Is pedal based or crank based better for power meter?

Probably building up an S-Works SL8 so not sure will get the 4iiii crank arm power meter that comes with the full bike
Is the 4iiii power meter better than the Shimano crank power meter?

Any thoughts on pedal based power meters like Garmin Rallye or Favaro Duo?
I currently use Look Blade pedals (non power) and was also considering the power version

Thanks

All have their pros/cons. Suggest you look at YouTube reviews by DCRainmaker and GPLama for details.

Yes, definitely.

I have both the 4iiii Precision 3 non-drive crank arm on one of my bikes and the Favero Duo Shi(Shimano pedal bodies) on another. Either one works great, the pedaling dynamics data from the Faveros is interesting, but it wasn't anything that would cause me to change my training.

I have no personal experience with them, but the Shimano power meters don't have a great reputation. I also own the Garmin Rally pedals(in the SPD version for my gravel bike,) and I'm not totally stoked on them. The data seems alright if they are torqued exactly to spec, and I pedal around on them a bit before doing the whole reset and calibration process. In comparison, the Faveros just work without any special set up process.

Pedals move from bike to bike.

You can put them on a dumb trainer, use them if you travel and rent a bike…

I have dual sided Shimano road pedals and a single sided FaveroAssioma SPD (MTB) pedals.

For me, the extra cost of the dual sided pedals just isn’t worth it. And going forward I’m going to standardize on SPD/MTB style pedals vs road style.

Shimano hasn't a good reputation in terms of PM accuracy. I currently ride a SL8 Pro that came with left side 4iiii Precision 3+ PM and it's been flawless so far. I had two dual sided Giant Power Pro PM before that on my 2 previous bikes (both Giant TCRs) and I do miss the dual sided functions, but in terms of accuracy, I don't see/notice a difference.

My friend owns an S-Works SL8 that came with dual sided 4iiii Precision 3+ Pro PM and he says it's not accurate. He's gotten dual sided Garmin PM pedals instead.

My 4iiii left crank meter quit working a few months after it's warranty expired. 4iiii wasn't any help at all, not with repairs or a replacement discount.

I would stay well away from the Shimano double-sided crank power meter. It’s proven to be very inaccurate. Best to read DCRainmaker’s highly detailed reviews. I think the problem is on the drive side crank.

I had good, consistent results with a single-sided 4iiii (Specialized branded version) on a LH Shimano 105 crank. My current bike has a SRAM Quarq crank PM which is also very good.

I haven’t used PM pedals, but they seem a bit more fragile/inconsistent than crank based PMs. But they have the advantage of being able to easily swap between bikes. Again I would read DCR’s detailed reviews before buying anything.

Before I had a PM, I thought that pedal based PM's were the way to go. Why wouldn't I and everyone else want a PM that they can move from bike to bike. However I really don't want to change pedals from bike to bike just to give the bike I ride a PM. So I got a 4iiii crank arm PM. 4 years later, it still works and does all I need and most of what I want.

It might be a good idea to stay away from Stages power meters no matter how good of a deal you find. Their customer service will be non existent.

I thought Giant had pretty good customer service.

I have Garmin and Favaro power pedals and SRAM spindle power meters. The SRAM power meters are flawless. The Favaro is near flawless, but uses a proprietary charging cable (no idea how to replace it when I lose it). The Garmin power pedals are sketchy on reliability. No idea about relative accuracy. If you are using a pedal extender on the left pedal, power pedals won't work.

I have the Duo SHi on some SPD-SL 105s and they are great. Very accurate and don't add much weight. Since I run SRAM and the power meter is chainring based I much prefer these since I can swap them on any bike and not have to worry about buying a whole new PM once the chainrings are cooked. The only caveat is that they do had a bit of Q factor, thus if you aren't used to it or have hip issues I wouldn't recommend them. But I commonly switch from my bike with the Duo Shi with the bigger Q factor to my other bike with normal SPD-SL pedals and a left sided crank arm PM with no issue

