Barry2 

202
198
199

accurate within 1%
id bet my home scale can’t achieve 1%

Seattle Forrest

Well played. 🙂

My average power is a number. Definitely not an animal or a vegetable.

Doomrider74

Ive been reading some reviews on the 4iiii pm and the feedback is the data is somewhat spikey which, for some, has made it difficult to use. That's even with power smoothing on.

I'm now wondering if I could accommodate the Assioma Duos, although I have some concerns with those:

1. Non replaceable, rechargeable battery: presumably, once these die, the pedals go in the bin? A bit expensive if outside of the 2 year warranty.
2. Id need to get a second pair of shoes as I have Shimano pedals on my other bike,so that would have to be factored in (or replace the pedals on that as well)
3. Ive never used Look pedals before: how do they compare to Shimano?

I know the Garmins are Shimano compatible but they are very expensive. They also haven't been out long, which is a concern given the longevity issues the Vectors had.

ericcox

They claim the rechargeable battery should last for several years (I believe they claim 500 charge cycles at a minimum). I've only had mine since last September. I ride a fair amount - I average 1000-1200km a month; I typically charge every 3-4 weeks, usually before it is really needed. That said, yeah, they're toast when the battery wears out.

Depending on how nice of pedals you want on the other bike, it would probably be far cheaper to buy a set of pedals rather than shoes. I think the relatively cheap Keo Classics are the way to go if the other bike isn't for racing / high performance. I road Keo classics for years on a few different bikes and was always happy with them. My son's first clipless pedals were a pair of my old Keos - it didn't take him any time at all to be comfortable with them.

In terms of difference with Shimano, I can't say much given that I haven't used SPD-SLs. What I've heard from people is that the platform is a little bigger on the Shimanos, and some say they are easier to clip into. I can say that Assiomas are harder to clip in to than standard Keos. They spin really freely, so until you get the hang of it, it is very easy to spin the pedal and have trouble clipping in. That said, this has caused some annoyance, but has never been a problem on the move.

I do find them easy to move back and forth between bikes. I've used them on my gravel bike for a race with absolutely no technical elements - just gravel roads mixed with pavement - and have used them on my Peloton Bike +. It really is as easy as changing pedals. So... count me as a fan.

PeteHski

Power data is inherently spikey, which is why most people use a 3 or 5 sec averaging filter on their head unit. Nothing is very spikey when averaged over 5 seconds.

PeteHski

This is what I've been using for the last 12 months:-

https://www.specializedconceptstore....5-upgrade-kit/

Batteries last around 6 months and are just an ordinary button type.
I wondered whether I might want to "upgrade" to dual sided, but never felt the need. Having compared power data with my indoor Elite trainer (which has a built-in optical power meter) they agree within literally a couple of Watts average over anything up to 5+ hour sessions. I have been amazed how consistent these 2 independent power measurements have been in relation to each other.

Doomrider74

As I said, it was with power smoothing on. It was also compared to other PMs, such as the assioma uno, which weren't as spikey.

Seattle Forrest

How do you train / ride now? Unusually spikey data would be a problem for me for very short ( less than a minute ) intervals but I don't do much of that. If the data is accurate but spikey that wouldn't hurt my sweet spots. Or my JRA. 🙂

All power data is spikey, almost everyone shows a rolling average. Based on the folks I know, the big number on your head unit is either 3 or 30 seconds.

@RChung is right about not always knowing what you're going to want to do. Sometimes people don't fully realize what's possible until they start using something.

Doomrider74

I can't seem to get those here in Canada. I wonder if it's because 4iiii, who make them, are Canadian.

PeteHski

That doesn't make a whole lot of sense, since you can smooth the raw data as much or as little as you like. Like most people, I run a 5 sec rolling average for general road riding and that works fine for taking out the "lumpy" nature of pedal power. Out on the road I only look at live power when riding in a steady state, such as pacing myself up a long climb or in TT mode on the flat. I've never had a problem with spikey data in those real world scenarios. When analysing data off the bike, my crank power data does look a fair bit more spikey than my turbo power data. But once you apply a software filter it looks the same. It doesn't affect any power averaging over time either.

PeteHski

That's a shame. I know Specialized added better weather sealing on the unit (which does make it more bulky too) and did some of their own tweaking with the calibration and temperature compensation. But I would imagine the 4iiii version is very similar. Reviews I read of the 4iiii seem to align with my experience of the Specialized version. The only reason I bought the Specialized 105 crank meter was because it happened to be on sale at the time and was actually cheaper than the standard 4iiii. Reviews I read of the Stages PM seemed a fair bit more hit or miss, which is why I tended to favour the 4iiii sensor. Reviews I read of pedal based systems also seemed a bit iffy. People complaining of poor consistency, failures etc. The crank based meters appear to be more robust and consistent in general, which kind of makes sense as a crank arm is just about perfect for adding a strain gauge bridge. It's a little bit more complicated and vulnerable on a pedal, although they seem to be improving.

Doomrider74

Thats one of my biggest concerns with a pedal-based system: its quite a vulnerable area to have such an expensive bit of kit.

Doomrider74

It was the Shane Miller review of the 4iiii, if you want to watch it yourself. The reason I mentioned it was to see if anyone had found it to be a real world problem: if the answer is "no", then that's a valid answer. I'm not coming at this with any bias, except that the 4iiii is at a good price point.

