Magene PES P505 base powermeter very poor upshifting

[carbonbuyer]

Hi!

I recently purchased the P505 base powermeter, and the powerreadings seem to be quite good, but the upshifting on the front mech is god-awful.

Previously i could upshift under insane amounts of torque super sharply. Right now even when putting out 100 watts, the chain will not upshift! only when applying almost zero torque and then pedaling (under 80 watts) will it upshift.

My setup: SM-BB72 bottom bracket
Ultegra R8100 DI2 setup

I had to adjust my Di2 from +0 to +12 for the system to upshift to the big ring at all. Chosing a higher number is not possible since then there's chain rub. I even decided to make the chain rub a bit when using the biggest cog of the casette, to make the FD push the chain even more towards the big cog, but no luck.

I'm using the shimano chainrings i used before (ultegra 52-36 or smth like that)

Any tips/solutions?

[SirBikealot]

Hi!

I recently purchased the P505 base powermeter, and the powerreadings seem to be quite good, but the upshifting on the front mech is god-awful.

Previously i could upshift under insane amounts of torque super sharply. Right now even when putting out 100 watts, the chain will not upshift! only when applying almost zero torque and then pedaling (under 80 watts) will it upshift.

My setup: SM-BB72 bottom bracket
Ultegra R8100 DI2 setup

I had to adjust my Di2 from +0 to +12 for the system to upshift to the big ring at all. Chosing a higher number is not possible since then there's chain rub. I even decided to make the chain rub a bit when using the biggest cog of the casette, to make the FD push the chain even more towards the big cog, but no luck.

I'm using the shimano chainrings i used before (ultegra 52-36 or smth like that)

Any tips/solutions?

maybe a supid suggestion (i have to admit i did it myself) but is the small chainring upfront mounted in the correct direction? Had some similar problems which where solved by turning the small in the way it should be.

[carbonbuyer]

yup it's in the right direction and right way up (though that last part was by accident, only when researching yesterday did i find out that one is directional as well).

I even tried flipping the front chainring, but then the chain falls in between the two chainrings sometimes..


Also that still doesnt explain why i would need a +12 adjustment, which is wayyyy to much IMHO (that messes up the chainline bigtime)

[carbonbuyer]

Magene support is at least very responsive on aliexpress. Now they want to know what frame i have. How that will affect anything, i'm very interested (since it uses the standard external shimano BB, and standard shimano r8100 crank)

[James dean]

when a fd wont shift upwards its usually never the crank. Its 99.9% the fd is set up wrong

[carbonbuyer]

when a fd wont shift upwards its usually never the crank. Its 99.9% the fd is set up wrong

That clearly is not the case though. The chainline is so far offset to the outside that when having the chain in one of the 4 biggest cogs on the casette and then backpeddaling, the chain falls off. That clearly is an issue with the crank, and not the FD, since the FD has nothing to do with backpedaling. And that the FD required a +14 offset to upshift at all is also a good indicator that the crank has a bigger offset than the regular shimano crank.

I'm not discounting the fact that i misinstalled the crankset or blades in any way, it's just that I cant figure out what it would be...

[Ultramic]

It's not you it's the crankset. I had the same issue with my 105 Di2 groupset, the inside crank arm was actually striking the derailleur (I would check your crank arms too). Managed to get a partial refund from magene, now it's just sitting on the shelf.

[Bigbobby1482]

It's not you it's the crankset. I had the same issue with my 105 Di2 groupset, the inside crank arm was actually striking the derailleur (I would check your crank arms too). Managed to get a partial refund from magene, now it's just sitting on the shelf.

I have a fully working setup with magene pes crankset and 105 di2. You need to run the FD's H limit less then 1mm to the crank, and set the synchro shift in the  E-tube app to be max outboard in all shifts.
Shifting is fine an no chain rub