Your fears regarding chain drop and damaging the P2M are justified. That happened to me. I partly ripped of the lid for the battery compartment on my old P2M S-type. That said I had to drop the chain many times before it actually happened. If the chain drops you will need to stop pedalling immediately. As always P2M was very supportive in helping me. So if you happens to damage your P2M do not hesitate to contact P2M. Maybe they have a reasonable solution available.
I like your videos so much... Being a cycling hobbyist and passionate mechanical engineer your videos are a joy to watch! Please keep doing your stuff 😃
Good stuff, really enjoy the engineering perspective in these vids. On a sidenote, P2Max is my favorite powermeter. I see no downside having switched from SRM.
On my MTB's I've using Stages, Rotor and now an SRM unit, I've been pretty impressed with all three. The stages works a lot better than expected, but it's been frustrating having to guess whether clearance will be an issue. Happy to see PM's trickle into the mountain bike scene.
As you mentioned a chain drop will hit the components of the power meter. I had a chain drop and it destroyed my meter. P2M did send me a new one cause it was under the 2 year warranty period.
I absolutely loved my unit(s), but a very unfortunate chain drop (wayward stick) as I kicked into a sprint resulted in the face place being ripped off. Died instantly. Not repairable due to their design. Chain retention device was used for the second as a precaution. But it was really an unlucky event that caused the first
Put a Power2Max on my XTR crank on my MTB to track my stress (as I'm always chasing skinny guys straight up steep hills for the quickest route to good dirt. Works great! I cannot fit a crank arm based PM because of the clearance to the chain stays.
Looking forward to the data analysis vs Assiomas. I've hacked mine to use MTB SPD XPedo cleats but it's still not ideal due to risk of bumps, so I also plan to switch to Power2max on my mtb.
You sure you went from a 34T to a 36T chainring? That Wolf tooth in the video is a 34T, your XT was a 32T in that case I assume? Nice video btw. I agree a chainring PM is the best option for MTBs. I had a Power2Max NG Eco on my road bike for two years and loved it, absolutely faultless, it just worked every time with no hassles ever. Went with Assioma Duos for my new bike and after 18 months with them I am also very pleased and have had no issues. I compared the Assiomas to the P2M on the old bike and found them to be within a watt or two in all my test cases, so very pleased with the numbers. I put an Xcadey XPower-S on my MTB last summer and so far I am very happy with how that's performing also. For half the price of the P2M and a third of the price of a Quarq PM it's a pretty good bargin IMO
So, perhaps a chain guide should be installed, if not to keep you riding, just to protect your PM? Would not trust the bolts to do much deflecting, and perhaps that cover over the PM spider electronics should be tapered and provide no chance for the chain finding anything to grab on. Since we are talking engineering here 😜 Perhaps a combo bash-guard like those from oneup , mrp or e*13, as I am guessing the PM would also (not) love you casing on your ring...
You could be right about the parasitic force on the crankarm powermeters, however I think Stages have done enough testing to compensate for this. If you are right, pedal based powermeters must the worst.
Of course, Stages have more or less got it dialled now, with the exception of the SNR which is still quite low. The non symmetry is the main cause for the dodgy readings of most dual sided shimano crank PMs. I think 4iiii has a better gauge layout (which I think they patented) for crank arms.
What are your thoughts on pedal based meters for mountain biking? There are only a few choices(Garmin, SRM, modified Assioma SPD) but with how often pedal strikes happen in some terrain it seems like a very expensive system that will inevitable be destroyed/damaged.
Shame it isn't easy to source a powertap hub and compare accuracy with the spider. Surely a hub based solution is the ultimate in protection from damage from the surface.
I have three of the NGeco units and they have been flawless. Prefer the coin cell battery as I would be fearful of the plug in version suffering from battery drain after a few years.
