Magene P505 PES Base Spider Powermeter

[TidyDinosaur]

Coming back on your builds @TinyDinosaur, does it also work with a 2by crankset, i.e. 2 chainrings?
I suppose they would need to be 3 bolt as well?
My idea was building a 46/30 crankset with the riro cranks.

Yeah, I wouldn't know why that would not work. And indeed 3-bolt chainrings. You could look at the senicx branded ones.

[Greenred]

Yeah, I wouldn't know why that would not work. And indeed 3-bolt chainrings. You could look at the senicx branded ones.

That's very helpful. Is it correct to assume, that in a 3bolt 2by setup with the PM, the chainrings would need to be "one piece"? (as opposed to my experience with original Shimano 2by chainrings).

[TidyDinosaur]

That's very helpful. Is it correct to assume, that in a 3bolt 2by setup with the PM, the chainrings would need to be "one piece"? (as opposed to my experience with original Shimano 2by chainrings).

Yes, or you could use a spider adapter, but I guess 1 piece will be more conventient

[Greenred]

Thanks TidyDinosaur. How did you mount the chainring on your Riro crankset and the Magene P505 S1103? Are the 3 bolts of the crankset long enough to go through the holes of both the PM and the chainrings?

[TidyDinosaur]

Thanks TidyDinosaur. How did you mount the chainring on your Riro crankset and the Magene P505 S1103? Are the 3 bolts of the crankset long enough to go through the holes of both the PM and the chainrings?

No, it does not work like that. Either you install the 1-piece 3-bolt double chainring (so no PM with that option) OR you install the 3-bolt powermeter and than install normal chainrings to the powermeter.

[Greenred]

No, it does not work like that. Either you install the 1-piece 3-bolt double chainring (so no PM with that option) OR you install the 3-bolt powermeter and than install normal chainrings to the powermeter.

Got it! Would you know whether the small 30-46 chainrings can be really attached to the Magene Powermeter S1103? Seems like due to the small size of the 30t chainring it's not always guaranteed to fit because of the BCD?

Chainrings for reference: https://www.bike-discount.de/en/shimano-grx-fc-rx610-2x12-speed-chainring

[TidyDinosaur]

Got it! Would you know whether the small 30-46 chainrings can be really attached to the Magene Powermeter S1103? Seems like due to the small size of the 30t chainring it's not always guaranteed to fit because of the BCD?

Chainrings for reference: https://www.bike-discount.de/en/shimano-grx-fc-rx610-2x12-speed-chainring

No, that won't fit. You need 2 chainrings with bcd 110. I don't know if they exist in a cheap version.

[poyo]

Got it! Would you know whether the small 30-46 chainrings can be really attached to the Magene Powermeter S1103? Seems like due to the small size of the 30t chainring it's not always guaranteed to fit because of the BCD?

Chainrings for reference: https://www.bike-discount.de/en/shimano-grx-fc-rx610-2x12-speed-chainring

There are 46-32 chainrings from Stone that should fit.

https://de.aliexpress.com/item/1005005163392599.html?gatewayAdapt=glo2deu

[Greenred]

Thanks for all the answers! I was considering the 32-46 as well. In the end, I had the chance to grab some discounted premarket Favero spd PM Pedals for my gravel build and went down that route for a bit more versatility and flexibility. Nonetheless, I think the magene pm here works perfectly for me on my road bike and is of amazing value.

[sbellote]

hi! A nice opportunity appeared for buying the P505 S1078 locally - the 8-bolt 107bcd one
the chainrings I found plenty options on Aliexpress, but I cannot find 8-bolt cranks
you guys have any suggestion or budget options for the cranks?

I'm not looking to upgrade my powermeter (currently I have a Magene P325cs set), but this P505 S1078 is cheap so I'm considering
but if I'll have to buy a sram crank for the 8-bolt, then it ends up being too expensive and not worth it

[toxin]

only sram make 8-bolt cranks

[kubackje]

Hey guys how do you check pm with your indoor trainer, U use Erg for that? When I put my bike on my wahoo kicker in ERG training mode the magene pm shows around 10-15 watts less then kickr - so I need to put power slope in magene app at 105%. When I use it in normal mode then difference is not that big and power slope is around 102%. This is my first power meter and it is strange to me as all the reviews online say that pes p505 pm crankset is spot on. Any ideas what should I do? I did 5 spin backwards before measuring ofcourse.

[toxin]

Absolutely not erg mode, just a set, constant resistance

[kubackje]

Absolutely not erg mode, just a set, constant resistance

Thanks you my friend

[TidyDinosaur]

Absolutely not erg mode, just a set, constant resistance

Why not ERG? I use trainerday programs, so those are blocks of fixed resistance for several minutes. Why would I not be able to use that?
I checked my 4iiii left arm PM against my Zwift hub last week and it also was a little lower compared to the Hub. I set it to 103%.