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Magene P505 PES Base Spider Powermeter
Sebastian:
Powermeter pedals and the Spider based powermeter both measure before drivetrain losses. Both have a claimed accuracy of 1.5%. The deviation I think I’m seeing is more though. BUT - I had the Magene on my gravel bike and the Assiomas on the road bike. First time ever that I’ve used a PM on gravel so no data to go from and it might just be that my rides off road were harder than on road. Now that I moved my Magene to the 2nd road bike, it’s actually closer to my Assiomas. But it still seems higher. Need to put the Assiomas on there and compare the readings directly but so far I just couldn’t be bothered.
Eddy_Twerckx:
--- Quote from: Sebastian on November 19, 2023, 02:52:51 PM ---I got the P505 in the SRAM 3 bolt variant on my Red crankset. I think it’s slightly overreading compared to the Assioma pedals on my other bike. I could scale it down in the app but I need to put the Assiomas on the bike to compare them directly. Other than that the thing is bomb proof.
--- End quote ---
Oval rings by any chance? My Magene on oval rings reads higher than my Assioma. On round rings they’re within a watt. It’s easy enough to scale down once you get an offset from testing.
nickobec:
--- Quote from: TidyDinosaur on November 20, 2023, 07:15:46 AM ---Well, you have the drive train losses between crank and hub... Maybe that can explain. I find 2 % still VERY good.
--- End quote ---
Testing I did with the older of my Powertap G3 hubs, Sigeyi AXO spider and Favero Assioma pedals was 1% between all 3 power meters. It was steady state longer rides. Somehow the Powertap even with drive train losses (it is a efficient drive train) was really close to the crank and pedals readings.
My newer Powertap G3 hub compared to the Favero Assioma pedals was out by a little over 2%, but with a little digging, retesting and calibrating. It is close to 1% for steady state rides. However, sprints (or hard efforts) both Powertaps over estimate my power (say 5% for 1 minute all out).
Sebastian:
--- Quote from: Eddy_Twerckx on November 20, 2023, 11:25:14 AM ---Oval rings by any chance? My Magene on oval rings reads higher than my Assioma. On round rings they’re within a watt. It’s easy enough to scale down once you get an offset from testing.
--- End quote ---
Nope. Regular round rings. I’ll give it a go on the turbo in the next few days and report back what the offset is. Or maybe it was just my subjective feeling.
Sebastian:
So I put the Assiomas on the bike. I did a ramp test and a quick workout in Zwift and recorded both the Magene P505 and the Assiomas.
The Magene consistently overreads by around 5% while the cadence is pretty much identical on both units. I did a zero calibration with both units prior to comparing them.
I adjusted the power scaling accordingly in the Magene Utility app. I'll give it another go shortly to see if I can get them to match up.
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