I was wondering if anyone has any thoughts about additional value provided by dual sided power meters.
I’ve seen left-right balance discussed previously, and it sounds like this is only typically applicable after an injury. Are there other benefits aside from left-right balance?
For example, does total power give any noticeable difference in accuracy vs doubled-up power from one side? I could imagine this giving benefits for measuring the timing of short high powered intervals. But then again, I could also imagine it just not making much of a difference in practice.
Does anyone have experience with both one sided and dual sided power meters and whether there were any benefits that might make the extra expense worthwhile?
I had single sided 4iiii and then upgraded to dual sided. The info I see is that the balance will swap back and forth and in general I do not see a huge difference. That said I do believe that there is some bias to single sided reporting and it really depends on so many things related to you as an individual. What I mean is that you may be biased one way at low power, more balanced at another and still biased the other way at say sprint power. Also you may exhibit different bias as you fatigue. With single sided it will not account for that. However depending on a lot of ifs, the single sided will likely always exhibit that same set of biases and the real benefit of a power meter is not to compare to other but to compare to yourself day to day, month to month etc… so if close is good enough that is the accuracy question, consistent reporting is the precision question. I think that the 4iiii are quite precise devices. So if your budget allows for dual sided go for it. The nice thing is you can upgrade almost every branded single side to double side down the road so it is not that big a deal in the long run. Personally I am a data geek and love to look at the l/r balance while I train to see what is happening in real time.
Thanks, Ron, for your perspective. Part of the reason I’m asking is that I’ve heard bad things about power meters on right-side Shimano cranks, so if I think I will want to upgrade to dual-sided power later, I might lean towards a pedal power meter instead of a crank power meter.
I have seen some things on that, I think it is worse with Dura race I have 105 and it seems to be no problem, also there was something said also that I read (can’t find reference though) that 4iiii had come u with a workaround for the issue.
So for my set up and my level of concern the new 105 drive side works fine.
Hi Andrew, my Neo 2T measures both sides and the cycling dynamics function (although not fully implemented yet by Garmin) has shown my legs to be pretty balanced, with no prolonged bias. It’s given me confidence to invest in the Garmin Vector 3S one-sided pedal system so I can extend my direct power measurement and gain benefits of that for my outdoor riding rather than just autumn/winter indoor training.
I started with Powertap P1 pedals a few years back and life was great. Then last year the right pedal died and couldn’t be repaired. So Quarq recommended I use a left pedal only as a single sided power meter or they could discount a new Quarq DZero, but I would have to change my crankset and all. I stuck with the left side only pedal and life was fine.
Then I bought a new bike with a Rotor InPower single sided, then life got puzzling. Both power meters read exact with each other on the trainer, but on an outdoors ride the Rotor InPower reads 8-10 percent lower in longer efforts and around 20 percent lower in sprint type efforts.
Now the Rotor software will allow you program your left side balance if known. For around 3 years with both pedals working I was always 47-48 percent balance for the left side. My next step is to try programming that into the InPower to see what happens.
I say all that to say, I’m more of a proponent of dual sided power weathers its crank or pedal based. I wish I had went with some Favero pedals or something vs the single sided InPower. I think those sprint type efforts would be important for Xert.
I lived for a 7 years with a stages (on my training and all purpose workhorse) and and a pair of garmin Vectors (on my summer/racing bike). The former is still going, the latter is half dead (one pedal died last autumn). I have not seen any practical gain in my training or managing long term data from the dual sided power metre. I have seen though a good amount of curiosity satisfaction and a bit of extra confidence in the numbers.
I know by now I have a 2% imbalance (49/51) around lower threshold and tempo and it corrects as I am approaching and exceeding the threshold. Honestly, it does not make any difference. That would probably mean that the stages is showing 1% less (mounted on the left crank) which I am considering negligible.
I am planning on replacing my vectors with asioma duos when I will start riding outdoors again but if I would not hesitate to go for one sided, if I had to save a bit of a cost.
I have just done some testing over the weekend with my 4iii left only power meter and Kickr Core and have managed to get the two tracking at an average difference of 0.3% by adjusting the slop rating on the 4iiii which is good enough for what I need it to do.
Ideally I’d have dual, and I may one day end up with dual, but for an amateur like me I think its good enough.
There’s a couple of things in the two-sided vs single-sided discussion. The first question is do the metrics like leg balance etc. add anything and I think except for someone recovering from injury the current consensus is that nobody knows what to do with this information, so they are not really important.
The second part of the question is what type of power meter to use, there is essentially two type of powermeters in the single sided vs double sided space. There are the true left-right balance power meters, which are either pedal or crank based (stages, 4iiii, favero, garmin). They do measure your true left and right power, the down-side is if you buy a single sided version of these only it simply doubles your power to get your full power, I come back to that later.
The second type are the spider, BB, hub-based powermeters and trainers. While some of these give you L/R balance, they are not able to actually measure it they simply look at the different parts of your stroke and calculate the balance from that, there is general agreement that the metric is even more useless than the true L/R balance, because you don’t actually know where that balance is coming from (are you simply puling more with one leg or do you actually push more with the other leg).
Regarding a question what type of powermeter to get. The issue with estimating power from a single sided measurement is that you don’t know your actual balance and importantly your balance might change significantly with effort. Thus your reported power might be quite different at different effort levels to your true power levels, which can make intervals estimated based on e.g. FTP either harder or easier than they should be (somewhat less of a problem with xert).
A similar argument applies to the shimano dual-sided powermeters, which report wrong numbers based on pedal style (i.e. effort level), GPLama has talked about that quite a lot (watch his videos if you are interested).
What I would do is either go for a spider (quarq, rotor), or dual-sided pedal based or non-shimano crank based powermeter. I don’t think the small savings of a single sided version crank or pedal based powermeter (e.g. Assioma 450 euro vs 700 euro) is worth the inaccuracies. However, I would not care if you get true (pedal/crank-based) or estimated (spider/BB based) L/R measurements, go for the best deal you can get.
If you look for it at least in Germany you can get the Assioma Duo for 650,- Euro. With them now self calibrating and being so easy to install on any bike and easy to swap between bikes they are really good value for that. The accuracy and reliability is usually rated very high as well. There is just the lack of a ‘proper’ brand name. Just my humble opinion though, I like mine but YMMV.
I agree, currently assioma duo’s are hard to beat in terms of value for money, especially if you ride Look. I’ve also bit the bullet and bought a pair even though I love my time pedals (I ride campa so spider options (SRM, power2max) are so much more in price it’s really not justifiable).
