Most light weight powermeter?

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refthimos
Posts: 411
Joined: Fri May 25, 2012 6:02 pm

by refthimos

dalex wrote:
Wed Jul 18, 2018 9:13 pm
AndreLM wrote:
Wed Jul 18, 2018 8:11 pm
SRM Origin (I have seen different weights online, but not sure if it was for 24mm or 30mm version)
Mine: 662 g all up (30 mm axle, both cranks, Shimano Dura Ace 52/36 rings)
Seems fair to compare crank-based PMs based on arms, spindle and spider and not rings, since those can be swapped. Yes DM rings throw this off, since you lose the spider but then have to adjust with the rings, but I'm not sure there are any crank-based PMs that actually use DM rings (e.g. with the SISL2, you add a PM spider and use normal rings, not DM rings) so I think arms + spindle + spider is a fair way to look at this.

So if those are the ground rules, I believe your Origin would weight approx. 532g (I'm deducting 130g for the Shimano rings). That is just an estimate - I am sure one of you knows the numbers better than I do.

For a SISL2 PM, my research estimates 250g for the arms, 64g for the spindle, and assuming we go with a P2Max NG (not ECO), 157g in 110BCD. That adds up to 471g, or approx 61g less than the Origin. Not sure if the SRM spider for Cannondale cranks is more or less than the 157g for the ECO, so there may be an even lighter SISL2 option yet.
EVO1 | 5.37kg
EVO3 (sold) | 6.51kg
EVO4 | build thread coming soon
S5 Disc
SystemSix (sold) | 8.01kg
P5 Disc | heavy but fast

refthimos
Posts: 411
Joined: Fri May 25, 2012 6:02 pm

by refthimos

AndreLM wrote:
Wed Jul 18, 2018 8:11 pm
A SiSL2 with SRM or P2M is probably one of the lightest, but it is limited to BB30/PF30 frames. Another BB30 alternatives, that are potentially even lighter, and still dual-sided:
- S-Works power crank (with factory-installed 4iiii pods)... for now I think they are only available with new Tarmacs and Venges...
- SiSL2 with Watteam powerbeat pods

(I am not saying they are as reliable as SRM or P2M though...)

Other lightweight spider-based options:
- Easton EC90 SL with P2M NGEco spider (BB386... compatible with everything but Trek BB90)
- THM Clavicula M3 with SRM (BB386... but discontinued?)
- SRM Origin (I have seen different weights online, but not sure if it was for 24mm or 30mm version)
You're right! The S-Works power crank should definitely be a little lighter than a SISL2 w/ SRM/P2Max. That should be the new crank PM to beat, assuming the actual weight is near the 440g claimed for the 172.5mm length.

For me, it's hard to take Wattbeam seriously, solely on the basis that they look super goofy (IMHO).
EVO1 | 5.37kg
EVO3 (sold) | 6.51kg
EVO4 | build thread coming soon
S5 Disc
SystemSix (sold) | 8.01kg
P5 Disc | heavy but fast

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AndreLM
Posts: 479
Joined: Tue Feb 05, 2013 11:53 pm

by AndreLM

I know a guy with an S-works SL6 disc (with the power cranks)... I am trying to convince him to take out the cranks so I can check if they fit my frame (the pods are faily chunky). I will post scale shots once I get to weight it.

KevinM
Posts: 58
Joined: Fri Jun 29, 2018 11:37 am

by KevinM

Stueys wrote:
Wed Jul 18, 2018 8:24 pm
KevinM wrote:
Wed Jul 18, 2018 3:46 pm
claus wrote:
Wed Jul 18, 2018 1:58 pm
KevinM wrote:
Wed Jul 18, 2018 11:05 am
The thing about power data is that the numbers only matter as long as theyre consistent.
And then you switch to a new/different power meter... and all the old data is now probably useless.
Exactly! All that matters is the meter you’re using is consistent.
As long as you don’t want to use a smart turbo with inbuilt power meter, or get another bike with a PM, etc, etc. Accuracy and consistency are both important.
You’re fooling yourself if you think there is a smart trainer or pedal or crank or whatever that is more “accurate”. Even two pairs of the same model power meter aren’t exactly the same. If you’re going to use two different power meters (I do: Neo and P1 pedals) and you’re worried about 1% variance, just have two FTPs. Comparing your FTP on a pair of Vectors to my FTP on a different set of Vectors doesn’t make sense. There will always be variance. Until we can both ride on the same exact meter set up with the same exact bike, we’ll never know.