Very good. + 256Hz sampling rate + forged cranks + decent full bridge gauge layout, easy to cancel parasitics & tune mV/V output of the circuit. + works with 24mm BB - Weight (if you care about that). - cost - minimal chainring options
Thanks for the great video. I have a burning question to ask you. My cycling GPS has a recording cycle of 1hz, When a power value is transmitted and recorded, is that value an average value for one second from many samples or an instantaneous value based on one sample? When I look at my power data the individual numbers are all over the place. This makes me think that my PM (Stages) has a sampling rate of 1hz. You mentioned that the Infocrank has a sampling rate of 256hz. What about P2M and Stages? Where do you find that info.? I have a P2M on order and I would like to know. 256hz is probably overkill but I think 1hz is way too low!
I am pretty sure the P2M samples torque at 50Hz. I am not sure about the angular velocity sample rate. But yes the Garmin will only output 1Hz and this is really the limiting factor. As far as I can see, the sampling and recording rates are not the only important distinctions either, as no crank/pedal based power meter actual calculates power based on a fixed time sample, rather power is calculated on a variable duration event basis, that being the time taken to complete a full revolution of the crank. The power meters and/or head units (which depends on the model of meter) then take this variable duration power data and “force” it into a fixed duration recording rate.
It's average value from many samples (1s rolling average). Why would you like to have higher sampling rate on head unit? You'd see your power fluctuating horribly during every pedal stroke... Power meters usually transmit at 4Hz but most head units record it with 1s intervals.
@@michwoz Thanks Michal. What is weird is that when looking at the 1hz rolling average samples my power is all over the place. This is an observation made on both Quarq and left only Stages. The Stages fluctuates more than the Quarq due to the left side only. But even with the Quarq it fluctuates a lot. On my Garmin head unit I have 3s. avg. and 30s. avg., and I mostly look at the 30s. avg. value. The 3s. avg. fluctuates a lot and it's mostly useless other than for a sprint. I wonder if our power output really varies this much due to a lack of a flywheel effect when we pedal.
@@jonathanwoo6597 Could you please describe what "all over the place" means for you? Power does in fact varies between pedal strokes. For some people more, for other less. I've seen a lot of different people power graphs and it may fluctuate A LOT. It's more about pedaling technique than power meter sampling or any hardware issues. Humans are not robots. At least most of them. There are people who can maintain very steady and stable power graphs, but they are minority.
Great video. Benchmarking: I'm not so sure if readings from Favero Assioma pedals should be trusted so much that the readings can be taken as a ground truth. I own eight power meters, and they are all very consistent, which is very good. The power meters that read a little lower than the others always do so. But which power meters give the best readings? We always want the truth. Currently I have three power2max units (two Type S, one Classic). Very consistent readings - the readings are about 1.5 percent different, but always in the same pattern. Of course two spider power meters can't be compared simultaneously, but I found this by comparing to a Direto X trainer, which is also very consistent at a given offset value. To the Favero Assioma DUOs. They read 2-4 percent higher than the p2ms, and also 2-4 percent more than two SRMs and a Powertap hub. It reads approx. the same as the Direto X. I think Assiomas are very sensitive to angular calibration. To get a good alignment during calibration, I hang a coin from the pedal axle and align the crank arm so it is angled straight upwards. This makes repeated calibration after several rides necesssary as the pedal axles get more and more tightened to the crank arms. By comparing power meters on the Zwiftpower tool, the Favero Assiomas have some spiky fluctuations in the readings. Not so bad for averaged readings, but it seems like something is off. n=1 for my experience with Assiomas, but p2m might just as well give accurate readings. I trust my p2ms more. The Assioma pedals need to know the angle of the crank arm to decompose the force vector. The reliance on accelerometers might introduce an extra source of error. For oval chainrings, this technology is probably very well suited, though. I might be wrong, it would be interesting to hear your opinion - maybe in a future video?
Too bad shimano does not have the same crank design on their roads as on MTB. The non spline shimano connection seems to be better than the splined rotor cranks that I have on my road bike (however no issues to report so far luckily).
