

2. What does a typical head unit look like? What metrics does it track?

3. Assuming I keep a constant tire pressure and trainer (fly wheel) setting, can I expect usable information?

4. If you run a PM, do you still run a cycling computer (ex - Garmin 500 or the like)? I'm guessing the answer(s) to the second part of question no. 2 would answer this, but I don't know.

5. If I'm only planning to run a 70.3 or two (for the foreseeable future), does it make sense for me to purchase a PM?

Thanks


2015-12-11 2:54 PM
in reply to: nc452010

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Subject: RE: Power meter (for dummies) questions

Originally posted by nc452010 I'm a gadget guy. I'm also working my butt off on the trainer, with no metrics to show for it. I'm wondering if a power meter is right for me?

You can experiment with virtual power as long as you have a speed sensor on your rear wheel while on the trainer and have an ANT+ stick for a PC or laptop.  Golden Cheetah can convert speed to virtual power for free, apps like trainer road have a monthly fee.  Pretty much every major trainer has a power curve loaded into these apps.  It may not be 100% accurate, but for trainer purposes, it should be sufficient to set workout targets and track progress.

 

1. How much is a "good/adequate" PM?

I would consider a good PM as one that measures total power.  Not measures one side and doubles it.  Right now, the cheapest brand new options are a Powertap built into a training wheel or a Power2Max.  Both will run you around $600-700.  Other used options can get you in the sub $500 range...even down to the $200 range if you can find an old wired Powertap.

 

2. What does a typical head unit look like? What metrics does it track?

Typical head units include the Garmin edge line (500/510/520/800/810/1000), the Garmin Forerunner XT line (310/910/920), Cycleops Joule, as well as a several other brands like Wahoo, etc.  Usually run anywhere from $150 and up brand new.

 

3. Assuming I keep a constant tire pressure and trainer (fly wheel) setting, can I expect usable information?

For virtual power, keeping consistent tire pressure and fly wheel resistance is the key to getting usable information.  If you're running a real power meter, it doesn't matter.

 

4. If you run a PM, do you still run a cycling computer (ex - Garmin 500 or the like)? I'm guessing the answer(s) to the second part of question no. 2 would answer this, but I don't know.

Yes, you need to run a cycling computer capable of reading power information.  A power meter itself only transmits power info to a head unit.  It does not store that data anywhere within the power meter itself.  IOW, without a head unit, a power meter is completely useless.  Not all cycling computers can read power data.  The lower end ones like the Garmin edge 200 or the newer edge 20 and 25 cannot read power.

 

5. If I'm only planning to run a 70.3 or two (for the foreseeable future), does it make sense for me to purchase a PM? Thanks

A power meter is simply a training tool.  If used properly, it can help you guide your training and racing, but it is by no means necessary.  You get out of it what you are willing to put into it in terms of your own analysis and tracking (post ride) as well as your commitment to use the numbers while riding.  Some people prefer to ride without distractions of their computer and go by feel.  Some people when they are done with a workout do not like to upload the data and analyze what they just did...or what they have been doing for the last 3 months.  Those people it would not make much sense for them to invest in a power meter.

I would advise everyone thinking about power to first read up on one of the few books that are out there.  Allen & Coggan, Skiba, or Friel's books.  Then experiment with virtual power for a few weeks/months.  If you're "into it," then you're probably a good candidate for a power meter.

2015-12-11 3:29 PM
in reply to: nc452010

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Subject: RE: Power meter (for dummies) questions
Originally posted by nc452010
1. How much is a "good/adequate" PM?

2. What does a typical head unit look like? What metrics does it track?

3. Assuming I keep a constant tire pressure and trainer (fly wheel) setting, can I expect usable information?

4. If you run a PM, do you still run a cycling computer (ex - Garmin 500 or the like)? I'm guessing the answer(s) to the second part of question no. 2 would answer this, but I don't know.

5. If I'm only planning to run a 70.3 or two (for the foreseeable future), does it make sense for me to purchase a PM?


1. Power meters keep dropping in price. You do need to decide whether you want left leg only (like stages) total power (like power2max) or the ability to show both left and right leg power (like powertap P1). The other thing would be whether you want to run the PM on multiple bikes, in which case a hub-based PM (i.e. powertap) would be easiest. Power2Max seem to be pretty reliable and start as low as $610 I have one and have had no issues with it. The only other PM in the same ballpark for quality/price ratio would probably be Quarq, and it's more expensive.