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ms6073
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Location: Houston, Texas

by ms6073

KevinM wrote:
Fri Jul 20, 2018 4:05 pm
I do: Neo and P1 pedals) and you’re worried about 1% variance, just have two FTPs.
Not that I really need a powermeter anymore, but I ahave a Shimano R9100-P (previously SRM DA-9000) and Tacx Neo. While neither are ever going to be in exact agreement, the powermeters and the Neo are on average usually within +/-2% of each other. The one time I overlaid the SRM and Neo power graphs, they were nearly mirror images between the Neo and SRM.
- Michael
"People should stop expecting normal from me... seriously, we all know it's never going to happen"

Hoven
Posts: 146
Joined: Mon Mar 04, 2013 7:30 am
Location: Sweden

by Hoven

What powermeter incl chainset would be the lightest? 46t chainring that will be used with Sram axs, spiderbased. Have a Hollowgram si 175mm with a p2m Type s at the moment, would a Red qaurq Axs dub be lighter?

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neeb
Posts: 1101
Joined: Tue Jan 27, 2009 8:19 pm

by neeb

KevinM wrote:
Fri Jul 20, 2018 4:05 pm
You’re fooling yourself if you think there is a smart trainer or pedal or crank or whatever that is more “accurate”. Even two pairs of the same model power meter aren’t exactly the same. If you’re going to use two different power meter s (I do: Neo and P1 pedals) and you’re worried about 1% variance, just have two FTPs. Comparing your FTP on a pair of Vectors to my FTP on a different set of Vectors doesn’t make sense. There will always be variance. Until we can both ride on the same exact meter set up with the same exact bike, we’ll never know.
I'm content that all three of my PMs (two P2M NGs and a Powetap hub) are within 1% of each other, having tested them together (each P2M against the PT). To me this is very important, I'd hate to have to be bothering with different FTPs on each bike and not knowing how to interpret power curves etc with data from multiple bikes.

I actually think that PM accuracy is greatly underrated by most people. Especially as the most accurate meters are accurate enough (1%), while most PMs on the market (with accuracies of 2% or less) aren't really.

PS I've had other PowerTap hubs that weren't as accurate - lucky with the one I've retained. Both my P2M NGs seemed to read the same out of the box, I tend to believe the claimed 1% accuracy.

Hexsense
Posts: 3270
Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

KevinM wrote:
Fri Jul 20, 2018 4:05 pm
If you’re going to use two different power meters (I do: Neo and P1 pedals) just have two FTPs.
Uhm I even have two FTP measure indoor and outdoor for the same power meter...
It's about wheel innertia and lock in place bike position that make my outdoor power and my indoor power not the same even when measure with the same power meter.

There should be different FTP for indoor and outdoor and different bike position (TT maybe lower than road etc.). But different bike with identical position riding on the same condition should be consistent.

3Pio
Posts: 1581
Joined: Wed Mar 09, 2016 7:13 pm

by 3Pio

KevinM wrote:
Fri Jul 20, 2018 4:05 pm
Stueys wrote:
Wed Jul 18, 2018 8:24 pm
KevinM wrote:
Wed Jul 18, 2018 3:46 pm
claus wrote:
Wed Jul 18, 2018 1:58 pm


And then you switch to a new/different power meter... and all the old data is now probably useless.
Exactly! All that matters is the meter you’re using is consistent.
As long as you don’t want to use a smart turbo with inbuilt power meter, or get another bike with a PM, etc, etc. Accuracy and consistency are both important.
You’re fooling yourself if you think there is a smart trainer or pedal or crank or whatever that is more “accurate”. Even two pairs of the same model power meter aren’t exactly the same. If you’re going to use two different power meters (I do: Neo and P1 pedals) and you’re worried about 1% variance, just have two FTPs. Comparing your FTP on a pair of Vectors to my FTP on a different set of Vectors doesn’t make sense. There will always be variance. Until we can both ride on the same exact meter set up with the same exact bike, we’ll never know.

Hmmm.. If one use exactly same model on two bikes, let's say Favero Assioma Duo (measuring both sides).. U think still there will be variety between both pairs even they are the same? If yes that mean if someone want real accuracy in data collected from Power Meter, then only option will be switch same pair from one to other bike? Perfect if someone tested two or more different Favero Assioma Duo pairs each other, i really wonder if they vary from one pair to other

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