A word of warning to all of you buying one sided power meters. There will come a day when one side of you definitely weakens vs. the other. What that means is that your readings are going to be either over or under what your real power is when that happen. I've had Assioma Duo pedals for a fairly long time now and my dominant leg, the right leg, has undergone two surgeries now for meniscus problems and I also currently have bursitis in that hip. My left leg has been fine. Over the years I've seen my L/R power output go from 48/52 to 55/45. If I only had a left sided meter, which most are, my power would have remained the same even though I know I can't put out as much power with my right leg. I'm far from crippled by it, I just can't quite put out the power anymore with it. My Assioma Duos have seen a decline in overall power as I'd expect. If it had been the other way, with my left leg having the issues, my power readings would have dropped by much more than expected, given my right leg would be fine.

I should note too that I didn't really notice it while riding, it was only when I saw the actual numbers that I realized what was happening. Except now with the bursitis it actually hurts so I do notice. I try to ignore it but the power meter tells me otherwise.

If you're young and injury free maybe it doesn't matter, but if you're getting older like me (70) it is something to consider.

Sounds like the epitome of anecdotal reasoning there zacster

So does this only apply to those with a single sided PM. Or is everyone that doesn't have a PM at all included in that dire warning?

And actually, didn't your issues happen to someone that had a dual sided PM?

TL;DR summary: for most people, single-sided is *probably* fine.

I usually try to stay out of these arguments, and my opinion and attitude about the single-sided vs. both-sided debate have changed over time. I've been using a power meter since the last millenium (this year marks a quarter century that I've been using power data). I did what I think was the first close analysis of a single-sided power meter (the late and not lamented at all Ergomo BB), and I also did what I think was the very first analysis of the Stages single-sided crank, for Ray Maker (DC Rainmaker). Importantly, one of the remits that Ray had set when he asked me to help him was that the single- vs. both-sided issue was off the table. Because of Ray's influence (and my analysis), although Stages had already announced a release date, they held their product back for another six weeks and revised firmware to address (not quite fix) some of the problems I'd identified. I consider that a good outcome: the public got a better device when it was finally released than they otherwise would have had.

But the reality is that Stages changed the market not by producing a superior product but by undercutting the price. They sold power meters that were roughly 60% the price of existing products, and sold people on the idea that accuracy didn't matter, only consistency does.

I thought then, and think now, that this is myopic. But over the years, it's become clear to me that I'm in a minority (as I am on so many things), and they won that war. Although there are many things you can do with power data, people have been convinced that these still-expensive devices are the best tool for training, and so they use it for training and nothing else. In fact, training (especially training FTP) is arguably the least demanding use of power data: that's why people trained successfully for about a century before the first power meters hit the market, and then trained with stop watches, speedometers, and heart rate monitors when each became affordable and available. There are things you can do with a power meter that you can't do with a stop watch, speedometer, or heart rate monitor, but the hard fact is that people don't do them. Recently, people have been eschewing on-bike power meters in favor of smart home trainers, which is pretty clear evidence of their uses and preferences.

So, I've had to change to mind about single-sided PMs. I think that as long as you only do training for FTP and you're not obviously physically impaired, single-sided is probably fine. You see people buying an additional power meter either for another bike, or as a replacement, or inside a smart home trainer, that gives different data -- but they think it's perfectly acceptable that they've been training for years with inaccurate data. That's because training is the least demanding use for power data. To me, that should trigger the thought that maybe they didn't really need a power meter at all, but that's just me.

Bottom line: if all you ever expect to do is train FTP, single-sided is probably fine; a heart rate monitor or a speedometer and a stopwatch is also probably fine. You may very well have challenges down the road when you buy a second (or third) power meter, but that's in the future and hardly anyone thinks that far. There are a handful of people who have obvious physical impairments (I have a friend whose left leg had to be amputated -- single-sided wouldn't work for him at all), and another handful who do things that require higher data fidelity, and a few who think ahead to a time when they need to replace or buy an additional power meter, but if you're not in those groups, single-sided is probably fine.

I own a Tarmac S-Works SL8 with SRAM red components and power meter. I chose the SRAM over Shimano for, IMO, better braking and the SRAM/Quarq power meter tech over 4iii. I have Garmin power pedals on other bikes - meh. Double side PM for me, single side for everyone else.