2. You don't usually need a head unit. Pioneer's head unit allows you to see more metrics. I know SRM and Powertap has their Joule units, but most people just use their normal computer (like Garmin - I use a 310XT with my P2M). What they track depends on your power meter (i.e total power vs right/left power) and you can display a few different things (current power, 3s power, average power, etc.) The data is both useable in real time (for pacing, or hitting targets) and as data to analyze after the fact (on your computer).

3. You don't have to maintain constant tire pressure and flywheel settings. You put out the power you put out.

4. Answered in #2

5. Up to you. They're expensive for sure. But I've found that it really helps with training (particularly when combined with something like Trainerroad) and also with pacing in a race. It's remarkable how different pacing with RPE is from pacing with power. If you've got the money to spend and are debating what to spend it on, I don't think there's really much of a question that the PM is going to get you the most speed/$ if you use it properly (as opposed to aero wheels or new aerobards or something). But there are plenty of fast folks out there who don't train or race with power. Whether it's an expensive toy or a valuable tool is totally up to you.
2015-12-11 5:21 PM
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Subject: RE: Power meter (for dummies) questions
Thanks guys. I already have a Garmin 510. I also already have race wheels. So, I'm just guessing I wouldn't want a hub style PM? Don't they make PM's that are crank arm models? Would I simply replace the current crank arms.............and are the PM's pretty universal (work with any crankset)?

Thanks again.

Edited by nc452010 2015-12-11 5:21 PM
2015-12-11 6:00 PM
in reply to: nc452010

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Subject: RE: Power meter (for dummies) questions
If you want to use your PM on different bikes, then having a powertap laced wheel makes it easy to switch between bikes. Switching pedals (as in a P1) isn't that hard either. If your power meter will only ever be on one bike, then switchability isn't really a consideration and you can go with whatever.

They do make PMs that are crank arm models (stages) but if you look into it you'll see there may be accuracy issues. Up to you whether that's a concern or not. Realistically consistency should be of greater concern than accuracy, but given potential L/R power imbalances it's worth taking into account.

For crank-based PMs (like Power2Max or Quarq) the bottom bracket standard of your frame will dictate what specific model you end up with. Some powermeters might be direct plug and play, some might require a new BB.
2015-12-11 6:17 PM
in reply to: #5156181

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Subject: RE: Power meter (for dummies) questions
Hey NC. Go check out dcrainmakers piece about powermeters. It will give you a headache but he is really thorough. Just Google dcrainmaker power meter and it should be the first hit. He is fine with single sided power unless you have some reason to think your left and right power output is different, and even so, as a training tool, what does it matter as long as it is consistent?


2015-12-11 6:18 PM
in reply to: nc452010

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Subject: RE: Power meter (for dummies) questions

Stages ($580 Ultegra 6800 arm) and only measure power on one (left) arm. looks like they can be found on eBay for under $500.

Pioneer is way over priced for its dual arm model.

Not sure of any other arm based units (yet).

2015-12-11 6:28 PM
in reply to: louiskie

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Subject: RE: Power meter (for dummies) questions

Originally posted by louiskie He is fine with single sided power unless you have some reason to think your left and right power output is different,

Most people do not know if they have any type of L/R imbalance until they actually test it, over time, with a power meter that can measure L and R independently.  IOW, you don't know if you're a good candidate for a Left only PM unless you first do thorough testing with a dual sided PM.

and even so, as a training tool, what does it matter as long as it is consistent?

Tied into the answer above, it doesn't matter if your PM reads and consistently doubles your left leg if your L/R balance is not always the same.  That is the one thing people don't fully understand.  They can grasp the concept that one leg is stronger than the other, but can't grasp the concept that their L/R balance isn't the same all the time.  

Studies have been done to prove that in many riders, L/R balance can vary.  Not just based on given efforts, but day by day and within the same ride.  IOW, at 200 watts you might be 52/48, but at 300 watts you might be 50/50.  On days where you had rest that might change to 49/51 and 47/53 respectively.  Or at the end of the ride your L/R balance might be different than the beginning of the ride for the exact same effort level.