Why does nobody think about people that want to run a 30T or 28T chainring? There are no dual sided solutions in that case. Also, regarding better being off at anything lower than 34T, even a 30-50 combo is still faster than walking, And easier, as you're not pushing something along with you, the posture is much better, etc. I find it REALLY funny that people actually prefer walking to riding steep climbs. I'm out there to ride bikes, not to walk. And around here the climbs are steep. So steep I've often thought it's be nice to have a 28-50 combo instead of the 30T. I do prefer to have a slightly higher cadence than some people, but still, I can manage 1000 VAM on gravel on a 16kg bike with 2,5WT tyres at 1,5 bar. I really need a power meter to see what I'm putting out :D
Totally agree, MTB gearing is done wrong imo. I'd rather not walk extremely steep stuff (and I'm quite a climber ~5wkg). The standard 32t is like road bikes being fitted with 53/39's....which aren't popular anymore
There’s no way I’d replace that bombproof Shimano spider with that flimsy item. I’ve seen numerous third party spiders fail catastrophically and that doesn’t look safe.
@@PeakTorque For completeness: There are also SRM x-power SPD pedals. Have used mine for a couple of races - so far no problems but let's see in one year.
@@saynotothegreatreset I had a battery door vibrate loose on my vector 3 pedals during a road race and lost the battery; it felt like driving a car with no fuel gauge at that point.
@@PeakTorque I use Garmin Vector 3 on my road bike, but hesitate to use pedal based on my MTB. Looking forward to your conclusing on the Power2max. GPLama has a review og the Sigeyi. I guess you've seen that?
You are more likely to bash pedals on rocks etc when mountain biking. You may not want to risk damaging power meter pedals as they are more expensive to replace than regular pedals.
Hang on there. Aren't all movements and forces due to power applied to the crank arm? I know it's not what we want to measure, but one could argue that we could measure the actual power output of your legs, rather than the power applied to the drive train!..... Ok, I know it's kind of stupid... But hey... Thi K about it 😂
I understand that you dislike the gxp system and have made videos about why, can you make an update on how you feel about the new dub system has Sram redeemed them selves in your eyes
True, but since I have powermeter on my roadbike.. I wanted powernumbers on my mtb. I went with the favero assomia duo spd hack for my Mtb..works fantastic.. they can handle a lot of abuse as well
Why? Power meter is more useful in training and tracking your numbers (TSS, calories) than actually racing. You can race without PM, many don't even look at watts during races. But not having PM on MTB bike makes your total data incomplete. And many people care about that.
quite the opposite - in general I race mostly gravel and some road races (with poor results, but that's to be expected) and I use my MTB to have some variation in training. A PM is very useful for training - you can watch the power and make sure you don't over exert yourself on the off/recovery days.
Great analysis on this P2M and your configuration of it PT! Keen to see how your baselining goes against other meters.
Your fears regarding chain drop and damaging the P2M are justified. That happened to me. I partly ripped of the lid for the battery compartment on my old P2M S-type. That said I had to drop the chain many times before it actually happened. If the chain drops you will need to stop pedalling immediately.
As always P2M was very supportive in helping me. So if you happens to damage your P2M do not hesitate to contact P2M. Maybe they have a reasonable solution available.
I like your videos so much... Being a cycling hobbyist and passionate mechanical engineer your videos are a joy to watch! Please keep doing your stuff 😃
Thanks Viswan
Great review of different mechanics concepts and their application in power meters, A+
Good stuff, really enjoy the engineering perspective in these vids. On a sidenote, P2Max is my favorite powermeter. I see no downside having switched from SRM.
On my MTB's I've using Stages, Rotor and now an SRM unit, I've been pretty impressed with all three. The stages works a lot better than expected, but it's been frustrating having to guess whether clearance will be an issue. Happy to see PM's trickle into the mountain bike scene.
As you mentioned a chain drop will hit the components of the power meter. I had a chain drop and it destroyed my meter. P2M did send me a new one cause it was under the 2 year warranty period.
P2Ms are the greatest Power Meters in my eyes, they are just the workhorses of the PMs. :) Have one on my roady for 3 years and loving it.
I absolutely loved my unit(s), but a very unfortunate chain drop (wayward stick) as I kicked into a sprint resulted in the face place being ripped off. Died instantly. Not repairable due to their design.
