First time power meter

I am looking to get my first power meter and one of these is what im looking into. The 4iii and or ASSIOMA.
I realize one is chainring and crank and the other pedals
Im just wondering what anyone has to say about these
Thanks for any help!

It’s been widely discussed on this forum, but if you’re using Shimano cranks, the 4iiii (or any other brand) will report some screwy stuff, usually reading low on the right side I believe, due to Shimano’s asymmetric crank design on the newer stuff (I think the 5800/6800 series cranks don’t have this problem).

I use a Quarq (spider based) meter, so I can’t offer any firsthand thoughts on the Assiomas, but the portability of pedal based power meters is nice.

I would go pedal based personally if you have multiple bikes. I’ve got Vector3, had some issues but rock solid the last year. Everyone I know with Assiomas is happy.


Only issue with the assiomas, unless this has been rectified, is that for the duel sided pedal power meters they connect via two different bluetooth sources meaning that each pedal is independent of the other. This is only really an issue if trying to get the left right data to read on a head unit. I would recommend for the same cost is getting just a left sided crank arm power meter as they are relatively actuate, tend to be a tad cheaper, and the benefit of duel sided power isn’t all that great unless you have a glaring imbalance.

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The Assioma are getting good reviews if you want a pedal based system.
I would encourage a dual-sided power measurement over a single-sided. It is not that single-sided are inherently bad, but should you change to a dual-sided (or trainer power) at a later date your power PRs may be skewed. I know people say that it doesn’t matter if you don’t have a large imbalance, but the problem for most people is that the imbalance is not the same at all levels of effort and can shift during a ride. As an example, in a recent workout, my balance changed about 3% between different intervals, but was also different in rest periods.

I have had several power meters (Garmin Vector V2, Stages, Quarq) and am happiest with the Quarq. The Vectors work well for me, but I wouldn’t buy the V3.

yep - have 2 Assioma single side meters 1 on TT 1 on summer road bike - both faultless - consistent (can’t vouch for accuracy - as I haven’t compared it with other things), connect to my Garmin 520+ in seconds, battery charge lasts ages and no faults or issues. Excellent

Single sided 4iiii is very reliable and offers great value.

This is not the case. They simply transmit data from both pedals through the left pedal. I am getting L/R data on my wahoo roam no problems

Also a 2% imbalance (not out of the norm) translates to a 4% variance in power readings, which is not exactly insignificant

I just got the 4iiii dual sided precision pro on my mtb, sram xx1 crankset. They were super easy to work with and turn around time was 2 weeks. Accuracy is spot on. Just my experience

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I’ve the older Favero Be ProS on my TT bike which I use on the trainer and a 4iiii on my road bike and like both units they’ve both been reliable and give me results which are consistent to each. I think the Assimoas have more flexibility so they’d be my choice.

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Having only used crank based power meters I couldn’t be happier with their results and consistency. Instead of 4iiii I would recommend looking at Quarq and Power2Max. Both have been flawless for me.

If you can afford the Assiomas then I highly recommend them. Easy to install and move between bikes if needed, rock solid, super accurate.

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I at first did but with using shamano cranks, I wasn’t 100% what to get so gave up honestly plus when I saw the 4iii i guess i lot interest
but id be curious to hear if you run shaiamo what you got

Yes, currently using Shimano and on that bike I am using Power2Max NGeco Rotor ALDHU 24mm. This is the direct Shimano replacement option. All you have to do is swap over your Shimano rings. It’s been a very good option. I would consider this power meter for all future Shimano bikes.

I also have had three different bikes with Quarq DZero or AXS power meters over the last few years. Again these have been very good. Quarq also makes a power meter specifically for Shimano chainrings - Quarq DFour. As with the P2M option above, it comes with crank arms

With the Quarq you are kind of locked into their new DUB bb standard or GXP. Either way I still think Quarq or P2M are good crank based options. Good value, excellent accuracy, consistent. Only negative is you have to give up Shimano crank arms. For a while that was an OCD issue for me, but i’ve since got over it.

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Think that’s a bonus, give that they seem to break rather easily.

I think that’s a bit of an overstatement. If you think about how many Shimano cranks are out there in existence compared to how many overhyped #metoo internet posts you are claiming widespread failure, it’s probably a fraction of a fraction of a percentage. I personally don’t know of anyone who’s broken them, it happens, but definitely not “easily”

Edit: nice article here- Understanding a Shimano Ultegra crank failure | Exclusive - BikeRadar

They shouldn’t break they way they do. That is more significant than the actual number. Not sure why you need to defend it so robustly?

I have seen a reasonable number of failures of the R8000 without looking for them, including one of mine that I was hoping to sell on. I have never crashed, have rather low power compared to most, and rarely do full on efforts. I would strongly advise anybody to seek an alternative where possible. At the minimum they would have a crank that might fail after a few years, but at the worst the failure could result in a serious crash.

You say defending robustly, I say analyzing objectively. I’m sure you can find evidence of every single type of crank having a failure, safest bet is just to stay off the bike or buy billet

You are probably right, so all the best. I hope your cranks have a long and healthy life.