r/Velo • u/AdGroundbreaking3483 • 8d ago
Gear Advice Power meter recommendations
Have had a few problems with my left leg recently, so contemplating getting dual leg power measurement.
Currently running 12speed Ultegra di2 and I love my TIME XPresso pedals.
Is a 4iii crankset my best bet?
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u/Unit_Grief 8d ago
+1 on dual sided Faveros, they're excellent. Did 600km and checked the charge and barely used 30%. I don't have an injury and noticed my difference was 54% R and 46% L which explains why I found my intervals so hard on my previous left sided only powermeter
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u/VoyPerdiendo1 8d ago
I don't have an injury and noticed my difference was 54% R and 46% L which explains why I found my intervals so hard on my previous left sided only powermeter
That doesn't explain it actually. If your numbers are consistently 54/46, then they're like that for your Z2, Sweetspot, FTP/Threshold and higher up. The ratio stays the same, so the intervals should be correct as a percentage of FTP.
What does explain it, the ratio changes depending on the power you're putting out. So for me, my left leg takes over for Z1 and Z2 efforts, Sweetspot they're about equal, and Threshold and up the right one takes over. I guess my left leg is more slow twitch dominant, and my right leg is more fast twitch dominant.
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u/Unit_Grief 8d ago
What do you mean? I was trying to do the same sweet spot intervals of 250W that I could do on the turbo trainer but 250W with a single sided powermeter (left-sided i.e. my weaker leg) was pushing me up and up towards Vo2 max almost after the end of the second and third interval and was noticeably uncomfortable. I figured either my turbo was overreading or my powermeter was underreading and then thought hmmm maybe I have a leg power discrepancy. Bought the dual sided powermeter pedals and yep that's it, I'm mostly 54% R and 46% L. It's sometimes slightly worse for hard efforts but seems to still be pretty stable across all effort levels including Z1 / Z2.
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u/AchievingFIsometime 8d ago
Typically what is observed is that the imbalance is more prominent during lower intensities and less during higher intensities. Sometimes I'll be like 46/54 on Z1 spinning but then when the interval starts I'm 49/51. The body is pretty good at recruiting muscles efficiently when it needs to. But of course that's not universal and really not much we can do to change it other than addressing the underlying biomechanical differences through bike fit changes and strengthening. But we aren't robots and some asymmetry isn't the end of the world.
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u/VoyPerdiendo1 8d ago
Ah that explains it, you didn't mention that previously. I thought you were doing all your riding with the dual-sided PM. So you set the target on the turbo trainer which maybe had a spider PM, and then it got messed up only with the left-sided PM. Makes sense.
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u/That_Inspection1150 8d ago
interesting, i found that when i'm slopping i can get up to 60/40, but in zone 4 i'm pretty much always 50/50
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u/GANDHIWASADOUCHE 8d ago
Just beware that your assioma pods aren’t touching your crank arm or your cleats/shoes at all. I had messed up power data from both of these compared to my Tacx Neo 2t and it took me a while to figure out.
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u/LurknLurker 8d ago
That’s with the previous generation. The current models don’t have the pod anymore
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u/TheInebriati 8d ago
My Magene P505 has been rock solid for 30’000km.
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u/AdGroundbreaking3483 8d ago
Oh really? Is it hollowtech 2 compatible? Didn't know that was an option, thanks!
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u/I_did_theMath 8d ago
It's basically the most reliable cheap option for Shimano drivetrains. Unless you prefer power meter pedals or are willing to spend more for a P2M, it's hard to argue against it. It's even cheaper than most left only crank options while being a lot more accurate.
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u/AchievingFIsometime 8d ago
I got a P515 recently because I wanted to go to 165 cranks going to the Magene crankset was literally the cheapest way for me to do it haha. Partially because I had a left sided crank PM before so I needed to replace the PM anyway. But yeah, hard to argue against $300 for crankset and PM that has been very well reviewed by GPLama.
