HI everyone, I’m having a weird issue with the front shifting on my 12 speed Di2 bike after installing the Magene PES P515 power meter with the magene QED chainrings. I’ve set my FD up from scratch again multiple times and continue to have the same issue when I shift into the big ring where more than 50% of the time the chain sits on top of the teeth instead of actually going into them for at least 1/4 of a crank revolution. At first I thought it might be a worn chain on new chainring so replaced my Ultegra chain with a new one but it still happens. The shifting up is also a bit clunkier than it was on my previous Ultegra chainrings but I originally just thought that was because third party chainrings will never shift as well as a full shimano drivetrain (everything else is stock Ultegra R81x0). I’ve also tried simply increasing my H limit to be higher than what Shimano recommends and it doesn’t improve anything, just risks the chain going too far and falling off the outside of the chainring.
Hard to really tell without seeing the bike itself. Plus, you’ve done all the right steps with the full reset. I have for years run wonky noon-standard chainring combos (such as my 34-52 on my gravel bike). So, lucky me, I have plenty of experience tuning front mechs. If it was my bike, here’s a couple thoughts: Make double-sure that the cage is within the 1-3mm height of the chainring since that hight matters a lot. Micro-adjust the FD cage angle. Sometimes that tiny tweak is all you need. And (final option) bend very slightly the front of the inner portion of the FD cage. Be super careful not to over-do it.
Hope this helps.
Thanks for the advice, I might continue to play around with the angle of the cage since that was the area I was least sure of my work. I’ve dropped the cage to be only a bit over 1mm above the chainring and sadly that didn’t do anything. If all else fails I might put my old shimano chainrings back on and set them all up from scratch (they’re a different size than the new ones so I had to adjust the height) and see if I can get those to work easily or if they have the same problem.
One possibility could be chainring spacing. Pull the crank and check your spider/chainring bolts. If your outer ring is sitting more outboard than your old Shimano crank, you aren’t going to be able to adjust that out. Could either be an issue from when the rings were mounted to a QA issue with the Magene spider thickness. Completely remove the rings and re-mount them. If the issue persists, it might be worth it to put the rings back on the old crank, measure their spacing, and compare to the ring spacing on the Magene unit.
I switched to a Magene PES P515 crankset last summer. I’m running Shimano chainrings mounted to the Magene powermeter. Rest of the drivetrain is 9100 mechanical. My experience has been that the chainrings sit further outboard on the Magene crankset than they did on my Dura Ace crankset. The result is funky chainline. With the Dura Ace crank, I could crosschain all the time without issue. The Magene is much more sensitive to chainline. I’ve learned to work around it. Thought I would share as an additional data point.
Thanks for the info. From what I’ve seen online Shimano 11 and 12 speed have slightly different chainlines and the Magene PES power meter is between the two. The weird thing is that adjusting my H and L limits doesn’t make this problem any better or worse, where I would’ve assumed that if it was simply about chainline I could’ve found one direction makes the issue better or worse.
Is it possible to mount the chainrings with the indexing incorrect?(unlikely on Shimano 4-arm stuff). It sounds like the ramps on those chainrings are bringing the chain up slightly out of phase with the teeth.
I considered this option but it appears I mounted both chainrings correctly. Once it’s in the big ring it’s snug and there’s never any problem downshifting.
Sounds more like an chainring issue rather than derailleur issue. I would definitely reach to Magene or anyone who sold the rings to you and in the meantime you can try compare/measure the original rings to the Magene ones. Width, pitch, spacing on the spider (as suggested above). My bet is the teeth are marginally wider hence it takes a bit force to engage the chain fully. It should be better as the chain wears down the ring 
Thanks for all the suggestions. I sent an email to Magene explaining the problem and in the meantime I am going to try and switch my old Ultegra chainrings onto the power meter and see if I can get that to work. If I can I will just assume its an issue with the chainrings themselves.
I’d reach out to @GPLama . He’s tested Magene PMs, and his testing is always thorough. I think if there’s anyone that has experienced this or has heard of other experiencing and knows how to address it…it would be him.
fwiw I also run a Magene PM with my stock Ultegra chainrings and have zero issues. There were a few fine alignment things for my bike shop to sort out from memory but I don’t remember the details.
Shimano chains are directional. The text on the chain should be facing the driveside, that might make it shift a little bit better.
Thanks everyone for the help. After fully removing and reinstalling everything I got it shifting a bit better in the stand although not 100%, but I will reserve judgment until I’ve ridden it on the road. Really fine tuning the exact angle of the FD and getting the height as close to 1mm above the big ring without going under seemed to help a bit. The chain is facing the correct direction but I really don’t think it’s a chain issue since it has happened on two different 12 speed shimano chains (one ultegra one dura ace)
I guess to rule everything out, if you put your old Shimano cranks and chainring back on does it shift correctly?
The front derailleur is a pretty crude mechanism, the real shifting happens between the chain and chainring. The profiling of the chainring teeth, the offset between big/small rings, gap between rings, chain/chainring wear matter a lot.
Think of the front derailleur as just giving the chain a shove in the right direction, and then it is up to all the other factors if the chain lands in the right spot.
An ideal shift is where the chain is fully engaged on both chainrings simultaneously. In the case of the photo above, it looks like an issue with a chainring that is worn with a newer chain. The small chainring is worn so the chain sits in a different spot than it normally would and now the distance between the tooth on the small ring and the tooth where the shift ramp is no longer is a multiple of 1/2” (the length of a chain link).
Here is a blog post about designing chainrings to work together (Rene Herse 11-speed Chainrings in New Sizes – Rene Herse Cycles)
A final update: After many more attempts of slowly resetting the height and angle of the FD I finally got it to consistently perform similarly to how it was previously with my full shimano drivetrain. I’d definitely echo what @jasedepuit said about how it takes some fine alignment (specifically the angle) to get it into a good operating window but once you have it there it performs fine. Some of my shifts are so smooth I had to look down on the first few ones to even confirm it shifted.