Left Right Power Meter
 

At a recent bike fitting it was recommended that I would benefit from a power meter to address some left-right leg imbalance issues that are causing some ongoing problems. I know nothing about power meters other than skimming an occasional review over at DC Rainmaker and browsing a few posts on various bike forums. One thing I believe I remember reading is a comment that the PM data is most useful after a ride when it can be examined in detail. That is not so useful for my purposes where I am trying to monitor the difference in left and right leg power output and correct my pedal stroke to address this ongoing imbalance in power output. I don't even know if a head unit displays LR power or just total power.

During a ride, f I want to be able to observe sustained power power out put for each leg, can I see that real time in a head unit or will that data only be observable after a ride?

Thanks

The Edge 520 will show data for left and right power with several different power data field options on the head unit. I am pretty sure the Edge 1000 and the new Edge 1030 will do the same.

You probably want a pedal-based meter, although a crank meter might work, too. Look into PowerTap P1 and Garmin Vector, either will measure power from each leg independently.

P1 has the advantage of using either Bluetooth or ANT+ which means you can probably use your phone instead of buying a head unit, especially if you only want to see your data after you ride, not during. They’re also a little bit easier to install.

Vector might be better for you, in that it will also measure where you’re pushing on the pedal. That may or may not be relevant to your fit issue. Vectors only use ANT+, you might be able to find a phone app if your phone supports ANT+ (higher end Samsung phones do), but it’s more likely you’ll need to buy a head unit to use Vectors. These can be had for less than P1s, Vectors retail for $1,000, REI does a 20 % off sale occasionally and the pedals qualify, some places will just match the discount price if you point this out when you ask.

The way all the head units I’ve used and the PC software display the data is total power, and % contribution from each leg. People typically record this on a per-second basis, and if you wanted to reconstruct your sustained power from each leg, you’d be able to do that with software. What you’ll be told at the end of a ride is you averaged 240 watts, with 48 % from the left leg and 52 % from the right.

Shoot me a PM if you’d like some data from Vector 2 pedals.

Vectors 2
 

I been using vectors 2. And I swear by them. The left right balance is very helpful

An alternate inexpensive and effective old school method to develop a fluid, well balanced and powerful pedaling technique is to ride a Fixed Gear on the road as part of your program. Any imbalance or hitches in pedaling technique will be immediately apparent and smoothed out via negative/positive reinforcement in a simple relentless feedback loop with no batteries required.

-Bandera

Thanks for the suggestion about the Vector's and the P1. I have a Garmin 500 that I have delayed changing to see which replacement unit will work with a L/R power meter. The ideal thing for me is to have a viewable screen that displays total power and L/R contribution during the ride and then software that plots the L/R contribution to total power over the entire ride so I can see if I am correcting the imbalance in just some places but not others. This is in conjunction with doing strength work and working with the fitter to correct some long-term muscle memory issues where one leg is getting used more and as a consequence there are multiple tendon/muscle issues that keep recurring.

Looked at both and the P1 is appealing other than the keo cleat part of it.

@metalheart44 I have had an Edge 800 which is the same vintage as your 500.

It will display total power (from both legs combined) and L/R contribution as a percentage, in real time, as you ride. For example, like this:

279 w
49 / 51 %

I would be shocked if your 500 can't do the same.

A newer head will display the same thing.

Golden Cheetah is free desktop software, it will let you get at the second-by-second data and get it into Excel for you. Then you can plot power from each leg over time.

Good thought. I rarely ride fixed any more, but I learned a lot the first year I had it. I think I still have the benefit of that learning, many years later.

Why is pedal based better than crank based, if we are talking about L/R crank PM's?

Oddly enough Cycling is a Pedaling Sport.
My first coach had us work on pedaling technique before any other skills and returned to it each season.
FG base miles on restricted gearing was used to develop the muscle memory for a smooth, supple well balanced style w/ both grunt and spin on demand. Once learned at the neural/muscular level never forgotten entirely.

Does an electronic metric-box provide instant/constant physical positive/negative feedback on pedaling technique on a FW machine?
Sometimes the simplest low cost old school techniques are still appropriate.

What's the real question that the OP is asking?

How to functionally "address some left-right leg imbalance issues " and improve/eliminate the L/R imbalance?
or "What gizmo displays real time L/R power and captures the data?"

PS: Rollers: riding rollers (especially on a FG) will provide excellent feedback on any hitches in pedaling technique right away.
A great inexpensive tool that requires no 2nd machine or other gizmo for neural/muscular training, and so very old school.

As always, suit yourself.

-Bandera

It’s been a while since I’ve done my research (because I settled on Vector 2s) so a few of the details are hazy, but:

* Pedal based meters put the pressure-sensors in the pedals. Obviously. Garmin and PowerTap both make models that have sensors in both pedals, like the OP requires.
* Crank-arms would work, too, but I don’t know of any bilateral crank-arm power meter. You can get a left-only one from several companies, but the OP needs to measure both legs.
* Cranks themselves don’t actually know what leg you’re using. They assume the power is coming from whichever side has the arm forward, or up. That assumption is going to work most of the time, but the OP needs this to gather data to resolve a medical issue. Most of the time may or may not cut it.

Your advice requires two extra machines, and the space to use and store them: rollers, and a FG bicycle.

The OP is asking for tech details to inform a purchase. This is after consulting with a medical professional.

Most of us in here aren’t medical professionals. None of us knows exactly what the OP’s malady is. None of us have examined the OP. Nobody in here has a leg to stand on, second-guessing the OP.

Thanks for the fixie and rollers suggestion, but after discussions with two different fitters, a PT, and my cyclist ortho doc, it seems a L/R power meter is the best option for my situation. The medical details related to the imbalance and its consequences are too long to relate, but the issue is that it is an ongoing problem that I am addressing with PT and an off-the-bike exercise program to avoid one more surgery. In the long run, it seems a power meter also offers some training benefits once I get the other issues under control. Thanks again for the comments.

Garmin Vector just became more attractive: https://www.bikerumor.com/2017/09/08...gps-computers/


Cheaper than before and no more dangling external transmitter.


I'd probably still go with the Powertap P1s, but now it's a closer battle.

There's still no SPD pedal power meter, is there?

Not in the mix. Of the ones frequently mentioned......

Vector 3 --- Uses a Keo style cleat

Powertap P1 --- Powertap adapted Keo style cleat

Favero Assioma ---Favero original/Look

Garmin said an SPD version was in the works before they released the original Vectors (that they bought), but I haven't heard a word about it since. I would have preferred an SPD one, but made the switch for a pedal-based power meter.

The Keo cleats can be an issue if you ride through mud and get off the bike.