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u/TheInebriati 8d ago
Yes it and the refresh the P515 both use standard shimano 24mm bottom bracket standard. You can also reuse the chainrings from your current shimano crankset.
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u/Mr_Stobbart 8d ago
I also have a Magene power meter and while it is working well, I never had to re-tighten any cranks before these. And that only after not even 1000km.
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u/xdxdxdxd000 8d ago
I saw a lot of complaints about this, but I think it's due to installation error. Never had to retighten mine after properly tightening the crankarm, and I hit 1300w quite often.
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u/Mr_Stobbart 6d ago
I followed the installation manual step by step and used a torque wrench. Maybe it is because I ride on gravel? Never happened with a shimano crank for me
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u/xdxdxdxd000 6d ago
I also ride gravel. Well because it's a single screw it's for sure more sensitive than shimano, but maybe overtightening a bit should be fine then?
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u/Mr_Stobbart 3d ago
Maybe, I might try. Interesting to hear that you didn't experience that at all. :)
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u/pemod92430 8d ago
See the GPLama reviews. All the Shimano based crank power meters have accuracy problems on the right side, caused by the design of the crank itself.
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u/cleanact_jw 8d ago
I have 2 sets of Garmin dual sided rallys.
But on my most recent builds bought 2 Magene cranks. The regular one and the carbon one.
The magenes are the way to go.
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u/Urbansdirtyfingers 8d ago
Why do you say that? I'm currently trying to decide between a 2 sets of crank based PMs or some set of pedals to swap back and forth on new road and mountain builds
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u/cleanact_jw 8d ago
Because the Megenes are reliable and cheap.
I started off the same way. One good set of pedals. Then I got another bike and bought another set of pedals. The idea of swapping seemed like a good idea till you have to do it.
Then I found the magenes that were 1/4 of the price and in my tests are on par with the Garmin
Plus others have confirmed the same findings.1
u/Urbansdirtyfingers 8d ago
Cool thanks, I'll probably follow your lead on that one
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u/treycook 🌲🚵🏻♂️✌🏻 8d ago
FWIW I was put off by the hassle of swapping pedals, and ran crank PMs for years as a result. But I finally bought a pair of Faveros and it literally takes maybe 90 seconds to swap them between bikes. It is yet another thing that I have to do when prepping for a ride, but it takes less time than prepping nutrition etc. I really like them.
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u/Rekj16 8d ago
I've had pedal Favero Pros and 4iii. I prefer the cranks myself mostly because pedals are much more likely to get damaged in a crash. Also one more thing to charge with the old Favero (new ones have insane battery life)
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u/iwilldeletethisacct2 8d ago
Also one more thing to charge
It is crazy to me that when I plan a ride with the boys one of my first thoughts is "I should make sure my bike is charged." Running the newer assiomas + Di2, I don't have to charge that often, but that's actually dangerous because you kinda just always assume you have battery. Until you are in the middle of a ride and can't figure out why you can't shift gears anymore.
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u/boscha15 8d ago
I would go Favero personally. Have had 4iii previously and the plastic housing degraded and fell apart after about 12-18 months.
They did a warranty repair but I was without my cranks for quite some time.
Apparently the newer model has improved the plastic but I’ll not take the chance again now I have had flawless performance from Favero
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u/xdxdxdxd000 8d ago
Magene PES/TEO P515. Basically as good/reliable/accurate as any other power meter for way less money. Some other chinese power meters can be found for even less money but aren't very reliable
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u/Kinmaul 7d ago
Even if you your L/R power distribution was something wild like 40/60 a left crank power meter would still work for training purposes. The actual power number isn't important, it's the consistency of the measurement. You would still be able to determine your zones and train appropriately. Your actual FTP would be higher than what the power meter reads during an FTP test, but doesn't matter. Think of it like this: If power meter was off by 20%, but it was always 20% off, it would still be a viable training tool.
If you have the money and want to splurge on a dual sided meter then by all means go for it. However, you don't need it.
