I've got a 2006 R3, and I'm in the middle of installing the Di2 group. There is a slight interference at the front derailleur, between the top edge of the braze-on on the bike, and the wiring socket on the derailleur. To position the derailleur at the recommended clearance to the chainring, I needed to file the corner off the edge of the braze-on. I'm wondering if anyone else has encountered this issue?

I've heard of this, so it seems it might be a "known issue" but I'd be curious to hear what people have done to solve it. I'd be afraid to file very much - the R3 front derailleur mount looks thin already to me!

What size chain ring do you have? How big is the gap (manual says 2-3 mm I think)? 

Standard Dura Ace 7900 chain ring 53/39. The Di2 derailleur comes with a little red sticker that gets you to exactly the right gap (manual says 1-3 mm). Its just at the corner of the braze on and it interferes with the raised lip thats around the connector. The amount I had to remove was very small, and certainly not structural. I also sent this question to Cervelo directly, and although I cant post the reply, they did affirm that this question has arisen before, and my fix was typical of what has been done. It appears to affect all the model years, not just mine.

Only a small amount of  material needs to be removed and is not a problem. If you do not remove any material all it does it cut into the plasitc derailleur body a bit. It has no functional affect.

Compact cranks can be a problem though.  You can not get a Di2  to go low enough on a R series bike. The S series works fine with both compact and standard drive.

Sam:

Oh, oh! No way of making it fit with a compact crank? My 7800 derailleur worked with my Ultegra SL compact cranks, no problem. Used these cranks in Italy this year. I guess I'm going to have to focus on my hill climbing this winter!!

To be specific, are you saying that with the derailleur as far down as it will go, the gap to the chain rings is too large for the shifting to work? How much of that lip on the braze on can be ground off without compromising the structure?

Correct the der. will not sit low enough for a compact, If you use a compact you will decrease shifting performace/ increase chainrub, chain may rub on bottom of cage from sitting to high.  Better off not going compact. 

Ok. Thanks! Time to practice those big gears!

Picture of what I am talking about.

Looking at the picture for what is I guess a fairly standard fd hanger irespective of manufacturer, I would assume that this problem is not confined to Cervelo?

This should not be an issue with bikes with a clamp on dérailleur.

We did the Di2 install on my friends Look 595 last night, and the braze on, on that bike has the rivets behind the hanger and so there is no interference whatsoever. So I don't agree that this is a "standard design". Each manufacturer takes a slightly different approach, and as you can see from the picture, it doesn't take much to interfere. My understanding is that the S series cervelo models have a different braze on design that does not interfere.

One last comment. I had a short ride when I first installed my group on my R3 earlier this week, and I will say that the reviews are correct. The shifting is phenomenal, in particular the front. Combined with the ride quality and performance of the R3, I'm a very happy camper! Hopefully, if the weather holds out up here in Toronto for Sunday, I will get a longer ride in and come back with a more comprehensive review. My point is to advocate the Di2 on Cervelo bikes. I would encourage Cervelo (and perhaps Shimano) to come up with a solution to the retrofit issue for R models with compact cranks. I am convinced that when word gets out on how fantastic this group is on this bike, there will be lots more interest. Now of course, the popular notion is that the big deterrent is price. I will say that if you shop around online, and can sell your existing components you can upgrade for far less than what is quoted in the typical on line reviews. The install is relatively straight forward, and with both white and black (and grey) cable covers available, it looks really nice.

pm me if you want details or recommendations.

 <Correct the der. will not sit low enough for a compact, If you use a compact you will decrease shifting performace/ increase chainrub, chain may rub on bottom of cage from sitting to high.  Better off not going compact. >

State of the art FD without state of the art Crankset (Compact)?

Since there really is no reason NOT to go compact these days with the increased benefits of climbing steeper and steeper grades, BETTER high end, with newer cassettes, etc., it seems to me that this is a major drawback of the Di2.

By looking at it, a little redesign of either the hanger or the FD electrical attachment, is definitely in order. I'm surprised Shimano didn't thoroughly look at the limitations here, or maybe it's Cervélo's front hanger placement error, and not Shimano's design, but if they want to sell groupos, they should fit.

Still, it seems a simple Front hangar retrofit may be appropriate.

Aloha,

Jeff