Chain retention device was used for the second as a precaution. But it was really an unlucky event that caused the first
Superb review PT. Thanks
Thanks 👍
really great video
Put a Power2Max on my XTR crank on my MTB to track my stress (as I'm always chasing skinny guys straight up steep hills for the quickest route to good dirt. Works great! I cannot fit a crank arm based PM because of the clearance to the chain stays.
Great analysis as always, would you ever consider creating some more sailing based content particularly based around the high performance sector?
Looking forward to the data analysis vs Assiomas. I've hacked mine to use MTB SPD XPedo cleats but it's still not ideal due to risk of bumps, so I also plan to switch to Power2max on my mtb.
The backwards chainring bolts have caused me some extreme discomfort
Very interesting.
Rotor will do you a nice spindle based power meter that is modular and really accurate too.
have they fixed the power accuracy? (i.e. the only thing that matters when buying a PM): ruclips.net/video/2dV-XY0UT6U/видео.html
You sure you went from a 34T to a 36T chainring? That Wolf tooth in the video is a 34T, your XT was a 32T in that case I assume?
Nice video btw. I agree a chainring PM is the best option for MTBs. I had a Power2Max NG Eco on my road bike for two years and loved it, absolutely faultless, it just worked every time with no hassles ever. Went with Assioma Duos for my new bike and after 18 months with them I am also very pleased and have had no issues. I compared the Assiomas to the P2M on the old bike and found them to be within a watt or two in all my test cases, so very pleased with the numbers. I put an Xcadey XPower-S on my MTB last summer and so far I am very happy with how that's performing also. For half the price of the P2M and a third of the price of a Quarq PM it's a pretty good bargin IMO
Yep, good spot. 34t in, 32t out.
So, perhaps a chain guide should be installed, if not to keep you riding, just to protect your PM? Would not trust the bolts to do much deflecting, and perhaps that cover over the PM spider electronics should be tapered and provide no chance for the chain finding anything to grab on. Since we are talking engineering here 😜
Perhaps a combo bash-guard like those from oneup , mrp or e*13, as I am guessing the PM would also (not) love you casing on your ring...
You could be right about the parasitic force on the crankarm powermeters, however I think Stages have done enough testing to compensate for this.
If you are right, pedal based powermeters must the worst.
Of course, Stages have more or less got it dialled now, with the exception of the SNR which is still quite low. The non symmetry is the main cause for the dodgy readings of most dual sided shimano crank PMs. I think 4iiii has a better gauge layout (which I think they patented) for crank arms.
grease on the chainring bolts? I would think blue threadlocker if anything
What are your thoughts on pedal based meters for mountain biking? There are only a few choices(Garmin, SRM, modified Assioma SPD) but with how often pedal strikes happen in some terrain it seems like a very expensive system that will inevitable be destroyed/damaged.
Exactly, for me its just not an option. The state of my pedals!
Hi, tommorow i want to by specialized sl5 from 2016 with di2 rim brake for racing. Is this bike will be stil stiff?
Thanks for the vidéo. I have 1 question: what is the length of the screws? Thank you
A+ but lose one mark for not having lime green anodised chainring bolts ;-)
Shame it isn't easy to source a powertap hub and compare accuracy with the spider. Surely a hub based solution is the ultimate in protection from damage from the surface.
Could pedal strike snap those "ligaments " leaving you high and dry? Is there a fail safe limit to movement in that unlikely event?
Theyre about 15mm x 4mm thick Aluminium, so still pretty solid!
I have three of the NGeco units and they have been flawless. Prefer the coin cell battery as I would be fearful of the plug in version suffering from battery drain after a few years.
What happened to the Rotor crankset, that you baked together with your christmas dinner?
Thats for the road bike
I would run a one up components for shimano chain guide on the top rather than reverse the top bolt.
What do you think of the Infocrank?
Very good.
+ 256Hz sampling rate
+ forged cranks
+ decent full bridge gauge layout, easy to cancel parasitics & tune mV/V output of the circuit.
+ works with 24mm BB
- Weight (if you care about that).