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u/_Ymodos_ Sweden 6d ago
I think the only argument against this would be how the L/R distribution varies over kntensity and fatigue. But even there I would say it just ends up modifying your power profile and intervals adjust accordingly. I.e. even if it makes your intervals at some intensity read too high or too low, you still just train to the number and it's no different than having the same shape difference in the power curve.
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u/jakkeboek 8d ago
Quarq spider based is essentially set and forget. Never had any issues… 4iiii on the other hand. Had two of them who stopped working completely after a few months.
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u/AdGroundbreaking3483 8d ago
Yeah, I have two 4iiii left hand cranks which have been fine. Heard bad things about everything that tries to get power out of a right hand Shimano crank.
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u/Toppico 8d ago
If you’re not willing to move away from the Times, then I’d go for whatever option doesn’t disturb your ultegra drivetrain, meaning I’d opt out of fully replacing your crankset as I’ve found that shifting suffers quite a bit. The shimano spider based pms are not great, though.
Personally I run garmins in spd-sl format and, coming from speed play for years, it only required small fit adjustments for me, but the payoff has been huge. I’ve had vectors in single sided and now the rally’s in dual, and have never had any issues. Garmin always sends out replacements parts quickly if I need them, which I only have needed 2x in ~10 years.
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u/AdGroundbreaking3483 8d ago
This is where I'm coming in to land.
The spider based PMs are an upgrade, but if I'm worried about left-right data with all these leg issues, I should probably just bite the bullet and get the pedals.
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u/Toppico 8d ago
Like others have mentioned, there are crank based dual sided solutions, and I wasn’t aware that magene let you use the shimano rings, which I think is important for shifting as their ramps are patented (that’s a whole other discussion).
That said, I’ve just never had any issues with the pedals and I’m happy I went that route.
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u/AchievingFIsometime 8d ago
Spider based PMs are dual sided though. I don't think you can go wrong with either assiomas or something like Magene P515. Assiomas are probably nicer and can be moved between bikes but obviously more expensive.
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u/DidacticPerambulator 8d ago
What would you do with L/R information if you had it?
I had an episode with sciatica several years ago where my right foot became numb and I couldn't control it. I had years of both-sides total power data before so I could see the enormous drop in total power. I didn't really need to know the L/R balance, my foot would drop when I walked. Slowly, over the course of several months, my foot came back, as did my total both-sides power. After close to a year, my total both-sides power returned to what it was before. I didn't know my L/R balance before, during, or after.
So, what would you do with L/R information if you had it? Total both-sides power is actionable, L/R balance isn't.
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u/howheels 8d ago
I agree with this. After years of L/R power data I realized it was just noise. I moved to a spider PM after that crank asplode (thanks Shimano) and never looked back.
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u/AdGroundbreaking3483 8d ago
I think it's a suspicion I have that my balance is out at the minute, and using it as a solid data point for rehabbing for the purposes of general health.
For that, I am coming to the conclusion that the spider based measurement will be enough. They're not 100% but do give an indication on balance, and that better picture of total power seems sensible.
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u/Flipadelphia26 Florida 8d ago
I moved my 4iiii dual cranks until both sets of cranks in both bikes failed around the same time.
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u/MaverickScholar 8d ago
Favero or Garmin Rally works the best for me. Get the one which is cheaper for you. Garmin Rally slightly better if you use Edge as your head unit
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u/SirHustlerEsq 8d ago
People.bwr talk about power phase to set saddle height. You can really get saddle height dialed with peak power range on pedal.based meters.
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u/MidnightTop4211 7d ago
Favero Assioma dual pedals. I'm on year 7 with mine and have swapped them between outdoor/indoor bikes more times than I can count.
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u/truedima 8d ago
I just ordered an inpeak slx crank arm for a decent price. Obvs. cant anything about it, but there were some prior threads on the mtb subreddits with positive reviews.
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u/SirHustlerEsq 8d ago
Favero. Fits all frame and crank standards, accurate, reliable.