 

2015-12-11 6:45 PM
in reply to: #5156260

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Subject: RE: Power meter (for dummies) questions
Good points Jason. My question though is, in reality, for most people, what is the real practical application of that? Does it justify paying almost twice the price to know the left right balance? I'm actually really curious because I'm looking into getting a powermeter as well. I'd guess that most of us would do a field test to set our training and racing power thresholds. And then you train and race. Would most people really go deep enough to care that, at 200 watts their balance is different than at 300 watts? Would they really change what they do?
2015-12-11 8:34 PM
in reply to: louiskie

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Subject: RE: Power meter (for dummies) questions

Originally posted by louiskie Good points Jason. My question though is, in reality, for most people, what is the real practical application of that? Does it justify paying almost twice the price to know the left right balance? I'm actually really curious because I'm looking into getting a powermeter as well. I'd guess that most of us would do a field test to set our training and racing power thresholds. And then you train and race. Would most people really go deep enough to care that, at 200 watts their balance is different than at 300 watts? Would they really change what they do?

18 months ago when the cheapest total power option (that wasn't hub based if you had race wheels already) was over $1100...yes, you could say something like stages for $600-700 might be "worth it." to you.  In today's market, where you can get a brand new Type S P2M for $610, I don't think there is a real practical reason to save $100 for single legged power.

But even if there was still a significant price gap, take this hypothetical example.

You invest in a one sided power meter like Stages.  You do some preliminary testing where your FTP is determined to be 250 watts.  You have no idea that during your test you were averaging 53/47 L/R...all you know that is your left leg was pushing 125 watts and it doubled to 250.  In reality though, if 125 watts is 53% of the total, then the total really is ~236 watts.  125 left and 111 right.

Okay...if your L/R balance is 53/47 all the time, then no problem.  Unless you're doing aerodynamic testing...but in lines with your question about "practical applications," let's assume you're not interested in that.  So lets say you do some training now on longer efforts in prep for a HIM.  Something like a 3 hour ride with 3x30' intervals targeting 200 watts (80%).  The first interval is you're at 53/47, the second as you fatigue you move to 51/49, and the last interval you drop down to 49/51.  

Here's the problem though.  You're basing these interval targets on the fact that your FTP is 250 when it is really 236.  The first interval you're left leg is pushing 100 watts and your right leg is pushing 88 watts for 188 total.  You're computer reads 200 watts since it's doubling the left leg.  No problem though, because 188 is still 80% of 236.  The last interval though your left leg is pushing 100 watts, and your right leg is pushing 104 watts for 204 watts total.  Your computer is still reading 200 watts because it's doubling the left leg, but now even though you "think" you're holding 80% of FTP, you are really holding 86.4% of FTP (204/236).  

You have no idea why the last set is absolutely killing you and you blow up.  You start second guessing yourself.  Then you see more variations in how easy or hard your workouts are because your L/R balance is varying and you don't really know how to predict it.  But lets say you do get a hang of it during training...maybe.

Then on race day...when you're all tapered up...your L/R balance might do something totally different that you have not experienced in training because you rarely train tapered.  Maybe it will start at 49/53 and move to 53/47?  Who knows?

-----------------------------------------------

Think about this for a little while.  Why would you invest ANY MONEY in a device that may only complicate and frustrate your training.  You'd probably be better off just using RPE and or HR than trying to analyze data that assumes your L/R balance is constant...when it most likely is not...nor is it very predictable unless you have a L/R power meter to confirm it.

I myself would NOT use a left only PM to train with even if you gave it to me for free.  Heck...I probably wouldn't even use it if you paid me $200.  I have almost 6 solid years of power data that I can rely on and compare to.  A left only PM would not only confuse me going forward, but pretty much trash everything I had in the past as I can't trust the comparisons to be apples to apples.

This is just my take on it.  I'm sure there will be tons of people who say they use their Stages just fine and it works for them.  There will be other people who cite the Bradley Wiggins and Chris Froome did this and that using a Stages.  To each their own.

2015-12-11 11:17 PM
in reply to: nc452010

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Subject: RE: Power meter (for dummies) questions
Originally posted by nc452010

I'm a gadget guy. I'm also working my butt off on the trainer, with no metrics to show for it. I'm wondering if a power meter is right for me?