- cost
- minimal chainring options
I have 3 power2max Gen 1,2,and 3 and still going, with no problems💪🏻but don’t have a mtb one
Thanks for the great video. I have a burning question to ask you. My cycling GPS has a recording cycle of 1hz, When a power value is transmitted and recorded, is that value an average value for one second from many samples or an instantaneous value based on one sample? When I look at my power data the individual numbers are all over the place. This makes me think that my PM (Stages) has a sampling rate of 1hz. You mentioned that the Infocrank has a sampling rate of 256hz. What about P2M and Stages? Where do you find that info.? I have a P2M on order and I would like to know. 256hz is probably overkill but I think 1hz is way too low!
I am pretty sure the P2M samples torque at 50Hz. I am not sure about the angular velocity sample rate. But yes the Garmin will only output 1Hz and this is really the limiting factor. As far as I can see, the sampling and recording rates are not the only important distinctions either, as no crank/pedal based power meter actual calculates power based on a fixed time sample, rather power is calculated on a variable duration event basis, that being the time taken to complete a full revolution of the crank. The power meters and/or head units (which depends on the model of meter) then take this variable duration power data and “force” it into a fixed duration recording rate.
It's average value from many samples (1s rolling average). Why would you like to have higher sampling rate on head unit? You'd see your power fluctuating horribly during every pedal stroke... Power meters usually transmit at 4Hz but most head units record it with 1s intervals.
@@michwoz Thanks Michal. What is weird is that when looking at the 1hz rolling average samples my power is all over the place. This is an observation made on both Quarq and left only Stages. The Stages fluctuates more than the Quarq due to the left side only. But even with the Quarq it fluctuates a lot. On my Garmin head unit I have 3s. avg. and 30s. avg., and I mostly look at the 30s. avg. value. The 3s. avg. fluctuates a lot and it's mostly useless other than for a sprint. I wonder if our power output really varies this much due to a lack of a flywheel effect when we pedal.
@@jonathanwoo6597 Could you please describe what "all over the place" means for you? Power does in fact varies between pedal strokes. For some people more, for other less. I've seen a lot of different people power graphs and it may fluctuate A LOT. It's more about pedaling technique than power meter sampling or any hardware issues. Humans are not robots. At least most of them. There are people who can maintain very steady and stable power graphs, but they are minority.
Just bought garmin rally xc100s.. Not sure if I want to watch this video incase I regret my purchase...
Great video. Benchmarking: I'm not so sure if readings from Favero Assioma pedals should be trusted so much that the readings can be taken as a ground truth.
I own eight power meters, and they are all very consistent, which is very good. The power meters that read a little lower than the others always do so. But which power meters give the best readings? We always want the truth.
Currently I have three power2max units (two Type S, one Classic). Very consistent readings - the readings are about 1.5 percent different, but always in the same pattern. Of course two spider power meters can't be compared simultaneously, but I found this by comparing to a Direto X trainer, which is also very consistent at a given offset value.
To the Favero Assioma DUOs. They read 2-4 percent higher than the p2ms, and also 2-4 percent more than two SRMs and a Powertap hub. It reads approx. the same as the Direto X.
I think Assiomas are very sensitive to angular calibration. To get a good alignment during calibration, I hang a coin from the pedal axle and align the crank arm so it is angled straight upwards.
This makes repeated calibration after several rides necesssary as the pedal axles get more and more tightened to the crank arms.
By comparing power meters on the Zwiftpower tool, the Favero Assiomas have some spiky fluctuations in the readings. Not so bad for averaged readings, but it seems like something is off.
n=1 for my experience with Assiomas, but p2m might just as well give accurate readings. I trust my p2ms more.
The Assioma pedals need to know the angle of the crank arm to decompose the force vector. The reliance on accelerometers might introduce an extra source of error. For oval chainrings, this technology is probably very well suited, though.
I might be wrong, it would be interesting to hear your opinion - maybe in a future video?
Great comment, yes will talk about these things hopefully in the next one after I have tried the Assiomas!
I love spider based PM's. I shouldn't be riding Campag, that's another convo, but since I do, I wish P2M sold their 5 arm campag model to the US.
