Hi all,
there are reports a config as in the subject line is totally successful but I am totally unable to get it working perfectly.
Setup:
BMC TM01 2013 frameset
Ultegra 6870 Di2
ROTOR 3D+ crankset with 54/42 Q-rings
KMC 11X-SL chain
rear shifting works perfectly in all conditions
front shifting works perfectly when bike on the stand (no load applied to the pedals). When on the trainer/road the shifting from small to big ring does not work well - pressure onto the pedals need to be decreased significantly for the shift to happen; otherwise the chain continues to slide on the big ring (tak, tak, tak, tak, tak, …).
The only potential issue I see is that outer ring seems to be quite a distance from the center of the crankset - micro adjustment of the FD is all the way to outside
Any pointers are hugely appreciated
Limit screws. Just had similar issue yesterday.
First set the low limit, make sure it’s barely not rubbing in your lowest (ie small front largest sized cog on back, eg 42x25). This gets you started in a good position.
Then adjust the high limit. It should be barely not rybbing in highest (eg 54x11). I didnt realize that the limit is increased (viz, more movement outwards) by tightening the screw.
Thx, I’ll give it a try later today
.
The limit screws were on the money. No adjustments to the limit screws helped in any way :-(. As a matter of fact with the high limit being set at “just touch” I was not able to shift onto the big ring under the smallest load at all. It had to be at least 1mm. It seemed to be the auto-trimming mechanism that was messing up front shifts onto the big ring (big move to the outside and tiny move to the inside to adjust).
Anyhow, I decided to try the standard 53/39 Q-Ring setup and there is no problem shifting with these rings on the TM01/Di2 :-). I might not give up yet on the 54/42 and try it again after this Sat race.
BTW, 53/39 shifts and feels incredibly great on my road bikes with Red 10 and 11 speed - an upgrade well worth the effort and $.
Cheers
Sorry that i wasn’t able to be more of help. The only other thing i could think of is derailleur height. I know there’s a deifference going from 50->52t, but not sure how big an impact there will be from 53->54t.
Definitely no need to be sorry. I appreciate the help and pointers. echappist, what size rings do you use? and do you have Ultegra or Dura-Ace?
I think I saw a post someplace indicating that Ultegra Di2 will work with 53 ring max; but someone reported good functionality with larger ring (round). Well, in case of Q-Rings the 54 is equivalent in spots to probably 56 or so so maybe this is an issue.
I played with different FD heights - from almost 0mm through .5mm, 1mm, and up to 2mm (this was the highest I could go on my built-in FD hanger without dremel :-))
I will try installing 54 Q-Ring and getting it done once again and will report on the result.
Cheers
Have you thought about trying the Rotor shim/spacer kit?
For my QXL rings on my TT/Tri bike, without it I couldn’t get my front derailleur high enough to clear the big chainring (53t even for the qxl). They come with QXL rings standard though but you can buy them separately from their website.
I have 54/39 Q-rings in a P3 with Ultegra Di2. I do not have any problem shifting with the FD, but I cannot get any lower than the 15 in the cassette when I’m in the small ring because of the height of the FD. It is set pretty high and I even used the little Rotor adaptor to angle the FD. The cage is way shorter than the regular Ultegra FD.
Interesting. For me the height of the FD (clearance) was never the issue. I will report again once I put everything together. Thx for the replies
It might be an issue for me because I have the 39 instead of the 42 that you have.
Quick update
the ride on 53/39 was OK but was not perfect - shifting of the FD required easing up a bit on the cranks. But the Q-rings on TT (TRI) bike feel fantastic and:
even though I picked a fairly rolling run I had to shift the FD rarely
shifting FD from low to big can be done at lower power compared to big-to-small (base of the hills) - so not an issue
TM01 is incredible!!! I was on a slightly oversized Jamis TT bike before and felt quite good but TM01 is like on rails: so precise, so solid, so planted. I felt as there might be more then a few occasions where a larger ring will be beneficial
And so I switched to the 54/42 again. Doing everything by the book and the same thing - FD shifting (small-to-big) under power REQUIRES (in my components setup) significant easing up pedal pressure. But doing a test ride today proved that it can be learned easy and without major hassle. Yes, several down-shifts will drop you a second or two but I BELIEVE that Q-Rings and bigger ring setup will add these couple of seconds even in a short TT
We will see tomorrow. Icebreaker TT. Unfortunately nothing to compare to as I’ve never done this one but my comp is more than solid- 21:53:45 - 10 miles (5+5) last year winner in my cat - this is fast!!!
BTW: love the electronic on the TT. Previous Red required some effort while shifting on the aero-bars and (obviously) no pursuit shifters. My road setup is mech thou 
and I love it.
Cheers