Magene P505 PES Base Spider Powermeter

[Nicoloc]

I t looks like mine died today after a little less than 2 years.
I'm in contact with customer support as it still in warranty period....
We will see how mMagene react ....

[BerndSon]

Same issue here, the big bolt always gets loose over time, left crank arm then travels outwards.
Luckily i always recognized it in time before anything separated
Tried to fix it several times, checked torque, cleaned everything, used thread locker, without any success.

Thought this might happen to me since i use it out of spec, - on a gravel bike with GRX setup. In Order to get the front derallieur working, maintain a functional chainline and keep everything symmetrical, i used 2mm spacers on each side of the BB, resulting in 4mm less "clamping surface" for the left crank arm.

After reading several reports here, it seems thats not what causes the issues.

Hope i can find some time to dig a bit deeper into this issue soon an will report here in case of any interesting findings...

[ejump0]

So on my morning ride the left crank arm came off. It started feeling a little wobbly and I was hoping to make it to a lit area up the road to stop and check it out. Didn’t make it. Came off and lost the bolt as it was still dark out.

I tightened the crank arm bolt and was able to make it home.

I have a gravel event this weekend I’d still like to do. Am I risking damaging the power meter if I ride it without the big bolt that goes into the spindle?

Edit: changed to non obnoxious pic size.

Do you have access to get Shimano's hollowtech2 big bolt?
I remember testing my R7000 bolt, and seemed to fit (onto the p505 base spindle) and the lip go ever the crankarm a bit.
Granted shimano's is plastic, better than nothing

[SillyMochi]

Reading all your "horror stories" of loosing that bolt, I just checked mine as I have a event coming up. All screws (clamp, "big" bolt, "small" inside bolt) were absolutely fine and still at the correct torque. If I remember correctly my 2-piece-bolt came with some thread-locker pre-applied. Maybe that's a newer generation and they improved on the issue?

[gloscherrybomb]

Mine is pretty new and my left crank came off completely at British gravel champs. It was torqued to the exact Magene specs. I've reached out to Panda Podium for a replacement preload bolt.

[00Garza]

Do you have access to get Shimano's hollowtech2 big bolt?
I remember testing my R7000 bolt, and seemed to fit (onto the p505 base spindle) and the lip go ever the crankarm a bit.
Granted shimano's is plastic, better than nothing

Didn’t know that fit! I’ll give it a shot with some local shops.

[00Garza]

Local shop fitted a shimano preload bolt no problem.

[SirBikealot]

I lost mine two weeks ago midsprint… Luckily on the bottom of the stroke so i didn't crash. Wrote Magene and they offered me replacement in case i take the transport fees. Ordered two just in case. But only one arrived because of "due to a warehouse shipment error". I now secure it ontop off loctite and correct torque with a peace of duct tape.

[maxilon]

Mine is pretty new and my left crank came off completely at British gravel champs. It was torqued to the exact Magene specs. I've reached out to Panda Podium for a replacement preload bolt.

Same here. I brought the whole system including cranks and chainrings. No matter if I used different spacers or even mounted it on different bikes the left crank arm gets always lose after a few kilometers. One day it even fall completely off. I was just happy not crashing. After contacting the seller. I think it’s a mangene dealer on AliExpress (not Magene itself) they offered me a reparation on my own costs or a new screw only of I buy other stuff in their store. By the way the power data was always very fluctuating. Does anyone has the issue with sellers? Should I contact Magene directly?

[00Garza]

Local shop fitted a shimano preload bolt no problem.

Upon further review and discussion with local shop...the hollowtech bolt doesn't truly serve the same purpose as the Magene bolt. The shimano bolt is not really designed to take as much pressure as the magene metal bolt. It will either deform or lead to flex and eventual failure it seems. I had already contacted Magene, but haven't heard back.

[SillyMochi]

By the way the power data was always very fluctuating.

That's just how power meters or rather your body works: it near impossible to output the same wattage for any given period. Instantaneous power will always fluctuate quite a lot even if you are pedaling at a steady state and *think* you are applying even pressure. That's why we use 3s power for a quick glance or Lap AVG for the training target.

[kubackje]

That's just how power meters or rather your body works: it near impossible to output the same wattage for any given period. Instantaneous power will always fluctuate quite a lot even if you are pedaling at a steady state and *think* you are applying even pressure. That's why we use 3s power for a quick glance or Lap AVG for the training target.

Magene is quite fluctuating. I have to use 5s avg and 3s avg reading are too much over the place. I think that readings fluctuate little less on small chainring as far as I remember.

[SillyMochi]

I think that readings fluctuate little less on small chainring as far as I remember.

That's also normal. It has to do with (fly-)wheel speed. If the speed is higher (e.g. large chain ring), you have less time during the pedal stroke to apply the given power. It's more like every rotation you "top up" the wheel's speed with a short tap on the pedals. When the (fly-)wheel's speed is lower (e.g. small chain ring), you apply power more evenly throughout the pedal stroke. Therefore, it is easier to apply the same power with every pedal stroke as you already have a bit of power smoothing "built-in". BTW: That is also the reason why for some people 300W on a climb feels harder/easier than 300W on the flats. Has to do with your muscle fiber and which type is dominant in your composition.

Regarding whether the power of the Magene PM fluctuates more than other PMs: I compared it to my Assioma Duo. Over a 120min ride the AVG differed by 1% with the high and lows being very close as well. Basically the same; just as what GPlama found when he tested them about a year ago:

Code: [Select]

https://www.youtube.com/watch?v=62ucR_s_HQs

[Killeen]

Ive the Magene P505 PM with 165mm Cranks, but on the sensor details on my Garmin Fenix it states 172.5mm cranks, is there a way to correct this?

[SillyMochi]

If you cannot set this in your watch's sensor settings (like you can with most bike computers), go to the Magene Utility App and set the correct crank arm length there.