It's like when Infocrank came to the US and hit the market claiming their accuracy was incredible and then found out no one was actually willing to pay for it.

OP - you'll find there's tons of options all over the place that give data that is "good enough" to do absolutely everything you could possibly want to do with it. Personally I am more of a fan of crank based as it's just easier.

In all of our years of powermeter use and selling through just about every platform the only ones we have had "issue" with in terms of it's performance with respect to the level of training or use we were using are the Garmin pedal based systems, some of the old stages setups. Shimano's crank powermeter systems. SRAM (Quarq) have been great since day one nearly but even now just kind of are pricing themselves out of the business (but the fans will still buy it for at least a while). 4iiii is currently my favorite as I am pretty much completely back over to Shimano drivetrains for personal use. I have bought 3 in the last year and used them in all conditions of training and racing gravel/cross and they have performed nearly flawlessly (one stopped running on my 50th birthday ride a week or two ago but the temp was near the single digits. haven't had a problem with it since).

pedal systems make sense to newer users for some reason but in reality you will find you don't like swapping it. It's like what we used to do with hub based units. You could move them to any bike and yet I built an entire wheel business on the fact that everyone actually wanted one for each bike so they didn't have to move them. *shrug*

Also swapping a left side crank arm is easier than even swapping pedals most of the time if both bikes use the same pedal platform.

Just have to quote this for posterity. Only the second time in 30 years I have heard someone actually say this.

Maybe I'm just lucky, but every Garmin bicycle product (at least 10) I've owned has been junk from a reliability perspective.

Woah. I think in your situation I might've stopped at maybe around five or six of them. Eight, tops.

Well, I had 4 power pedals before the first one failed @ 7 months and second @ 8 months (the two on the tandem are still alive, but we don't ride it as much as the singles) and two Varias (at least Garmin has a replacement program to deal with their charging port design flaw). I gave up on their cycling computers years ago.

I've used a pair of PowerTap pedals since 2018. The P1 failed under warranty and SRAM replaced them with the P2, which have been flawless since. I don't mind swapping them between bikes, including ones that I've since sold (obviously keeping the pedals, which is easier to do and more useful than keeping a crank-arm installed one that comes with a bike and might not work with any other bikes you'll end up owning). I've taken them on vacation and used them on a rental. I've used them to verify the accuracy of my smart trainer and smart bike power readings. And once I start riding outside again after recovering from a broken leg, I'll use them to track my L/R balance.

And I stand by it and I have another racer / coach who purchased 2024 SRAM and agrees. So we are both thankful but not humbled by your posterity quote. And yes I test rode the Shimano dura ace brakes and own another bike with Dura Ace disc brakes and the SRAM are slightly better.

I have several sets of Favero Duos and a set of Favero Pro MX pedals. I've done the SPD hack on the duos so I can use SPD cleats and MTB shoes. This was before the Pro MX SPD versions were released. They all work well. Zero issues.

The Faveros are also one of the least expensive options available. And are considered as accurate as any power meters available. I simply have no reason to consider another option.

Concerning single or dual sided. I happen to have all dual sided. But I don't think it really matters, at least for training purposes. As far as I know, all power based training plans are proportional to some sort of power test, Usually a 20-minute FTP or ramp test test. As long as the same PM are used for the test as for the training, absolute accuracy doesn't matter. You could take all the values and multiply by an arbitrary scaling factor and the training plan would work exactly the same.

What I've noticed with my dual sided meters is I have a significant difference from left to right. Typically something like 55%/45%. But it's always about the same. So, if I had a single sided PM, it wouldn't matter for training purposes.

Now, if you're going to use your PM data or FTP value in pissing contests with other people, then I guess absolute accuracy matters. Or perhaps play around with data to estimate things like rolling resistance or aero drag, accuracy matters. And of course it matters if your competing on something like Zwift.

I like data, I do play around with engineering data like rolling resistance and aero drag, so it matters to me. But really for curiosity sake more than anything. And the cost difference doesn't matter to me.