I used to watch Hambini at x1,5, now it is applicable to PQ - this is the trend I don't really want to fall for...
Too bad shimano does not have the same crank design on their roads as on MTB. The non spline shimano connection seems to be better than the splined rotor cranks that I have on my road bike (however no issues to report so far luckily).
i wish shimano made a road dm crank
Why does nobody think about people that want to run a 30T or 28T chainring? There are no dual sided solutions in that case.
Also, regarding better being off at anything lower than 34T, even a 30-50 combo is still faster than walking, And easier, as you're not pushing something along with you, the posture is much better, etc. I find it REALLY funny that people actually prefer walking to riding steep climbs. I'm out there to ride bikes, not to walk. And around here the climbs are steep. So steep I've often thought it's be nice to have a 28-50 combo instead of the 30T.
I do prefer to have a slightly higher cadence than some people, but still, I can manage 1000 VAM on gravel on a 16kg bike with 2,5WT tyres at 1,5 bar. I really need a power meter to see what I'm putting out :D
Totally agree, MTB gearing is done wrong imo. I'd rather not walk extremely steep stuff (and I'm quite a climber ~5wkg). The standard 32t is like road bikes being fitted with 53/39's....which aren't popular anymore
There’s no way I’d replace that bombproof Shimano spider with that flimsy item. I’ve seen numerous third party spiders fail catastrophically and that doesn’t look safe.
Pedal based: Garmin Rally XC?
They're not good mate 😕
If you saw the state of my mtb pedals, you'd understand why i think they wouldn't last very long on my bike 🤠
@@PeakTorque For completeness: There are also SRM x-power SPD pedals. Have used mine for a couple of races - so far no problems but let's see in one year.
@@saynotothegreatreset I had a battery door vibrate loose on my vector 3 pedals during a road race and lost the battery; it felt like driving a car with no fuel gauge at that point.
@@PeakTorque I use Garmin Vector 3 on my road bike, but hesitate to use pedal based on my MTB. Looking forward to your conclusing on the Power2max. GPLama has a review og the Sigeyi. I guess you've seen that?
Are power meter pedals not worth it?
You are more likely to bash pedals on rocks etc when mountain biking. You may not want to risk damaging power meter pedals as they are more expensive to replace than regular pedals.
If you are worried about chaindrop buy a Gabaruk chainring. Longer teeth.
Hang on there. Aren't all movements and forces due to power applied to the crank arm? I know it's not what we want to measure, but one could argue that we could measure the actual power output of your legs, rather than the power applied to the drive train!.....
Ok, I know it's kind of stupid... But hey... Thi K about it 😂
First!
so you are big boy now?
Idk why I even took all my FEA and design of machine components classes, I could just watch peak torque lol
I understand that you dislike the gxp system and have made videos about why, can you make an update on how you feel about the new dub system has Sram redeemed them selves in your eyes
I dont mind gxp, if you get a crank that is well made. I have run a quarq gxp powermeter for 5yrs with no problems in the same sram pressfit gxp BB.
Power meters aren't that common for MTBs because there's very few Freds who care about KOMs. Harsh but that's the way it is.
I use the MTB for training, and fun.
True, but since I have powermeter on my roadbike.. I wanted powernumbers on my mtb. I went with the favero assomia duo spd hack for my Mtb..works fantastic.. they can handle a lot of abuse as well
GAINS MUST BE QUANTIFIED
I think you are so wrong, XC bikes are sold and raced (big junior scene in the US)
No shit. Thanks for the bleeding obvious.
🙃 Made in Germany 🙃
If you're not racing MTB then this all seems ridiculous to me.
Why? Power meter is more useful in training and tracking your numbers (TSS, calories) than actually racing. You can race without PM, many don't even look at watts during races. But not having PM on MTB bike makes your total data incomplete. And many people care about that.
quite the opposite - in general I race mostly gravel and some road races (with poor results, but that's to be expected) and I use my MTB to have some variation in training. A PM is very useful for training - you can watch the power and make sure you don't over exert yourself on the off/recovery days.