PeteHski

That was exactly my thought as a mech eng. Reviews seem to reflect it too. Lots of reviews to the effect of "they were great at first and then stopped working/dropped out/gave dodgy data etc etc". Fairly predictable really. Crank based sensors should be reliable and consistent as there is really nothing much to go wrong and they are unlikely to get kicked or clipped.

PeteHski

I'll check it out when I get a minute. His reviews are normally pretty good. Be interesting to see what limitation he found. It's certainly true that the raw data is relatively spikey, but I think that's simply because pedalling really does create a spikey power output. Like most raw sensor data it just needs appropriate filtering, both for real time use and off bike data analysis.

Doomrider74

I get that, but it was the comparison with other single-sided products, with the same power smoothing applied, that drew my attention.

PeteHski

Just watched Miller's review and I see what he means about those little spikey drops on the 4iiii. Looking at my own raw data on the Specialized version I don't see those kind of specific spikes, so maybe it's something in the 4iiii firmware causing that. But in any case those little spikes would not affect any real world use or data analysis. By that I mean they would not show up on your head unit while riding or significantly affect any post ride data analysis. Definitely not a reason to dismiss this very cost effective power meter.

Doomrider74

Any issues with using the 4iiii with out front mounted head units? I believe until Gen 3, the Stages ones were hit and miss with head units mounted to out front handlebar mounts, due to the signal power, or lack there of.

guachi

I never had problems with my 4iiiis connecting to my Wahoo Elemnt Bolt

JohnJ80

I have three stages single sided gen3 power meters. They work flawlessly and they're largely set and forget. Their customer service is amazing and a big differentiator, I feel.

I am not a fan of pedal based power meters because you're locked into a pedal/cleat standard. This is a problem for me when I switch bikes from road (speedily or look based) to gravel (spd mtb) and especially when I transition over to winter riding and I'm wearing mtb shoes when riding on the road.

Doomrider74

Well, I've gone and done it now: I've ordered the 4iiii one. Tips welcome

rm -rf

I'll recommend Stages single sided over 4iiii single sided. See below for the poor 4iiii support when it broke.

The stages doesn't have annoying 1-second extreme power numbers. Every few rides, I had to edit out a couple of 1200+ watt recorded numbers, where the data on either side was quite close to zero. This throws off the Golden Cheetah charts, so I'd search these extremes and set the values back to low numbers. Without the edits, the Golden Cheetah Critical Power Chart's curve got distorted at the under 1-minute range by these 1-2 second incorrectly high wattages. I think Strava filters out these short spikes automatically.

The Garmin popped up a "Stages low battery warning" when I was riding last week, so I swapped it when I got home. Yes, the CR2032 was quite low voltage, but probably could go for a few more rides at least. This notice is very helpful, and the 4iiiii didn't do this.

I think the Stages maybe reports higher watts on similar hard efforts. Perhaps it's just less variable, and might be more accurate. ..

The stages has a better zero offset, with an actual result number to see if it's staying in the same range. The stages asks before each ride start on my Garmin if I want a zero offset (but perhaps that's a new Garmin firmware change?) The 4iiii had to go into the settings menu to zero it, and it only reported "10" = successful.

I haven't seen any dropouts from the Stage's data transmission to my out-front Garmin. The old communication problems seem to have been solved a few years ago, I think.

I did like the 4iiii at the time. A single sided meter is fine for my uses: mostly pacing and watching seasonal trends. I didn't do any formal power based training.

4iiii failure
I was very disappointed with 4iiii's support. The meter worked fine (other than the 1-second glitches) for 3 years and 3 months. It has a 3-year warranty. Suddenly, on a ride, I got readings of 500+ watts when soft pedaling, that should have shown less than 100 watts. Then it quit altogether a few days later, and no troubleshooting helped.

4iiiii said to contact my store Clever Training for warranty support. (This was last year, during covid.) Clever Training said to contact 4iiii. Both of them kicked the problem down the line for more than a month. Finally, a 4iiiii supervisor explained that there was nothing they could do for me. I was expecting at least a discount on a replacement, since it had failed so soon.

I put off replacing it for a while. 5 months later, I bought a new Stages arm. It's so nice to have the power numbers while riding.

EDIT---oops, I posted this just minutes too late for the OP's 4iiii order! Perhaps you can return it.

RChung

Here's my standard advice to new users of power meters.

Doomrider74

Cool. Thanks for that

rm -rf

I often use 3-second and 30-second views together, which is very helpful for pacing. "30 second is dropping, add more power....oh, that's too much, ease back a bit." I also have a separate Garmin screen page for climbing, with 1, 3, 10, 30 second watts, along with HR, grade, etc. That's useful to me.
My Garmin map screen for navigation shows cadence and 3-second watts at the bottom. (A 5-second average would be nice. Garmin doesn't do that.)

As I mentioned in the previous post, the short 1-2 second 4iiii power spikes were annoying for after the ride statistics. The Stages doesn't have them.

The second-to-second power variability was quite surprising to me when I started using a power meter. It's extremely hard for me to keep the watts steady within 10 watts or so. Normal riding can vary 20% or more as I'm just riding along.

~~~~
It's interesting how complicated it is to convert a bending crank arm's strain gauge data into real world watts. For instance, just standing on a pedal will bend the arm, but it's not moving, so it's ignored. The articles on the Ultegra right side arm problems mention how the arm can bend in both length and in a twisting torque, and it interacts with the chainring spider. Very complex.