1. How much is a "good/adequate" PM?

2. What does a typical head unit look like? What metrics does it track?

3. Assuming I keep a constant tire pressure and trainer (fly wheel) setting, can I expect usable information?

4. If you run a PM, do you still run a cycling computer (ex - Garmin 500 or the like)? I'm guessing the answer(s) to the second part of question no. 2 would answer this, but I don't know.

5. If I'm only planning to run a 70.3 or two (for the foreseeable future), does it make sense for me to purchase a PM?

Thanks


all your bulleted questions have already been answered, so I'll skip those. I'll just add that a power meter is not a necessity. I'm as gadget oriented as anybody and a PM can provide good guidelines for training, good records of the training actually performed and a good measure of objective improvement.

But you can still get all of that without a PM with the use of HR and / or RPE. Trust me I have come full cirle on this. There was a time I would not coach someone without a PM and could not imagine someone improving signficantly in cycling or triathlon without using one. Then I used them a ton for myself and for my athletes and we all got so sucked into the numbers we forget how to listen to our bodies.

More recently I've coached athletes who do not own a PM and I work with them to really listen to their body and use HR as a guideline or virtual power (expecially good on trainer/test days).

But the athlete of mine who is the fastest by far and has the most podium wins does not even use a PM...and we rarely refer to her HRM except to track work already done.

So if you want one, get one, they are fun. If you are htinking of getting one because you think you need one to get better...save your money. If you think that having one will imrpove accountability and motivation...then that's a decent enough reason to buy one as well. But you don't need one.


2015-12-12 3:33 PM
in reply to: Jason N

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Subject: RE: Power meter (for dummies) questions

Here is a graphical representation of some of the issues with left only PMs that Jason describes.  This is a graph of a workout I did (on the trainer) that included two intervals (you know, Z2 350w intervals   where i shifted gears in the middle.  Blue is cadence, yellow is power, red is left/right balance (above the line is left, below is right).  You can see in both of them that when i shifted from a higher cadence to a lower one, my left/right balance shifted from right dominant to left dominant.  If I zoom in and look at the specific numbers for the two cadences, at the high cadence a Stages would report ~8w low and then when I go lower cadence, it would report 10w high.  That's an 18w swing even though my actual power is within 1w.

2015-12-12 9:46 PM
in reply to: axteraa

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Subject: RE: Power meter (for dummies) questions

Wondering how many end up pushing the left leg more over time.

2015-12-16 3:44 PM
in reply to: nc452010

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Subject: RE: Power meter (for dummies) questions

OK Jeff, what are you going to go with/do?  I see you dumped the 6800

2015-12-17 7:49 AM
in reply to: Donto

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Subject: RE: Power meter (for dummies) questions
I still don't know. I actually still possess the 6800, too......lol.

2015-12-19 12:12 PM
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Subject: RE: Power meter (for dummies) questions
Power meters, heart rate monitors, speed and cadence sensors, etc...all this technology is great, it helps us analyze our efforts and see where improvements are being, and can be, made. I'm a big fan of pouring over every tidbit of data to see what's going on...the more, the better.

That said, we often forget that greatness was achieved long before any of these things existed.

Do they help? I have no doubt.

Is the very latest, most high tech gadget going to make or break your performance? Almost certainly not. It's still 99% discipline, training, and effort that takes you across the finish line.

Every individual is different, your training time, personal "style," equipment, and of course, budget, all affect what gear you wind up using. If you can afford the best, and will be able to use it to your advantage, by all means, go for it. If you, for whatever reason, decide on "less than" the "newest and shiniest," I don't think the overall net result will be radically different.

A power meter is a big help. In my personal opinion, it's one of the better investments for a serious cyclist/triathlete. The difference in a used, wired Powertap and a top of the line, ANT+/Blutooth GS hub that logs to your Garmin is a great deal of convenience, a bit of extra information...and several hundred dollars. Separate left/right power readings is another type of somewhat pricey, but marginally effective in the overall picture, upgrade.

It's all about finding your own, personal "sweet spot."

Just my opinion, yours may vary.





Edited by dpd3672 2015-12-19 12:13 PM


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